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Osteology and relationships of Thaiichthys nov. gen.: A Ginglymodi from the Late Jurassic - Early Cretaceous of Thailand
Abstract
The osteology of Thaiichthys buddhabutrensis, nov. gen., from the Late Jurassic – Early Cretaceous of Thailand is described on the basis of a collection of well-preserved specimens. The mode of preservation of the material allows describing the external anatomy, as well as some elements of the internal anatomy (braincase, elements of the vertebral column). Most of the cranial and postcranial skeleton shows a rather conservative anatomy for ‘semionotiformes’, but the jaw apparatus displays specializations. Variations observed in the ossification pattern of the skull roof and of the cheek, in the morphology of the median dorsal scales and in fin rays’ count indicate that caution should be applied when these characters are used in diagnoses and in phylogenetic analyses. A phylogenetic analysis including a set of gars, of ‘semionotiformes’, of Macrosemiiformes and of Halecomorphi shows the following features: (1) the monophyly of Holostei; (2) sister-pair relationships between Tlayuamichin ⁄ Semiolepis, Isanichthys ⁄ ’Lepidotes’ latifrons and Araripelepidotes ⁄ Pliodetes; (3) the latter pair, together with Thaiichthys and possibly ‘Lepidotes’ mantelli, are resolved as stem Lepisosteiformes; and (4) the ‘semionotiformes’ (a group gathering species of Semionotus and Lepidotes) do not form a clade.
Supplementary resources (2)
... This clade flourished throughout almost the entire Mesozoic with a higher morphological and taxonomic diversity than their living descendants. Fossil ginglymodians were widely distributed from both freshwater and marine deposits in almost all continents except Australia and Antarctica, including Semionotiformes and Lepisosteiformes (Schaeffer and Dunkle 1950;Bartram 1977;Schultze and Möller 1986;Thies 1989, 1996, Olsen and McCune 1991, Wenz 1999, Bürgin 2004, Cavin and Suteethorn 2006, López-Arbarello et al. 2011, López-Arbarello 2012, Schröder et al. 2012, Cavin et al. 2013, Gibson 2013, Deesri et al. 2014, Brito et al. 2017. In recent years, a new order of ginglymodians, namely Kyphosichthyiformes (including Kyphosichthyidae and Lashanichthyidae), has been recognized from the Middle Triassic of South-West China, which represents the oldest record of this clade (Xu and Wu 2012, Sun and Ni 2018. ...
... The dermosphenotic is sub-triangular, tapering anteriorly (Figs 2C, 4C). The sphenotic [=autosphenotic of Rayner (1948)], not fused with the dermosphenotic, has a small exposed portion on the skull roof (Fig. 2C); this condition is also present in many other holosteans (Olsen and McCune 1991, Grande and Bemis 1998, Grande 2010, Cavin et al. 2013. ...
... In comparison, Ticinolepis and most lepisosteiforms have a mosaic of seven or more suborbitals, and their quadrates and metapterygoids are laterally covered by the suborbital or infraorbital bones (Grande 2010, López-Arbarello et al. 2016. Kyphosichthyids, Thaiichthysi, Dentilepisosteus, and Araripelepidotes, have relatively fewer (two or three) suborbitals with the quadrate laterally covered by infraorbital bones (Maisey 1991, Thies 1996, Grande 2010, Xu and Wu 2012, Cavin et al. 2013, and lashanichthyids and Isanichthys lertboosi have three to six suborbitals with the ventral suborbital laterally covering the quadrate (Deesri 2014. Additionally, only a single suborbital is present in some semionotiforms (Semionotus elegans, Lophionotus, and Semiolepis), and the suborbital is totally lost in macrosemiids; a laterally exposed quadrate was independently evolved in these semionotiforms (Bartram 1977, Olsen and McCune 1991, Gibson 2013, López-Arbarello et al. 2019. ...
Ginglymodians (e.g. gars) are a group of holostean fishes with a rich fossil history in the Mesozoic. The resolution of interrelationships among extinct ginglymodians is central to the problem of understanding the origin of this clade. Here, a new fossil ginglymodian, Diandongichthys ocellatus gen. et sp. nov., is described based on 13 well-preserved specimens from the Early-Middle Triassic (Anisian) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents one of the oldest and smallest ginglymodians hitherto known from the Middle Triassic, with a maximum standard length of 41 mm. Diandongichthys, although displaying several synapomorphies of ginglymodians, retains some primitive states with respect to other early ginglymodians (e.g. a short snout without anterior infraorbitals, a maxilla ending below the orbit, and a median gular); consequently, it is nested at the base of the Ginglymodi in this phylogenetic study. Besides body shape, some autapomorphies on the cranial bones and caudal fin easily distinguish Diandongichthys from other members of this clade. The discovery provides new insights into the origin and early diversification of ginglymodian fishes.
... Numerous studies have been dedicated to the morphology of living gars, Amia and their direct fossil relatives (see [5,23] and literature cited therein) and, although the morphology of many fossil holosteans is still poorly known, numerous fossil holostean and teleost taxa, several of them representing extinct lineages, have been studied in detail and included in cladistic analyses during the last decades (e.g. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]). These studies represent important steps towards a Total Evidence analysis of the Neopterygii, in which missing information should not be problematic because the fossil taxa will be properly anchored in the tree thanks to the available molecular and morphological information on the living representatives [20,21]. ...
... 23, [26]: ch. 7, [72]: ch. 16, [29]: ch. 10, [27]: ch. 34, [33]: ch. ...
... The fusion between dermosphenotic and sphenotic is also equated with the dermal component of the sphenotic and incorrectly scoring the presence of this latter feature in † Obaichthys and † Dentilepisosteus in Arratia ( [29]: ch. 10), Cavin et al. ( [27]: ch. 34), Bermúdez-Rochas & Poyato-Ariza ( [96]: ch. ...
The phylogenetic relationships of the recently described genus†Ticinolepis from the Middle Triassic of the Monte San Giorgio are explored through cladistic analyses of the so far largest morphological dataset for fossil actinopterygians, including representatives of the crown-neopterygian clades Halecomorphi, Ginglymodi and Teleostei, and merging the characters from previously published systematic studies together with newly proposed characters.†Ticinolepis is retrieved as the most basal Ginglymodi and our results support the monophyly of Teleostei and Holostei, as well as Halecomorphi and Ginglymodi within the latter clade. The patterns of relationships within these clades mostly agree with those of previous studies, although a few important differences require future research. According to our results, ionoscopiforms are not monophyletic, caturids are not amiiforms and leptolepids and luisiellids form a monophyletic clade. Our phylogenetic hypothesis confirms the rapid radiation of the holostean clades Halecomorphi and Ginglymodi during the Early and Middle Triassic and the radiation of pholidophoriform teleosts during the Late Triassic. Crown-group Halecomorphi have an enormous ghost lineage throughout half of the Mesozoic, but ginglymodians and teleosts show a second radiation during the Early Jurassic. The crown-groups of Halecomorphi, Ginglymodi and Teleostei originated within parallel events of radiation during the Late Jurassic.
... Another hypothesis that places Ginglymodi as the sister group of Teleostei has also been proposed (Olsen, 1984), but it is very weekly supported and has rarely been accepted. In the last decade, however, the Halecostomi concept has been challenged; recent analyses based on both morphological and molecular data consistently support sister-group relationships between Halecomorphi and Ginglymodi and, consequently, the Holostei concept was resurrected (Inoue et al., 2003;Hurley et al., 2007;Grande, 2010;Nakatani et al., 2011;Near et al., 2012;Broughton et al., 2013;Cavin, Deesri early fossil record. The placement of the early Permian (Artinskian) Brachydegma in the Halecomorphi (Hurley et al., 2007) was rejected in subsequent studies (Near et al., 2012;Xu et al., 2014;Argyriou, 2017). ...
... The sphenotic (= autosphenotic of Rayner, 1948), not fused with the dermosphenotic, has a small portion participating in the skull roof, as in many other holosteans (Olsen & McCune, 1991;Grande & Bemis, 1998;Grande, 2010;Cavin et al., 2013). This exposed portion is smooth on the surface. ...
... The additional 46 characters were derived from other sources (e.g. Gardiner & Schaeffer, 1989;Gardiner et al., 1996;Coates, 1999;Arratia, 1999Arratia, , 2013Cavin & Suteethorn, 2006;Alvarado-Ortega & Espinosa-Arrubarrena, 2008;Cavin, 2010;Grande, 2010;Xu & Gao, 2011;López-Arbarello, 2012;Brito & Alvardo-Ortega, 2013, Cavin et al., 2013Deesri et al., 2014;Xu, Gao & Coates, 2015;Xu & Zhao, 2016;Xu & Ma, 2016). All characters were unordered and equally weighted. ...
The previously alleged 'semionotid' fish Asialepidotus shingyiensis from the Middle Triassic (Ladinian) marine deposits of Guizhou and Yunnan, China has recently been identified as a halecomorph, but its phylogenetic relationships with other halecomorphs remain controversial. This taxon was successively placed in different halecomorph orders: Amiiformes, Parasemionotiformes and 'Panxianichthyiformes'. Here, a detailed redescription of Asialepidotus is presented based upon a comparative study of the original material with 50 new specimens. Newly recognized anatomical information includes a V-shaped rostral, paired vomers, a toothed parasphenoid, a dermosphenotic with a canal-bearing innerorbital flange, a splint-like quadratojugal, a branch of the infraorbital sensory canal in the maxilla, and many elements in the hyoid and branchial apparatuses and the lower jaw. Results of a cladistic analysis incorporating these new data indicate that the 'Panxianichthyiformes' is a poorly defined, paraphylectic grade; Asialepidotus is not sister to Panxianichthys as previously suggested; instead, it is more derived than Panxianichthys and consists of the sister taxon of the clade Robustichthys plus Jurassic-Cretaceous ionoscopiforms. This phylogen-etic reassessment of Asialepidotus extends the stratigraphic range of the Ionoscopiformes in China by ~4 Myr and supports the hypothesis that the early ionoscopiform diversification was already established by the Middle Triassic.
... Several species of Semionotus and Lepidotes, as well as closely related genera, are known by well preserved material. Their anatomical descriptions, associated with cladistic analyses, have led to a better understanding of the group (Woodward, 1916;Saint-Seine, 1949;Patterson, 1975;Thies, 1989;Maisey, 1991;Olsen and McCune, 1991;Tintori, 1996;Arratia and Schultze, 1999;Wenz, 1999Wenz, , 2003Su, 2003;Gallo, 2005;Cavin and Suteethorn, 2006;L opez-Arbarello and Codorni u, 2007;Tintori and Lombardo, 2007;Lombardo and Tintori, 2008;Cavin, 2010;Grande, 2010;Forey et al., 2011;L opez-Arbarello and Alvarado-Ortega, 2011;Cavin et al., 2013;Gibson, 2013aGibson, , 2013bDeesri et al., 2014). In particular, L opez-Arbarello (2012) provided an important review of the group and proposed a new phylogenetic framework, which led to a new taxonomic ordering. ...
... In particular, L opez-Arbarello (2012) provided an important review of the group and proposed a new phylogenetic framework, which led to a new taxonomic ordering. Some traits of L opez-Arbarello's phylogeny are shared with other recent studies (Cavin, 2010;Cavin et al., 2013;Gibson, 2013b;Deesri et al., 2014), such as the gar lineage rooted within a group of Jurassic and Cretaceous 'semionotiforms'; Araripelepidotes and Pliodetes, from the Early Cretaceous of western Gondwana, closely related to each other and placed as the sister group of gars (represented by Lepisosteidae C Obaichthyidae); and Scheenstia, Lepidotes, and Isanichthys resolved as basal Lepisosteiformes in two of these studies (Gibbson, 2013b;Deesri et al., 2014). Both Gibson's (2013b) and L opez-Arbarello's (2012) phylogenies recovered a clade to which the name Semionotiformes was attached, including the Callipurbeckidae, the Macrosemiidae, and some other genera, whereas in other studies most of these taxa are resolved as stem Lepisosteiformes (Cavin et al., 2013;Deesri et al., 2014) and the Macrosemiiformes constitute a basal clade of Ginglymodi. ...
... Some traits of L opez-Arbarello's phylogeny are shared with other recent studies (Cavin, 2010;Cavin et al., 2013;Gibson, 2013b;Deesri et al., 2014), such as the gar lineage rooted within a group of Jurassic and Cretaceous 'semionotiforms'; Araripelepidotes and Pliodetes, from the Early Cretaceous of western Gondwana, closely related to each other and placed as the sister group of gars (represented by Lepisosteidae C Obaichthyidae); and Scheenstia, Lepidotes, and Isanichthys resolved as basal Lepisosteiformes in two of these studies (Gibbson, 2013b;Deesri et al., 2014). Both Gibson's (2013b) and L opez-Arbarello's (2012) phylogenies recovered a clade to which the name Semionotiformes was attached, including the Callipurbeckidae, the Macrosemiidae, and some other genera, whereas in other studies most of these taxa are resolved as stem Lepisosteiformes (Cavin et al., 2013;Deesri et al., 2014) and the Macrosemiiformes constitute a basal clade of Ginglymodi. In Cavin (2010), most of the non-lepisosteiform and non-macrosemiiform taxa form a clade, but its composition differs from the Semionotiformes of L opez-Arbarello (2012). ...
A new ginglymodian fish, Khoratichthys gibbus, gen. et sp. nov., is described based on the impression of a single articulated fish preserved on a sandstone slab from the Late Jurassic–Early Cretaceous Phu Kradung Formation, northeastern Thailand. Khoratichthys gibbus is characterized by a distinct humpbacked body with elongate posterior spines on the dorsal ridge scales; the cheek is completely covered by bone; it has few infraorbitals, the elongate anterior-most one shows a tiny contact with the orbit, and six suborbitals arranged in one row; the opercule is rectancular in shape; the preopercule is narrow and regularly curved; and the interopercule large. A cladistic analysis including the type species of 25 ginglymodian genera indicates that Khoratichthys is the basal-most Lepisosteiformes, in an unresolved position with Neosemionotus and Lophionotus. This taxon provides a new evidence of the high diversity of ginglymodian fishes in the Phu Kradung Formation. A high taxic diversity of ginglymodians in Middle Jurassic–Early Cretaceous of southern Asian (excluding India) freshwater environments is observed, indicating that this clade occupied a major position in freshwater fish assemblages.
http://zoobank.org/urn:lsid:zoobank.org:pub:AE3056BF-0C4A-421F-B517-3A4BC777A3E1
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Citation for this article: Deesri, U., P. Jintasakul, and L. Cavin. 2016. A new Ginglymodi (Actinopterygii, Holostei) from the Late Jurassic–Early Cretaceous of Thailand, with comments on the early diversification of Lepisosteiformes in Southeast Asia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1225747.
... During the 20th century, studies on Mesozoic ginglymodians were hampered by difficulties in the definition of the genera Semionotus Agassiz (1832) and Lepidotes Agassiz (1832), but entering the new century and especially after the revision of these two important genera (López-Arbarello 2008, 2012, significant progress has been made on the systematics of this group (Cavin and Brito 2001;Brito and Gallo 2003;Wenz 2003;González-Rodríguez and Reynoso 2004;Gallo 2005;Cavin and Suteethorn 2006;López-Arbarello and Codorniú 2007;Tintori and Lombardo 2007;Lombardo and Tintori 2008;Cavin 2010;Grande 2010;Forey et al. 2011;López-Arbarello and Alvarado-Ortega 2011;López-Arbarello 2012;Schröder et al. 2012;Xu and Wu 2012;Cavin et al. 2013;Gibson 2013a, b;Chen et al. 2014;Deesri et al. 2014;Bermúdez-Rochas and Poyato-Ariza 2015;Murray et al. 2015;Alvarado-Ortega et al. 2016). ...
... The two main lineages of Ginglymodi as proposed by López-Arbarello (2012) basically remain the same: Lepisosteiformes including the genera Lepidotes and Scheenstia, and Semionotiformes including semionotids, callipurbeckiids and macrosemiids among other taxa. Also in agreement with previous phylogenetic hypotheses, Isanichthys palustris and Thaiichthys buddhabutrensis are more closely related to lepisosteids than to other ginglymodians (Cavin 2010;Cavin et al. 2013;Bermúdez-Rochas and Poyato-Ariza 2015) and are here included in the clade Lepisosteoidei López-Arbarello (2012). However, our analysis differs in the relationships of Camerichthys lunae Bermúdez-Rochas and Poyato-Ariza (2015), from the Tithonian-Berriasian of Spain. ...
... Thaiichthys Cavin et al. (2013) (probably Early Cretaceous). Recently, Deesri et al. (2014) described a second Thai species of Isanichthys, I. lertboosi, and referred two other species to this genus: I. latifrons (Woodward 1893) from the Late Jurassic of England and I. luchowensis (Wang 1974) from the Early or Middle Jurassic of Sichuan, China. ...
Ginglymodian fishes are abundant and diverse in Upper Jurassic limestones of Germany, but rarer in coeval sequences in France. Only a single ginglymodian is so far known from the Tithonian at Canjuers. Our study of this excellently preserved specimen revealed that it represents a new taxon †Occitanichthys canjuersensis gen. et sp. nov., which is retrieved in a cladistic analysis as a member of the semionotiform family †Callipurbeckiidae. Additionally, two specimens among fishes from the Middle Purbeck Beds at Swanage referred to †Callipurbeckia minor were found to represent the new callipurbeckiid taxon. The new taxon inhabited the epicontinental seas that covered most of Europe connecting the Tethys with the North Atlantic during Jurassic and Cretaceous, and its minimum biochron ranges from the Early Tithonian to the Early Cretaceous. After incorporation of the new and recently described taxa and the re-evaluation and addition of morphological characters, our cladistic analysis recovered a somewhat different pattern of relationships compared with previous phylogenetic hypotheses for Ginglymodi. Mainly, in the new topology, a monophyletic †Lepidotidae includes the Jurassic genera †Lepidotes and †Scheenstia, and the Tithonian–Berriasian †Camerichthys from Spain, which has been classified in †Semionotiformes. Among semionotiforms, our results retrieved the family †Macrosemiidae as the sister group of †Semionotidae occupying a more distal position within the clade †Semionotiformes than previously thought.
... Patterson (1973) 7 questioned this concept: he regarded the Holostei as a non-monophyletic group and considered the Semionotidae as Halecostomi, i.e. as closer to teleosts than to gars (Lepisosteidae). Alternatively, Olsen and McCune (1991) 8 12 ), and this confi guration was subsequently also found in morphological studies, which included fossil taxa 13,14 . ...
... In his review of the Lepisosteiformes Grande (2010) 13 proposed a classifi cation, in which the Holostei include the Halecomorphi and a clade called Ginglymodi, which gathers gars together with several extinct taxa. Most recent studies have found the monophyly of Ginglymodi containing the Lepisosteiformes, 'macrosemiiformes' and 'semionotiformes', but there is still no consensus about the respective composition and relationships of the latter two groups (compared for instance López-Arbarello 2012 2 with Cavin et al. 2013 14 and Deesri et al. 2014 15 ). ...
... So far this site has yielded only bony fi shes, and this discovery triggered specifi c researches on this group of vertebrates. Most of the specimens belong to a ginglymodian fi sh, Thaiich-thys buddhabutrensis (Cavin, Suteethorn, Khansubha, Buffetaut & Tong, 2003) 27 , which was described in detail only recently 14 . A taphonomical and morphometric study of the T. buddhabutrensis assemblage was published by Deesri et al. 28 in 2009. ...
Isolated ganoid fi sh scales are not uncommon in Mesozoic deposits of Thailand. Traditionally referred to ‘semionotiform’ or Lepidotes-like fi shes, they were not assigned to well-defi ned taxa and are of little use for palaeontological reconstructions. During the last fi fteen years, however, the discovery of well-preserved articulated fi sh specimens, with ganoid squamations, allowed us to properly defi ne new taxa, to search for phylogenetic relationships and to address the place of these fi shes in palaeoenvironments. So far two genera and three species of ginglymodians have been named on the basis on material from the Phu Kradung Formation, but at least nine different taxa have been recognized ranging from the Late Triassic to the Aptian. Phylogenetic analyses of Thaiichthys and Isanichthys indicate that they belong, or are closely related, to the Lepisosteiformes. The palaeogeographical distribution of the four known Isanichthys species is restricted to the northern margin of the Tethys during the Middle Jurassic to the basal Cretaceous. The palaeobiogeographical signal of Thaiichthys is more ambiguous, its closest relatives having been found in the early Late Cretaceous of western Gondwana (South America and Africa).
... Ginglymodi is a clade of ray-finned fishes comprising the Lepisosteiformes (gars and extinct relatives), and the extinct "Semionotiformes" and Macrosemiiformes (Grande 2010). Lepisosteiformes and Macrosemiiformes are well characterized by osteological characters, but the "Semionotiformes" are still poorly defined (Cavin 2010;Cavin et al. 2013). In these studies, the "Semionotiformes" are positioned as stem taxa to the Lepisosteiformes, but show poorly resolved intrarelationships. ...
... Importantly, a clade called Semionotiformes is resolved: it comprises the Semionotidae, the Callipurbeckiidae, and the Macrosemiidae. The set of characters used in López-Arbarello's analysis differs from the set of characters used in analyses of Cavin (2010), Cavin et al. (2013) and in the present study. We discuss and compare our results with those of López-Arbarello (2012). ...
... The sphenotic is also visible on both sides of KS36-2 (holotype) and KS36-3, in which the ossification develops a lateral blunt process that is visible on the cheek along the ventral margin of the dermosphenotic (Figs. 3, 4). A small dermal component of the sphenotic process is also visible in specimens of other ginglymodians (see Cavin et al. 2013 for a review). In gars the sphenotic is visible laterally and separated from the dermosphenotic (Grande 2010). ...
A new ginglymodian fish, Isanichthys lertboosi, is described from the Phu Kradung Formation, north-eastern Thailand, a freshwater deposit of probable Late Jurassic age. The species is represented by four specimens, from the Phu Noi locality, associated with a rich fauna of sharks, turtles, crocodiles, and theropod and sauropod dinosaurs. One specimen is an isolated braincase, which provides characters rarely observed in extinct ginglymodians. The species is referred to the genus Isanichthys, a taxon originally described on the basis of a single specimen from the Phu Nam Jun locality, a slightly younger site approximately 75 km from Phu Noi. Isanichthys is mainly distinguished by frontals slightly narrower anteriorly than posteriorly, two anterior infraorbitals not in contact with the orbit, reduced preorbital region, and a small orbit and a cheek region completely covered by bones. The new species is characterized, among other characters, by a dermal component of the sphenotic visible on the cheek, one pair of extrascapulars plus a small median one, the presence of few suborbitals (ca. 4 or 6) arranged in one row, and a median dorsal row of scales with spine. Comparisons with other ginglymodian taxa and a cladistic analysis indicates that Isanichthys (Lepidotes) latifrons from the Late Jurassic of England, as well as probably Isanichthys (Lepidotes) luchowensis from the Early or Middle Jurassic of Sichuan, China, form a clade with both Thai species of Isanichthys. The new species provides evidence of the high diversity of ginglymodian fishes in the Phu Kradung Formation and suggests a new hypothesis of phylogenetic relationships among extinct ginglymodians.
... For two decades, several studies have revised species traditionally referred to Lepidotes and species related to the other wastebasket genus Semionotus, as well as other 'semionotiform' taxa mostly from Europe (Wenz 2003;L opez-Arbarello 2008L opez-Arbarello , 2012; L opez-Arbarello & Sferco 2011; L opez-Arbarello & Wencker 2016; L opez-Arbarello et al. 2019), but also form North America (Gibson 2013) and South America (Wenz & Brito 1996;Gallo & Brito Paiva & Gallo 2018). In parallel, the discovery of new material has allowed the recognition of new taxa related to Lepidotes and Semionotus, in particular from the Triassic of Europe (Tintori & Lombardo 2007) and China Wen et al. 2011;Sun & Ni 2017;Xu et al. 2018), from the Early Cretaceous of Mexico (L opez-Arbarello & Alvarado-Ortega 2011), from the Late Jurassic-Early Cretaceous of Southeast Asia (Cavin & Suteethorn 2006;Cavin et al. 2013Cavin et al. , 2019Deesri et al. 2014Deesri et al. , 2016, and eventually from the Cretaceous of Africa (Wenz 1999;Forey et al. 2011). ...
... Wedged between the two posterior infraorbitals along the orbital margin is a small, rounded supplementary infraorbital. A similar pattern is observed in some specimens of Thaiichthys buddhabutrensis (Cavin et al. 2013). Two other infraorbitals located along the ventral margin of the orbit are visible laterally as pentagonal ossifications bearing some traces of ornamentation. ...
Lepidotes bernissartensis is a species of holostean ray-finned fish from the Barremian-Aptian of Bernissart, Belgium, described by Traquair in 1911. We provide here a revision of its anatomy, which led us to include this species in the genus Scheenstia, and to consider L. brevifulcratus and L. arcuatus, both from the same site, synonymous with S. bernissartensis. We performed two cladistic analyses in order to assess the phylogenetic position of S. bernissartensis and to do an updated appraisal of the evolutionary history of the ginglymodians. Scheenstia is included in the Lepidotidae, and placed in a pectinated position between the basal genus Lepidotes and the more derived members of the family (other species of Scheenstia, Isanichthys and Camerichthys). The nodes within the lepidotids are weakly supported. Although S. bernissartensis is not directly related to S. mantelli from the Wealden of Europe, the two species have similar palaeoenvironments and stratigraphical ranges. Taken as a whole, the ginglymodians experienced several episodes of diversification that are spatially and temporally restricted. The oldest episode involved basal ginglymodians and occurred in the Middle Triassic, in marine environments along the northern margin of the Tethys. A second episode affected the Semionotidae and occurred in freshwater environments of North America and Europe in the Late Triassic and Early Jurassic. The remaining Semionotiformes, Macrosemiidae and Callipurbeckidae, ranged from the Triassic to the Early Cretaceous and were mostly marine. Among the Lepisosteiformes, two clades, the Lepidotidae and the Lepisosteoidi, show episodes of diversification, first in marine and then in freshwater environments.
... Many Lepidotes species were worldwide recorded during most parts of the twentieth century, even in the Brazilian sedimentary basins (Gallo and Brito, 2004;Gallo, 2005;Paiva et al., 2013Paiva et al., , 2014Cavin et al., 2013). Among the Brazilian "Lepidotes", "L." piauhyensis (Roxo and Löfgren, 1936) is the best described one, especially because of the relatively great amount of well-preserved and articulated specimens (Paiva, 2017). ...
... Additionally, all the others "Lepidotes" species out of the estimated range need a review, as anteriorly proposed in Cavin (2010), which was tested in some studies (e.g. Cavin et al., 2013;Deesri et al., 2014;Cavin et al., 2018). In addition, López-Arbarello and Wencker (2016) and López-Arbarello and Sferco (2018) improved their studies and affirmed that true Lepidotes remains in Lepisosteiformes, included in Lepidotidae, a family previously proposed in Owen (1860). ...
... Most of the bones of the cheeks shifted slightly before fossilization, and their precise original arrangement is difficult to reconstruct (keeping in mind that the arrangement may vary between the two sides of a single specimen; e.g. see Cavin et al. 2013). The probable positions of the small orbits are shown in Figure 2B and C. The indisputable feature of the cheek pattern is the presence anterior to the orbit of a very deep bone, approximately 2.5 times deeper than wide, preceded anteriorly by a large approximately trapezoidal bone, 2 times deeper than wide, and more anteriorly by a third trapezoidal bone ( Fig. 2). ...
... Another difference is the position of Neosemionotus, from the Early Cretaceous of Argentina, which had a variable position in previous studies. It has been located in a basal polytomy of the Ginglymodi (L opez Arbarello 2012;Gibson 2013;Berm udez-Rochas & Poyato-Ariza 2015), as the most basal lepisosteiform ( Cavin 2010;Deesri et al. 2016;Sun & Ni 2017) or nested among a series of genera in pectinate arrangement ( Cavin et al. 2013;Deesri et al. 2014). In the present analysis, Neosemionotus is resolved as the most basal semionotiform, followed by Lepidhoyas microrhis, an interesting Early Cretaceous species from Spain rarely included in phylogenetic analysis. ...
A new genus and new species of ginglymodian is described from the Aptian Grès supérieurs Formation of the Savannakhet Basin, Laos (Lao People's Democratic Republic), found at the Ban Lamthouay locality. The fish is known from a single isolated head, which shows enough diagnostic characters to characterize a new taxon. It represents the first named actinopterygian fish from the Mesozoic of Laos. Among the derived characters are a very short and deep head, a series of very deep anterior infraorbitals, and a mosaic arrangement of the suborbitals. Recognition of this new form led us to identify isolated bones previously found in the Thai Khok Kruat Formation in Thailand, a lateral equivalent of the Grès supérieurs Formation. Two localities, Ban Saphan Hin and Khok Pha Suam, have yielded remains, in particular bones of the skull roof and of the circumorbital series as well as a partial postcranial body, assignable, with caution, to the new genus. When included in a cladistic analysis, the new taxon is placed at the base of the lepisosteoid lineage, together with Isanichthys known from an older formation in Thailand. The phylogenetic pattern obtained differs in some details from previous analyses and points out the pivotal role that some taxa play in the reconstruction of the phylogenies of ginglymodians. This new taxon enriches the diverse Late Jurassic–Early Cretaceous ginglymodian assemblage in South-east Asia, which surprisingly shows no evidence of teleosts.
http://zoobank.org/urn:lsid:zoobank.org:pub:70564BE0-939C-4217-9D82-9E51AA298A8C
... Many Lepidotes species were worldwide recorded during most parts of the twentieth century, even in the Brazilian sedimentary basins (Gallo and Brito, 2004;Gallo, 2005;Paiva et al., 2013Paiva et al., , 2014Cavin et al., 2013). Among the Brazilian "Lepidotes", "L." piauhyensis (Roxo and Löfgren, 1936) is the best described one, especially because of the relatively great amount of well-preserved and articulated specimens (Paiva, 2017). ...
... Additionally, all the others "Lepidotes" species out of the estimated range need a review, as anteriorly proposed in Cavin (2010), which was tested in some studies (e.g. Cavin et al., 2013;Deesri et al., 2014;Cavin et al., 2018). In addition, López-Arbarello and Wencker (2016) and López-Arbarello and Sferco (2018) improved their studies and affirmed that true Lepidotes remains in Lepisosteiformes, included in Lepidotidae, a family previously proposed in Owen (1860). ...
Ontogenia é a soma das mudanças sofridas pelos organismos ao longo do tempo
biológico. Entretanto, o registro fossilífero é incompleto e a informação
ontogenética em fósseis, limitada. Porém, mesmo com poucos exemplares, é
possível recuperar importantes informações sobre estágios ontogenéticos em
fósseis. Na última revisão de "Lepidotes" piauhyensis, foram encontradas
evidências de três estágios ontogenéticos, separados em quatro grupos distintos:
juvenil 1, juvenil 2, subadulto e adulto.
... Abundant fossils of actinopterygians were reported from the Mesozoic continental red beds of the Khorat Group in Northeastern Thailand (Buffetaut and Suteethorn, 1998). A total of 6 species of actinopterygians have been named, including mostly ginglymodians such as Isanichthys palustris (Cavin & Suteethorn, 2006), I. lertboosri (Deesri et al., 2014), Thaiichthys buddhabutrensis (Cavin et al., 2013), Khoratichthys gibbus (Deesri et al., 2016), Lanxangichthys alticepha-lus (Cavin et al., 2019), and a single sinamid, Siamamia naga (Cavin et al., 2007). Another Palaeonisciformes, cf. ...
The actinopterygian fossil was found from the Permian carbonate succession of Tak Fa Formation, Saraburi Group, in Bueng Sam Phan District, Phetchabun Province, central northeast Thailand. The partially preserved body part with ganoid scales is identified as belonging to a ray-finned fish (subclass Actinopterygii). The squamation is composed of smooth-surfaced articulated scales with a hard-diamond shape. The posterior part of the specimen showed some translucent ganoine covering mineralized bone layers. The microstructure of squamation is characterized by the presence of 3-6 ridges running parallel to the antero-ventral margin of scales on the bone layer. This suggests that the Paleozoic actinopterygian specimens from Phetchabun likely belong to Palaeoniscum sp. The age of the fauna is assigned to the Early to Middle Permian based on the presence of microfossils and invertebrates recovered from nearby areas. The paleoenvironments of the area corresponded to lagoons or subtidal zones with a low-energy depositional condition according to lithological, stratigraphical, and petrographic examinations of limestones interbedded with shales. This study represents the first record of palaeoniscids from Southeast Asia during the Early to Middle Permian and supported the idea that the Indochina terrane was a part of epeiric seas at that time.
... During the Mesozoic, ginglymodians made several freshwater incursions and were exclusively restricted to freshwaters by the Late Cretaceous (Cavin, 2010). After their migration into freshwaters, new trophic adaptations appeared in ginglymodians allowing them to occupy new ecological niches such as suction feeding on small invertebrates (Thies, 1996) and herbivory/detritivory (Cavin et al., 2013). From the late Early Cretaceous onwards, a new and significant family of ginglymodians, the gars (Lepisosteidae) appeared, survived the K/Pg extinction event and are the only ginglymodians still living today. ...
Pycnodontiformes was a successful lineage of primarily marine fishes that broadly diversified during the Mesozoic. They possessed a wide variety of body shapes and were adapted to a broad range of food sources. Two other neopterygian clades possessing similar ecological adaptations in both body morphology (†Dapediiformes) and dentition (Ginglymodi) also occurred in Mesozoic seas. Although these groups occupied the same marine ecosystems, the role that competitive exclusion and niche partitioning played in their ability to survive alongside each other remains unknown. Using geometric morphometrics on both the lower jaw (as constraint for feeding adaptation) and body shape (as constraint for habitat adaptation), we show that while dapediiforms and ginglymodians occupy similar lower jaw morphospace, pycnodon-tiforms are completely separate. Separation also occurs between the clades in body shape so that competition reduction between pycnodontiforms and the other two clades would have resulted in niche partitioning. Competition within pycnodontiforms seemingly was reduced further by evolving different feeding strategies as shown by disparate jaw shapes that also indicate high levels of plasticity. Acanthomorpha was a teleostean clade that evolved later in the Mesozoic and which has been regarded as implicated in driving the pycnodontiforms to extinction. Although they share similar body shapes, no coeval acanthomorphs had similar jaw shapes or dentitions for dealing with hard prey like pycnodontiforms do and so their success being a factor in pyc-nodontiform extinction is unlikely. Sea surface temperature and eustatic variations also had no impact on pycnodontiform diversity patterns according to our results. Conversely, the occurrence and number of available reefs and hardgrounds as habitats through time seems to be the main factor in pycnodontiform success. Decline in such habitats during the Late Cretaceous and Palaeogene might have had deleterious consequences for pycnodontiform diversity. Acanthomorphs occupied the niches of pycnodontiforms during the terminal phase of their existence.
... The Adamantina Formation represents freshwater deposits, which is consistent with what is known about the ecological lifestyle of most lepisosteoids which are found predominantly in freshwater deposits, especially the lepisosteids (see in Table 3). (1818); 2) Agassiz (1832); 3) Agassiz (1836); 4) Jaekel (1929); 5) L opez-Arbarello and Sferco (2011); 6) Agassiz (1833); 7) Agassiz (1837); 8) Brito et al. (2017); 9) Wagner (1863); 10) Branco (1885); 11) Cavin and Suteethorn (2006); 12) Cavin et al. (2013); 13) Brito and Richter (2015); 14) Cavin et al., (2020); 15) Wenz and Brito (1992); 16) Wenz and Brito (1996); 17) Silva Santos (1994); 18) Brito et al. (2016); 19) Wenz (1999); 20) Casier (1961); 21) Ciffeli et al. (1999); 22) Veiga et al. (2019); 23) Grande (2010); 24) Cavin and Brito (2001); 25) Werner (1993); 26) Cavin et al. (2015); 27) Torices et al. (2012); 28) Vullo and N eraudeau. (2008); 29) Friedman et al. (2003); 30) Silva Santos (1984); 31) Martinelli and Teixeira (2015); 32) Gayet and Meunier (1998) Wiley and Stewart (1977); 37) Case and Schwimmer (1988); 38) Becker et al. (2009); 39) Willey (1976); 40) Rodriguez de la Rosa and Cevallos-Ferriz (1998); 41) Rowe et al. (1992); 42) Ortega et al., 2015;43) Perez-Garcia et al. (2016); 44) Cavin et al. (1996); 45) Buffetaut et al. (1996); 46) Gottfried and Krause (1998); 47) Kumar et al. (2005); 48) Alves et al. (2016); 49) Cione (1987); 50) Previtera and Gonz alez-Riga (2008); 51) Martinelli and Forasiepi (2004); 52) Kear et al. (2009); 53) Astibia et al. (1990); 54) Tong et al. (1993); 55) Pereda-Suberbiola et al. (2015); 56) Sig e et al. (1997); 57) Gayet and Meunier (1998); 58) ; 59) Rana (1990); 60) Blanco and Bolet (2014); 61) Le Loeuff et al. (1992); 62) Laurent et al. (2002); 63) Marmi et al. (2016); 64) Gricorescu et al. (1999); 65) Codrea et al. (2010); 66) Csiki et al. (2008). ...
The superfamily Lepisosteoidea, popularly known as gars, is the only group of extant ginglymodian fishes that has its history traced back to the Mesozoic. The extant diversity of the superfamily comprises one family, two genera and seven species. The oldest fossils of Lepisosteoidea are known from Upper Jurassic deposits in Mexico. From the Early Cretaceous onwards, lepisosteoids diversified into two major lineages: Lepisosteidae, that encompasses modern gars, and the currently extinct family Obaichthyidae. In this paper, we report new lepisosteid remains, attributed for the first time to Atractosteus sp., from the Turonian–Santonian Adamantina Formation, Bauru Group, Brazil. The anatomical description and assessment of taxonomically relevant characters was employed with the support of data from Scanning Electron Microscopy (SEM) and histological analyses. The presence of plicidentine tooth structure and lepidosteoid-type scales, without an intercalated dentine layer, allows the assignment of these remains to Lepisosteidae. The size and density of the microornamentations of the scales of the new remains were also compared to measurements of other lepisosteoids, which allowed their assignment to Atractosteus. These new fossils allow biogeographical inferences regarding Lepisosteoidea origins and their distributions along the Mesozoic. The origin of Lepisosteoidea may have occurred in the Sinemurian-Toarcian of Tethys, whereas the origin of Lepisosteidae can be explained by a cladogenetic event associated with the break-up of the Pangaea supercontinent. Both vicariance or dispersal events could explain the presence of lepisosteids, originally from Africa or North America, in South American.
... Hence, the Malaysian 'Lepidotes' sp. is of little stratigraphic value. On the other hand, Ginglymodi is a broad monophyletic group, ranging in age from the Triassic up to the Recent (Lopez-Arbarello, 2012; Cavin et al., 2013). The Malaysian Ginglymodi indet. ...
Cretaceous fish fossils are reported from Malaysia for the first time. They were found with dinosaur and turtle remains in nonmarine sediments in the interior of Pahang State, Peninsular Malaysia. This fish assemblage consists mostly of isolated teeth, with minor amounts of noncranial remains, including vertebral centra, scales, coprolites, and hybodont fin spines. Over 100 fish teeth were examined. Nine taxa were confirmed from this fish assemblage: six (identified and unidentified) species of hybodont sharks, Heteroptychodus kokutensis, Isanodus paladeji, Lonchidion aff. khoratensis, Mukdahanodus aff. trisivakulii, Egertonodus sp., and Hybodontidae indet., and three species of actinopterygians (ray-finned fishes): ‘Lepidotes’ sp., Halecomorphi indet., and Ginglymodi indet. This fish assemblage has strong affinities with Early Cretaceous (Barremian–early Aptian) faunas of Thailand, because the four hybodont species, H. kokutensis, I. paladeji, L. khoratensis, and M. trisivakulii, were previously known only from the Sao Khua Formation (Khorat Group) and equivalent strata of Ko Kut (Kut Island). Egertonodus has been confirmed in Asia for the first time. Overall, this fish assemblage shows a close linkage to Early Cretaceous (Barremian–early Aptian) faunas of Thailand. Based on faunal composition and biostratigraphic correlation, we suggest a Barremian–early Aptian age for this new fauna from Malaysia.
... Therefore, if these osteoglossomorphs and otocephalan clades were geographically restricted, it may be that the lack of freshwater sites sampled for fishes from comparable regions of the globe either side of the Jurassic/Cretaceous boundary contributes to their apparent absence in the Jurassic. Eastern Thailand offers an exception, where Late Jurassic and Berrasian freshwater deposits have been found (Cavin et al. 2013a;Deesri et al. 2014Deesri et al. , 2016. However, these sites are dominated by lepisosteiforms, with no evidence of crown teleosts, despite systematic excavations and sieving. ...
Comprising Holostei and Teleostei, the ~32,000 species of neopterygian fishes are anatomically disparate and represent the dominant group of aquatic vertebrates today. However, the pattern by which teleosts rose to represent almost all of this diversity, while their holostean sister-group dwindled to eight extant species and two broad morphologies, is poorly constrained. A geometric morphometric approach was taken to generate a morphospace from more than 400 fossil taxa, representing almost all articulated neopterygian taxa known from the first 150 million years—roughly 60%—of their history (Triassic‒Early Cretaceous). Patterns of morphospace occupancy and disparity are examined to: (1) assess evidence for a phenotypically “dominant” holostean phase; (2) evaluate whether expansions in teleost phenotypic variety are predominantly abrupt or gradual, including assessment of whether early apomorphy-defined teleosts are as morphologically conservative as typically assumed; and (3) compare diversification in crown and stem teleosts. The systematic affinities of dapediiforms and pycnodontiforms, two extinct neopterygian clades of uncertain phylogenetic placement, significantly impact patterns of morphological diversification. For instance, alternative placements dictate whether or not holosteans possessed statistically higher disparity than teleosts in the Late Triassic and Jurassic. Despite this ambiguity, all scenarios agree that holosteans do not exhibit a decline in disparity during the Early Triassic‒Early Cretaceous interval, but instead maintain their Toarcian‒Callovian variety until the end of the Early Cretaceous without substantial further expansions. After a conservative Induan‒Carnian phase, teleosts colonize (and persistently occupy) novel regions of morphospace in a predominantly gradual manner until the Hauterivian, after which expansions are rare. Furthermore, apomorphy-defined teleosts possess greater phenotypic variety than typically assumed. Comparison of crown and stem teleost partial disparity indicates that, despite a statistically significant increase in crown teleost disparity between the Late Jurassic and earliest Cretaceous, stem teleosts remained important long-term contributors to overall teleost disparity during this time.
... Ganoine-covered scutes around the anus are not known among stem-group teleosts such as pachycormiforms, aspidorhynchiforms, Prohalecites, and more derived teleosts including Pholidophoridae and other related groups. However, these structures are common among holosteans, such as Semionotiformes, Lepisosteiformes ( Bürgin, 2004;Lombardo and Tintori, 2008;Grande, 2010;Cavin et al., 2013), andMacrosemiiformes (Schultze, 1966;Bartram, 1977;Bravi, 1994;González-Rodríguez and Reynoso, 2004;Arratia and Schultze, 2012). In this character, Teleosteomorpha n. sp. 1 from the La Cantera Formation resembles non-teleosteomorph neopterygians. ...
Scales of a new species of Teleosteomorpha from
the continental Aptian of the south of South America are
studied. These neopterygians are from the La Cantera Formation
in central Argentina, and were previously identified
as Pholidophoriformes. They present ganoid scales; most of
them are rhombic with well-developed peg-and-socket articulations
and possessing a smooth surface. They have a
straight posterior margin, but occasionally, some scales of the
flank have a sinuous posterior margin with one or two serrations.
The shape of the scales varies along the body from
large, rectangular and deeper than long scales behind the
head to the preanal region to smaller and rhomboidal scales
in the caudal region. There are a few horizontal rows along
the flank and about 32 lateral line scales. Thick, round ganoid
scales are present in the prepelvic region close to the ventral
margin. The round and rhombic scales present growth lines,
which form concentric ridges on the external side. A characteristic
row of deep scales forms the dorsal margin on each
side of the body; a row of median ridge scales is not present.
This is a unique feature of the studied fishes. Scutes covered
with unornamented ganoine precede the pelvic, dorsal,
and anal fins, as well as the dorsal and ventral margins of
the caudal fin. The posterior margin of the dorsal lobe of
the caudal fin is formed by a single line of scales, which
continues and covers the base of the first principal caudal
ray. Histological studies reveal a lepisosteoid-scale type with
multiple ganoine layers, lack of dentine, and the presence of
canaliculi of Williamson. The macro- and micromorphology
of the scales shows features that are found in other teleosteomorphs,
but also in other neopterygians.
... Ganoine-covered scutes around the anus are not known among stem-group teleosts such as pachycormiforms, aspidorhynchiforms , Prohalecites, and more derived teleosts including Pholidophoridae and other related groups. However , these structures are common among holosteans, such as Semionotiformes, Lepisosteiformes (Bürgin, 2004; Lombardo and Tintori, 2008; Grande, 2010; Cavin et al., 2013), and Macrosemiiformes (Schultze, 1966; Bartram, 1977; Bravi, 1994; González-Rodríguez and Reynoso, 2004; Arratia and Schultze, 2012). In this character, Teleosteomorpha n. sp. 1 from the La Cantera Formation resembles non-teleosteomorph neoptery- gians. ...
Scales of a new species of Teleosteomorpha from the continental Aptian of
the south of South America are studied. These neopterygians are from the La
Cantera Formation in central Argentina, and were previously identified as
Pholidophoriformes. They present ganoid scales; most of them are rhombic
with well-developed peg-and-socket articulations and possessing a smooth
surface. They have a straight posterior margin, but occasionally, some
scales of the flank have a sinuous posterior margin with one or two
serrations. The shape of the scales varies along the body from large,
rectangular and deeper than long scales behind the head to the preanal
region to smaller and rhomboidal scales in the caudal region. There are a
few horizontal rows along the flank and about 32 lateral line scales. Thick,
round ganoid scales are present in the prepelvic region close to the ventral
margin. The round and rhombic scales present growth lines, which form
concentric ridges on the external side. A characteristic row of deep scales
forms the dorsal margin on each side of the body; a row of median ridge
scales is not present. This is a unique feature of the studied fishes.
Scutes covered with unornamented ganoine precede the pelvic, dorsal, and
anal fins, as well as the dorsal and ventral margins of the caudal fin. The
posterior margin of the dorsal lobe of the caudal fin is formed by a single
line of scales, which continues and covers the base of the first principal
caudal ray. Histological studies reveal a lepisosteoid-scale type with
multiple ganoine layers, lack of dentine, and the presence of canaliculi of
Williamson. The macro- and micromorphology of the scales shows features that
are found in other teleosteomorphs, but also in other neopterygians.
... The short snout and most basal members of this order as it was defined by L opez-Arbarello (2012) and Cavin et al. (2013), also are the oldest taxa; Lepidotes includes only Early Jurassic species; Scheenstia, Isanichthys, and Thaiichthys are Late Jurassic-Early Cretaceous (Neocomian); and Pliodetes and Ararilepidotes are only known from the Early Cretaceous (Albian). In contrast, the long snout, crown, and younger lepisosteiforms are known since the Early Creataceous (Table 1); Obaichthys decoratus Wenz & Brito, 1992; O. africanus Grande, 2010; Dentilepisosteus leavis (Wenz & Brito, 1992); and Atractosteus (Oniichthys) falipoui (Cavin & Brito, 2001) are Early Cretaceous-early Late Cretaceous (from Aptian to Late Cenomanian); the age of Lepisosteus indicus (Woodward, 1890) is Late Cretaceous (Maastrichthian) or Early Paleogene (Paleocene). ...
Herreraichthys coahuilaensis gen. and sp. nov. is described based on a single specimen collected in the Santonian marls strata of the "Los Temporales" quarry, Coahuila State, northern Mexico. This new species shows the diagnostic characters of the Family Lepisosteidae and tribe Lepisosteini, together with Lepisosteus and Atractosteus. This new fish shows two rows of teeth on dentary and lacrimomaxillae bones, including a lingual row of sharp and small regular size teeth, as well as a medial row of longer and fang-like teeth; this also has a lacrimomaxillary series as the main bite element of the upper jaw and the plicidentine structure on teeth. This Mexican fish differs from the other lepisoestinis in two characters; its lacrimomaxillary series is composed of 32 bones that constitute the largest series as far known among lepisosteiformes, and its premaxilla is comparatively wider and shorter. The occurrence of this specimen into an open marine deposit with no freshwater elements suggests that Herreraichthys was a marine inhabitant; however, there is the possibility that this species was able to temporarily survive in the sea, as Atractosteus spatula does now.
... The bulging teeth with a flattened shaft and a hooked apex are pharyngeal teeth. Those with a circular section shaft and curved apex might possibly be oral teeth by comparison with oral teeth of the ginglymodian Thaiichthys buddhabutrensis from basal Cretaceous deposits of Thailand (Cavin, Deesri & Suteethorn, 2013). ...
The vertebrate assemblage from the Early Cretaceous non-marine Xinlong Formation of the Napai Basin, in the south-western part of Guangxi Zhuang Autonomous Region (southern China), is reviewed. The assemblage includes chondrichthyans (at least six species of hybodont sharks including
Hybodus, Thaiodus, Heteroptychodus
and
Acrorhizodus
), actinopterygians (Halecomorphi and Ginglymodi), turtles (the adocid
Shachemys
and the carettochelyid
Kizylkumemys
), crocodilians (cf.
Theriosuchus
) and dinosaurs (the sauropods
Fusuisaurus
and
Liubangosaurus
, carcharodontosaurid and spinosaurid theropods, iguanodontians and a possible psittacosaurid). This assemblage shows many similarities to those from non-marine formations of the Khorat Group of north-eastern Thailand. It seems to be particularly close to that from the Khok Kruat Formation, considered as Aptian in age, as shown especially by sharks and turtles and by the presence of iguanodontians. An Aptian age is therefore proposed for the Xinlong Formation. A study of the stable oxygen and carbon isotope compositions of reptile apatite suggests that this part of South China experienced subtropical arid conditions during the deposition of the Xinlong Formation. In its composition, the vertebrate fauna from the Xinlong Formation seems to be more similar to coeval faunas from SE Asia than to assemblages from northern China (including the Jehol Biota). Although this may partly reflect different depositional and taphonomic environments (fluvial for the Xinlong Formation versus lacustrine for the Jehol Biota) it seems likely that, during Early Cretaceous time, southern China and SE Asia were part of a distinct zoogeographical province, different from that corresponding to northern China. This may be the result of both climatic differences (with relatively cool climates in northern China versus a subtropical climate in the south) and geographical barriers such as mountain chains.
... Differences between the Cherves material and S. mantelli are also observed, such as the suture between both frontals, which is straight in S. mantelli and apparently sinusoidal in the Cherves-de-Cognac taxon. But examination of this feature in a large population of the ginglymodian, Thaiichthys buddhabutrensis from the Lower Cretaceous of Thailand, indicates that the pattern of the suture between paired bones on the skull roof may vary within a species (Cavin et al., 2012). ...
... The largest specimen from this locality, ca. 90 cm in total length, belongs to the genus Isanichthys 2 , but most of the specimens are referred to Thaiichthys buddhabutrensis 3,4 This species has a total length ranging from ca. 40 to 50 cm. In November 2010, a nearly complete fi sh was collected from the Kham Phok locality close to the Kham Phok village, Nong Sung District, Mukdahan Province, located in NE Thailand on the Khorat Plateau ( Figure 1). ...
An isolated articulated specimen referred to Thaiichthys buddhabutrensis from the Kham Phok locality, Phu Kradung Formation, is described. It represents the fi rst occurrence of a juvenile ginglymodian found in the Mesozoic of Thailand. The specimen is approximately 15 cm long, 7 cm wide, and lacks the tail. The head is 3.5 cm long, and 4 cm wide. The ossifi cations of the head have no ornamentation, except small pits for the sensory canal. The squamation is composed of articulated ganoid scales with smooth surface. Only the paired fi ns are present. However, we can estimate the position of the dorsal and anal fi ns by examination of the pattern of the scales along the dorsal ridge and by the position of the unusual shaped anal scale, respectively. The scales show a variety of shape according to their position and some show peg and socket articulations. The size of the specimen is about three times smaller than the common size of the T. buddhabutrensis specimens present in the Phu Nam Jun locality from the Phu Kradung Formation. According to its size and its characteristic, the specimen described herein is referred to a juvenile individual of T. buddhabutrensis.
... A third species, Sangiorgioichthys valmarensis , was recorded from the Late Ladinian Kalkschieferzone (Meride Limestone) of the Monte San Giorgio area, the same unit yielding the type species (Lombardo et al. 2012). Sangiorgioichthys occupies a critical position within the Semionotiformes because it shows several primitive semionotiform characters such as short snout, low number of anterior infraorbitals , the lack of specialized dentition and scale articulation , etc., which adds new information to the early history of the order and helps in establishing character polarities (Tintori & Lombardo 2007; Cavin 2010; López-arbarello et al. 2011; López-arbarello 2012; Cavin et al. 2013). Here, we report on a fourth species of Sangiorgioichthys from the Middle Triassic (Pelsonian, Middle Anisian) vertebrate fossiliferous layers of the upper Member of the Guanling Formation, about 50 m below the base of the overlying Yangliujing Formation, Fig. 1. ...
Sangiorgioichthys yangjuanensis sp. nov., from the Middle Triassic (Pelsonian, Middle Anisian) vertebrate fossiliferous layers of the upper Member of the Guanling Formation in the Dry Well Site, near Yangjuan Village, Panxian County, Guizhou Province, South China, is herein described. The presence of one single anterior infraorbital, a large infraorbital at the posteroventral corner of the orbit, one ventral suborbital covering the quadrate and quadratojugal, small dorsal fin limited to the area between the origin of the pelvic and anal fins supports the generic assignment of the new taxon. Of the known Sangiorgioichthys species, it closely resembles S. sui in having the median part of the supratemporal commissure lodged in the parietals, the presence of a sensory canal entering the posteriormost supraorbital, an elongated supramaxilla fitting in an excavation of the dorsal border of the maxilla, etc., which do not occur in S. aldae and S. valmarensis, although phylogenetic signal of these features are pending. The new taxon differs from S. sui in the number of dorsal suborbitals, the structure and row number of the scales, and also the dermosphenotic dorso-ventrally elongated, rectangular in shape, with the temporal canal entering the element at the dorsal half, then turning ventrally into the infraorbital canal rather than going posterior to the supraorbital canal.
... The association of hemispherical teeth with a central ''wart'', hook-like pharyngeal teeth, and scales with a smooth layer of ganoine is suggestive of Lepidotes (Mudroch & Thies, 1996). Therefore, we identify these specimens as Lepidotes sp., even though we do not ignore the systematic issues surrounding this genus (see e.g., Ló pez-Arbarello, 2012; Cavin et al., 2013). Lepidotes has been signaled at St. Martin (Knoll et al., 2013: fig. ...
The palaeontological content (charophytes and vertebrates) of organic-rich layers from the Middle Jurassic (Bathonian) of the Grands Causses at Mostuéjouls (Aveyron, France) has been examined. It is rich in gyrogonites of Porochara douzensis. The vertebrates of the lower layer include a single hybodontiform tooth, “semionotiform” teeth and scales, and one pycnodontiform tooth whereas the upper layer has yielded one hybodontiform tooth, a variety of actinopterygian remains (mostly Caturus sp. and indeterminate pycnodontiforms) and a few possible reptile remains. The variation in fauna between the two layers is ascribed to a different degree of marine influence.
... Ginglymodian fishes have an extensive fossil record, and so branch lengths were determined based on imposed nodal constraints derived from the age and phylogenetic position of fossil taxa. Vertebral count data were taken from [28,7576777879. Vertebral count data were extrapolated from scale-row counts in fossil forms, with the anterior insertion of the anal fin corresponding to the abdominal – caudal transition. This approach is supported by osteological data [28], which indicates that vertebral counts and scale row counts are generally similar , as is also indicated by dissections [80]. ...
A long, slender body plan characterized by an elongate antorbital region and posterior displacement of the unpaired fins has evolved multiple times within ray-finned fishes, and is associated with ambush predation. The axial skeleton of ray-finned fishes is divided into abdominal and caudal regions, considered to be evolutionary modules. In this study, we test whether the convergent evolution of the ambush predator body plan is associated with predictable, regional changes in the axial skeleton, specifically whether the abdominal region is preferentially lengthened relative to the caudal region through the addition of vertebrae. We test this hypothesis in seven clades showing convergent evolution of this body plan, examining abdominal and caudal vertebral counts in over 300 living and fossil species. In four of these clades, we also examined the relationship between the fineness ratio and vertebral regionalization using phylogenetic independent contrasts.
We report that in five of the clades surveyed, Lepisosteidae, Esocidae, Belonidae, Sphyraenidae and Fistulariidae, vertebrae are added preferentially to the abdominal region. In Lepisosteidae, Esocidae, and Belonidae, increasing abdominal vertebral count was also significantly related to increasing fineness ratio, a measure of elongation. Two clades did not preferentially add abdominal vertebrae: Saurichthyidae and Aulostomidae. Both of these groups show the development of a novel caudal region anterior to the insertion of the anal fin, morphologically differentiated from more posterior caudal vertebrae.
The preferential addition of abdominal vertebrae in fishes with an elongate body shape is consistent with the existence of a conservative positioning module formed by the boundary between the abdominal and caudal vertebral regions and the anterior insertion of the anal fin. Dissociation of this module is possible, although less probable than changes in the independently evolving abdominal region. Dissociation of the axial skeleton-median fin module leads to increased regionalization within the caudal vertebral column, something that has evolved several times in bony fishes, and may be homologous with the sacral region of tetrapods. These results suggest that modularity of the axial skeleton may result in somewhat predictable evolutionary outcomes in bony fishes.
... Here we do not consider Ginglymodi as this clade has been recently exhaustively discussed and is very well supported in our analysis by numerous synapomorphies [3,20,21] (bootstrap value equals 98). ...
Based on specimens from the Lower Cretaceous Tlayua Formation of Mexico, we describe a new genus and species of Halecomorphi, Cipactlichthysscutatus gen. et sp. nov, which exhibits several diagnostic characters such as the dermal bones and the scales with ganoin and highly ornamented by numerous tubercles and ridges; parietal slightly longer than wide with approximately the same length as the frontal; jaws extending far, below the posterior orbital margin, reaching the posterior third of the postorbital plate; maxilla with a convexly rounded posterior margin; pectoral fin margins slightly convex; first ray of pectoral fin very long, reaching the posterior edge of the pelvic fin; about 37 preural vertebrae and 7 Ural centra; a series of hypertrophied scales just posterior to the cleithrum; arrangement of flank scales with two rows of deep scales; a series of dorsal and ventral scutes forming the dorsal and ventral midline, between the dorsal and anal fins and the caudal fin. A phylogenetic analysis including two outgroups and eleven neopterygians confirmed the monophyly of the Holostei as well as the monophyly of the Halecomorphi, although this last clade is weakly supported. Cipactlichthysscutatus was hypothesised as the sister-group of the (Ionoscopiformes + Amiiformes).
Chrysemys, commonly known as painted turtles, have the largest native biogeographic range of all North American turtles. The presence of a new species, Chrysemys corniculata sp. nov., in the Late Hemphillian-Early Blancan North American Land Mammal Age (latest Miocene-Early Pliocene) of Tennessee provides further data on the evolution of Chrysemys, deirochelyines and emydids. The new fossil species lies basally in Deirochelyinae and suggests that either Chrysemys represents a basal deirochelyine morphology and is one of the oldest genera in the family, or that similar basal morphologies have evolved multiple times throughout deirochelyine evolution. Its occurrence at the same time as Chrysemys picta, during the Hemphillian-Early Blancan, a time of high biodiversity in emydid turtles, suggests either multiple species of Chrysemys during the Late Hemphillian-Early Blancan (at least one in the mid-west and one farther east), or multiple lineages with basal morphologies during this time. Early fossil deirochelyines occur after the greenhouse conditions of the Eocene and the Mid-Miocene Climatic Optimum. Vicariance led to deirochelyines becoming more speciose, including the occurrence of C. corniculata, after the Mid-Miocene Climatic Optimum, potentially suggesting cooler temperatures aided in the evolution of the subfamily and their speciation during the Hemphillian and into the Early Blancan.
Semionotiformes is a diverse extinct group in Neopterygii. It is well represented in the Mesozoic, occurring in marine and continental strata worldwide. However, some diagnostic characters of Semionotiformes and, in particular, of Semionotidae, have been under debate, due to the description of new taxa or revision of previously known ones. In this paper, we provide a detailed description of the first unequivocal record of Semionotidae from Gondwana, i.e., Lophionotus parnaibensis, sp. nov. from the Pastos Bons Formation, Upper Jurassic, in the Parnaíba Basin, northeastern Brazil. It was included in the genus Lophionotus mainly due to the presence of smooth cranial bones, triangular lateral expansion of antorbital portion of frontal, and ratio length/width of frontals lower than three times. It was recovered as a new species due to a unique combination of characters. This discovery represents the most recent occurrence of the genus, which was previously recorded only in the U.S.A. up to the Early Jurassic.
The extinct ray-finned fish taxon Robustichthys luopingensis from Luoping, eastern Yunnan, China represents the largest holostean known in the Middle Triassic. Despite its potential significance for investigating the holostean phylogeny and reconstructing the Triassic marine ecosystems, Robustichthys has so far not been described in detail and its phylogenetic position within the Holostei was controversy. This study provides a redescription and revision of Robustichthys based upon a comparative study of eight type specimens and nine new specimens. Newly recognized information includes a toothed parasphenoid, a pair of premaxillae not pierced by the olfactory nerve, a splint-like quadratojugal, a hatchet-shaped hyomandibula, an hourglass-shaped symplectic, anterior and posterior ceratohyals, a complete series of branchiostegal rays, and sclerotic bones. A revised reconstruction of Robustichthys is presented. Results of a cladistic analysis confirmed Robustichthys as an ionoscopiform within the Halecomorphi; the previous placements of Robustichthys as a basal ginglymodian and Ionoscopidae as a basal amiiform clade are not supported. The sister group relationship between Sinamiinae (Sinamia and Ikechaoamia) and Amiinae (Amia and Cyclurus) within the Amiidae is newly recognized. This revised topology provides new insights into the evolution and historical paleoecology of halecomorph fishes.
A series of well-preserved fossil assemblages from the Middle Triassic marine rock succession in Southwest China provide unique evidences for studying the early evolution of holostean fishes, including Halecomorphi (e.g., bownfin) and Ginglymodi (e.g., gars). Ginglymodi have the earliest record in the early Middle Triassic (Anisian, ~244 Ma) of China, represented by Kyphosichthys and Sangiorgioichthys sui from Yunnan and S. yangjuanensis from Guizhou. Here, we report the discovery of a new ginglymodian, Fuyuanichthys wangi gen. et sp. nov., based on 22 well-preserved specimens from the lower part of the Zhuganpo member of the Falang Formation in eastern Yunnan and western Guizhou, which documents the first discovery of convincing ginglymodians from the late Middle Triassic (Ladinian, ~240 Ma) Xingyi biota in China. Fuyuanichthys possesses a unique combination of features that easily distinguishes it from other ginglymodians, such as presence of a median gular and short and edentulous maxillae, and absence of a supramaxilla and supraorbitals. As one of the smallest known ginglymodians with a maximum standard length of ~75 mm, the new finding further supports that the Middle Triassic Ginglymodi have a relatively small range of body sizes compared with the Halecomorphi from the same ecosystems in China. Results of a phylogenetic analysis recover Fuyuanichthys as a sister taxon to Kyphosichthys at the ginglymodian stem, and provide new insights into the early evolution of this clade.
Lepisosteoids are known for their evolutionary conservatism, and their body plan can be traced at least as far back as the Early Cretaceous, by which point two families had diverged: Lepisosteidae, known since the Late Cretaceous and including all living species and various fossils from all continents, except Antarctica and Australia, and Obaichthyidae, restricted to the Cretaceous of northeastern Brazil and Morocco. Until now, the oldest known lepisosteoids were the obaichthyids, which show general neopterygian features lost or transformed in lepisosteids. Here we describe the earliest known lepisosteoid (Nhanulepisosteus mexicanus gen. and sp. nov.) from the Upper Jurassic (Kimmeridgian - about 157 Myr), of the Tlaxiaco Basin, Mexico. The new taxon is based on disarticulated cranial pieces, preserved three-dimensionally, as well as on scales. Nhanulepisosteus is recovered as the sister taxon of the rest of the Lepisosteidae. This extends the chronological range of lepisosteoids by about 46 Myr and of the lepisosteids by about 57 Myr, and fills a major morphological gap in current understanding the early diversification of this group.
The hump-backed ginglymodian fish Kyphosichthys grandei, from the Anisian (Middle Triassic) of South China, is re-described. The revised description presents much previously unknown or misidentified anatomical information, such as the presence of a median gular plate; a short, broad, squarish rostral; two pairs of extrascapulars, of which the lateral one is fused with the parietal bone; parasphenoid having relatively large, dorsoposteriorly oriented ascending processes which articulate with the sphenotics; a complete row of scales bordering the body lobe; and supracleithrum with a concave facet for articulation with the posttemporal, etc. Taxonomical comparison clearly distinguishes Kyphosichthys from other known hump-backed ginglymodians – that is, Luoxiongichthys, Lophionotus, Semiolepis and Paralepidotus – and a potential stem-group ginglymodian Dapedium. A more comprehensive cladistic analysis of the Ginglymodi is conducted herein based on incorporation of more morphological characters and taxa, and rectification of the character states of some taxa used in previous analyses after re-description of Kyphosichthys grandei and better knowledge of Luoxiongichthys hyperdorsalis and Sangiorgioichthys sui based on our observations of specimens at the Geological Museum of Peking University, Beijing, China. The results of our analysis produce the most completely resolved and best-supported hypothesis for the monophyletic group Semionotiformes to date, and also support a new hypothesis that the Middle Triassic ginglymodians Luoxiongichthys, Sangiorgioichthys and Kyphosichthys form a monophyletic group at the base of the Ginglymodi, of which Kyphosichthys grandei is the sister group of Sangiorgioichthys sui. The new family Kyphosichthyidae is introduced. The present contribution supplements previous analyses of the Ginglymodi, especially for basal taxa and the clade Semionotiformes, and sheds new light on the origin and early diversification of the Ginglymodi.
http://zoobank.org/urn:lsid:zoobank.org:pub:C8ACA263-8658-4A66-BFF9-99F6D5C84E91
Significance
The success of teleost fishes, which represent roughly half of all vertebrate species, has attracted attention since Darwin. Numerous scenarios invoke elevated diversification in teleosts facilitated by supposed key innovations, yet claims of teleost exceptionalism are profoundly biased by the evolutionary “snapshot” of living fishes. Analysis of 160 million y (Permian–Early Cretaceous) of evolution in neopterygian fishes reveals that anatomical diversification in Mesozoic teleosts as a whole differed little from their “living fossil” holostean sister group. There is some evidence for evolutionary heterogeneity within teleosts, with early evolving lineages showing the greatest capacity for evolutionary innovation in body shape among Mesozoic neopterygians, whereas members of the modern teleost radiation show higher rates of shape evolution.
The new neopterygian genus Ticinolepis, including two new species T. longaeva and T. crassidens is described from Middle Triassic carbonate platform deposits of the Monte San Giorgio. The anatomy of this fish shows a mosaic of halecomorph and ginglymodian characters and, thus, the new taxon probably represents a basal holostean. During the latest Anisian to earliest Ladinian the two new species coexisted in the intraplatform basin represented by the uppermost Besano Formation, but only T. longaeva sp. nov. inhabited the more restricted basin represented by the Ladinian Meride Limestone (except for the Kalkschieferzone). The more widely distributed type species shows interesting patterns of intraspecific variation including ontogenetic changes and morphological variation over time. The second species presents anatomical features that strongly indicate a strictly durophagous diet. The different distribution of the species is interpreted as a result of habitat partitioning and different adaptability to palaeoenvironmental changes.
In 1963, N. Tabaste described disconnected fossil material from the Saharan Cenomanian site of Gara Tabroumit, and especially three sets of isolated scales that she all referred to the genus Lepidotes. Although the rhomboid shape and overall morphology of one set of scales allow regarding them as ganoid scales, the external aspect of the ganoine is not as regularly smooth and shiny as it is in most lepidosteoid scales commonly referred to ginglymodian ("semionotiform") fishes. A photonic microscopic study of scale ground sections definitively excludes the allocation. of these scales to the genus Lepidotes, or to closely related genera, because of an interrupted ganoine layer, and, more generally to ginglymodians: i) the bony basal plate is deprived of Williamson's canaliculi, which characterized holostean scales; ii) the basal plate is well vascularised and overlaid by a thick layer of dentine; iii) there is an elasmodine layer between dentine and the basal plate. These various histomorphologic characters allow us to consider these ridged scales as belonging to a polypteriform fish, probably Bawitius. The histological specificities of the two other scale series allow their allocation to holostean taxa, respectively to "Lepidotes"pankowskii and to Obaichthys africanus. A new generic name, Adrianaichthys, is coined for "Lepidotes" pankowskii.
This paper provides the first geological and paleontological data of Yosobé and La Lobera, two Late Jurassic vertebrate localities; both localities are part of the marine deposits of the Tlaxiaco Basin, near Tlaxiaco, Oaxaca, Mexico. La Lobera may be included in Cerro de Titania, a historical invertebrate locality inaccurately described, whose Oxfordian-Early Kimmeridgian limestone and marl strata are informally known as “Caliza con Cidaris”. La Lobera contains the typical “Caliza con Cidaris” fossils and the remains of a single fish attributable to the genus Scheenstia. Yosobé is a fossiliferous outcrop belonging in the Late Jurassic (Kimmeridgian-Tithonian) bituminous shale strata informally known as Sabinal formation. The fossil assemblage from Yosobé includes microfossils, plants, invertebrates, and vertebrates, many of which are totally or partially tridimensionally preserved within nodules. Yosobé is the most important vertebrate locality along the entire Tlaxiaco Basin due to a highly abundant and diverse grouping of fishes and reptiles. The fossil assemblage from Yosobé reported in this paper includes the first and most inclusive regional record of taxa such as the first North American Pleuropholidae fish, the first Mexican Jurassic Planohybodus shark, the most complete specimens of the pycnodont Gyrodus in Mexico and the Caribbean, ichthyosaurs, thalattosuchian crocodyliforms, turtles, and pliosaurids in a single locality in the Hispanic Corridor. Present and future descriptive and systematic studies on some fossils from these localities may have important paleobiogeographic and phylogenetic implications worldwide.
The early history of the Semionotiformes is still scarcely known as, apart from the Permian Acentrophorus, most of the Early and Middle Triassic taxa traditionally ascribed to this order are often poorly known and/or they actually belong to other groups. Sangiorgioichthys aldae gen. n. sp. n. is described from the Upper Ladinian Kalkschieferzone (Upper Meride Limestone) of the Monte San Giorgio area on specimens coming from both Italy and Switzerland. The new genus is ascribed to the family Semionotidae as it shows several of the characters usually considered as diagnostic of the family itself, even if no real synapomorphies have been so far proposed for it. As a Semionotidae, Sangiorgioichthys gen. n. has an almost complete circumorbital series, large ascending process of the premaxilla, rostral and nasals almost tube-like, short maxilla, several suborbital bones posterior and ventral to the infraorbitals, long antero-dorsal process of the suboperculum, sensory canal system very rich in pores, mid dorsal ridge scales with an incipient spine. Peculiar characters of the new genus are dermal skull bones completely covered by ganoine, a very large ventral infraorbital almost attaining the anterior edge of the preoperculum, two 'ventral' suborbitals, very elongate anterior supraorbital bone, dentition made of a number of tiny pencil-like teeth, anterior and posterior lateral line scales differentiated.
We report on a new species of the neopterygian genus Sangiorgioichthys Tintori and Lombardo, 2007, from middle Ani-sian (Pelsonian) deposits in South China (Luoping County, Yunnan Province). Sangiorgioichthys was previously known from a single species, S. aldae, from the late Ladinian of the Monte San Giorgio (Italy and Switzerland). The recognition of the new species helped to improve the diagnosis of the genus, which is mainly characterized by the presence of broad posttemporal and supracleithral bones, one or two suborbital bones occupying a triangular area ventral to the infraorbital bones and lateral to the quadrate, and elongate supramaxilla fitting in a an excavation of the dorsal border of the maxilla. Sangiorgioichthys sui n. sp. differs from the type species in having two pairs of extrascapular bones, the medial pair usu-ally fused to the parietals, maxilla with a complete row of small conical teeth, long supramaxilla, more than half of the length of the maxilla, only two large suborbital bones posterior to the orbit, and flank scales with finely serrated posterior borders. With the discovery of S. sui n. sp., the number of fish genera shared by the Anisian/Ladinian deposits in the Alps and the Anisian deposits in South China increases, including not only the cosmopolitan Birgeria and Saurichthys, but also, among others, the subholosteans Colobodus (so far only in Panxian), Luopingichthys (so far only in Luoping), Peltopleu-rus, Habroichthys, and the very specialized neopterygians Placopleurus and Marcopoloichthys (only in Luoping). There-fore, although several fish taxa remain to be studied in the Chinese faunas, the so far available evidence indicates close biogeographic relationship between the Middle Triassic marine faunas of the Western Tethys region.
The comparative osteology, phylogenetic relationships and historical biogeography of all known fossil and living gars (Ginglymodi Lepisosteiformes) are investigated in detail Clearly documented comparative data on the skeletons of lepisosteiforms and closely related taxa are examined with regard to phylogeny, ontogeny historical biogeography stratigraphic paleontology and paleoecology This study of lepisosteiform fishes is also used as a platform to explore several fundamental methodological and philisophical concepts important to phylogenetic/evolutionary investigations (pp 819-828) The seven extant species of gars are the sole surviving members of a formerly diverse division of fishes Ginglymodi (here including Lepisosteiformes dagger Semionotiformes and dagger Macroseminformes) Even Lepisosteiformes (the ginglymodin subgroup that is the focus of this study) was much more diverse taxonomically and morphologically during Mesozoic and Paleogene times than it is today It was also much mole geographically widespread Lepisosteiformes, as defined here, are those neopterygian fishes with opisthocoelous vertebral centra, 'tongue bones" (a basihyal tooth plate consisting of bony plates or entoglossals) dorsal fin set far posterior on body (predorsal length of 75-88% of standard length) and several other uniquely derived morphological characters To set the style and terminology for description of the fossil taxa and to present a fresh look at the osteology and development of living gars the skeletal anatomy of Lepisosteus osseus and Atractostcus spatula is redescribed in great detail and the other five extant gars in somewhat less but still significant detail, all using modern methods of preparation and illustration Such detailed study of the extant species was necessary to adequately interpret probable intraspecific variation and ontogenic variation in fossil taxa Individual variation of both bone morphology and developmental timing in Lepisosteus osseus is also examined The order Lepisosteiformes (gars) is classified into two families here Lepisosteidae (including Lepisosteus Atractosteus, dagger Cuneatus gen nov,, and dagger Masillosteus) and dagger Obarchthyidae fam nov (including dagger Obatchthys and dagger Dentileptsosteus gen nov) The genera dagger Cuneatus gen nov and dagger Masillosteus show a diversity of extinct very short-snouted lepisosteid gars that lived in the Eocene One group (dagger Masillosteus) had very few sharply pointed teeth but the coronoids and upper jaw bones were covered with large flat tipped (styliform) teeth suitable for crushing snails or other shelled organisms dagger Obaichthyidae fam nov represents a family of South American/African gars that unlike Lepisosteidae have a well-developed interopercle, an intercalar fused to the exoccipital, and other features showing basal lepisosteiform morphology to be quite different than was previously thought Acid transfer preparations of dagger obaichthyids from the Upper Cretaceous Santana Formation of Brazil show many previously undescribed morphological details of those taxa that are key to basal neopterygian phylogenetic studies One of the results of new information on basal lepisosteiform morphology is that Holostei (rather than Halecostomi) appears to be a monophyletic group based on morphological data (reported briefly in Grande 2005) Previous phylogenetic studies regarding the classic gar Amta-teleost problem are reviewed (i e the 'Halecostomi vs Holostei controversy) and the characters used to support Halecostomi in those studies are evaluated With the morphological evidence now pointing to Holostei morphological and molecular evidence are now in agreement on the issue The Superdivision Holostei (as used here) includes the Divisions Halecomorphi and Ginglymodi Ginglymodi here includes at least the orders Lepisosteiformes dagger Semionotiformes (dagger Sennonotuv elegans as used here for outgroup comparison) and dagger Macrosemiflormes (dagger Macrosemndae sensu Bartiam 1977) The order dagger Semionotifoimes is still in need of rigorous review and revision to determine which taxa can be included with the type genus without making the order nonmonophyletic Accurate resolution of the Holostei vs Halecostomi problem helps calibrate the basal interrelationships of Neopterygn, a taxon containing nearly half of all living vertebrate species Establishing this pattern of relationship will have ramifications for the general phylogenetic studies within Neopterygn and for studies that use Neopterygn for outgroup comparison This study also demonstrates the power of a fossil taxon to help overturn a phylogenetic pattern derived from the morphology of extant species Much of what tipped the scale away from a monophyletic Halecostomi and toward a monophyletic Holostei in this study is the morphological evidence described here for the Cretaceous dagger Obaichthyidae (fam nov) dagger Obaichthyids are clearly lepisosteiforms based on numerous characters, but they have a well-developed interopercle and other features that falsify previously proposed synapomorphies for the monophyly of Halecostomi These critical characters were missed in previous descriptions of dagger Obatchthys because of a lack of adequately prepared specimens dagger Obaichthyids represent a phylogenetic "missing link in the truest sense of the term Numerous general methodological, philosophical and theoretical concepts are discussed in this paper (which can be located using either the Subject Index or the Table of Contents), including the concept of the "effective type" specimen, the concept of the "effective type" genus for taxonomic names above family level rank the use of quotation marks to indicate uncertain taxonomic designation, philisophical roots of the comparative technique, the importance of stages of disarticulation in interpreting the morphology of fossil taxa, anatomical terminology as a tool, relative empiricism, missing data, data partitioning, and the meaning of cladograms Once again I apply what was previously (Grande and Bemis, 1998) termed an empirical synthetic pattern approach" to an investigation of a basal neopterygian group (Lepisosteiformes) although in the end, that approach is nothing more than a fancy name for good comparative biology
Several hypotheses supporting monophyly of the Teleostei on the basis of synapomorphies have been produced over the last 30 years. The concept of Teleostei sensu Patterson (1977) and Patterson and Rosen (1977), with halecomorphs as the sister-group and †Pachycormiformes and †Aspidorhynchiformes at the base, has been questioned recently. A new hypothesis has been suggested (Arratia, 1999, 2000a) with †Pholidophorus as the basal taxon. Whereas the monophyly of Teleostei has been supported by numerous investigations based on morphological evidence of fossil and living forms and on molecular data, the sister-group of Teleostei is still unresolved. Possible sister-groups are the Amiiformes, Lepisosteiformes, †Dapedium, †Pycnodontiformes, †Pachycormiformes, and †Aspidorhynchiformes. Their relative positions in the cladogram changes when different outgroups are used.The large actinopterygian clade comprising the stem-groups of teleosts and the Teleostei (including fossil and extant members) and excluding the Halecomorphi (Amia and relatives) and the Ginglymodi (Lepisosteus and relatives) is formally named Teleosteomorpha. The name Teleostei is reserved here for the apomorphy-based taxon Teleostei that includes the fossil basal teleosts and the Teleocephala (crown-group). The monophyly of Teleostei is supported by one uniquely derived character and numerous homoplasious derived characters.The available information reveals that there is no correlation between the age of the probable sister-groups of Teleostei and their primitiveness. All of them appeared at the same time as the Teleostei (e.g., †Pycnodontiformes) or are younger (e.g., Amiiformes, Lepisosteiformes, †Dapedium, †Pachycormiformes, and †Aspidorhynchiformes).The closest living (Amia or Lepisosteus) and the closest fossil sister-group of teleosts remains unknown.
The comparative osteology, phylogenetic relationships, and historical biogeography of all known taxa of fossil and living amiid fishes (Halecomorphi: Amiidae) are investigated in detail. Previously, the detailed osteology of nearly all fossil amiids was unknown. We present the first well-supported comprehensive phylogeny for fossil and living amiid fishes. We synthesize clearly documented phylogenetic data on amiids and other halecomorph fishes with other historical phenomena such as ontogeny, historical biogeography, stratigraphic paleontology, and paleoecology (both “stationary” and “historical”). We also use our study of halecomorph fishes as a platform to explore several fundamental methodological and theoretical concepts important to phylogenetic/evolutionary investigations. These concepts pertain mainly to (1) the use of comparative empirical data to interpret various historical patterns and (2) the practice of integrating fossil and living species together in original (i.e., non-literature-based) phylogenetic studies.As proposed by Patterson (1973), Amia calva is the sole surviving member of a formerly diverse clade, Halecomorphi. Even Amiidae (the halecomorph subgroup that is the focus of this study) was taxonomically diverse and widespread during Mesozoic and Paleogene times. Amiidae here includes only those amiiform fishes that have solid perichordally ossified diplospondylous centra of both the “normal” (a term used here for non-alternating) and the alternating type in the caudal region. Consequently, †Sinamiidae and †Caturoidea (†Caturidae plus †Liodesmidae) are excluded from the family Amiidae. To set the style and terminology for description of the fossil taxa, and to present a fresh look at the osteology and development of the only living amiiform, we redescribe Amia calva in detail using modern methods of preparation and illustration. Detailed study of Amia calva is critical for interpreting probable intraspecific variation and ontogeny in fossil skeletons. We examined individual variation of both bone morphology and developmental timing in Amia calva.We classify the family Amiidae into four subfamilies here: †Amiinae (including †Amia, †Cyclurus, †Pseudamiatus, and † “Amia” hesperia), †Vidalamiinae subfam. nov. (including † Vidalamia, †Pachyamia, †Melvius, †Calamopleurus, and †Maliamia), †Solnhofenamiinae subfam. nov. (including †Solnhofenamia gen. nov.), and †Amiopsinae subfam. nov. (including †Amiopsis). The genus †Nipponamia remains Amiidae subfamily indeterminate until additional material can be found and studied, although it does not appear to belong to Amiinae or †Amiopsinae subfam. nov. as defined here. Other nominal genera of Amiidae are discussed as nomina nuda or nomina dubia.We found Amiinae to be a clearly monophyletic group diagnosed by numerous synapomorphic characters. This is the only amiid (and halecomorph) subfamily known to have survived beyond the early Eoccne. It was a diverse group with a known stratigraphic range of Late Cretaceous through the present. The earliest diagnosable species in the subfamily is †Cyclurus fragosus from the upper Maastrichtian of Alberta, Canada, and the earliest Amiinae indeterminate is a collection of fragments from the upper Cenomanian of Uzbekhistan (“?Amia semimarina” Nessov 1985, a nomen dubium). Earlier forms reported by Boreske (1974) could not be verified as Amiinae. Amiinae was widespread and particularly speciose during the Eocene, and appears to have been confined almost exclusively to fresh water. The extremely rare amiine fossil fragments from brackish water deposits probably represent accidental or, at most, occasional migration into brackish environments or possibly entrapment in a drying water system. Amiinae includes three valid species of Amia (including †A. pattersoni sp. nov.), eight valid species of †Cyclurus (all of which are described here), and † “Amia” hesperia (a valid species of uncertain generic affinity). It also includes the genus †Pseudamiatus which remains †Amiinae indeterminate, until the type and only known specimen can be further prepared or until additional material can be found. It probably belongs in Amia or †Cyclurus as those genera are defined here. We also review more than 30 other nominal species of amiines, all of which we believe are invalid names (either nomina dubia, nominanuda, or subjective junior synonyms) but some of which nevertheless extend the stratigraphic and geographic range of the subfamily Amiinae. Although we clarify the known diversity and monophyly of Amiinae, and add new morphological information about numerous amiine species, further materials and work are needed to resolve phylogenetic interrelationships within this subfamily.†Vidalamiinae subfam. nov. is a previously unrecognized, diverse group of amiid taxa, several of which reach very large sizes (to about two meters total length). This well-supported monophyletic subfamily is known only from the Early Cretaceous to the early Eocene, and contains two well-supported monophyletic subgroups: †Vidalamiini tribe nov. and †Calamopleurini tribe nov. These tribes have interesting biogeographic distributions that seem incongruent with today's geography, but these distributions make intuitive sense given current interpretations of the paleogeography of the Early Cretaceous (illustrated here). †Vidalamiini tribe nov. includes †Vidalamia (one species from coastal estuarine/lagoonal deposits of Spain), †Pachyamia (two species: one from marine deposits of the Middle East and a new species from marine deposits in Mexico) and †Melvius (two species from deposits along the margin of the Upper Cretaceous North American Seaway). During the Early Cretaceous, this seemingly far-flung distribution was connected by a continuous shallow marine continental margin and seaway. All five species of †Vidalamiini tribe nov. are described in detail here. †Calamopleurini tribe nov. includes †Calamopleurus (three species: one from an inconclusively determined paleoenvironment of eastern Brazil, one species from a probable freshwater paleoenvironment of eastern Brazil, and a new species from a yet unknown paleoenvironment of Morocco) and †Maliamia (one species from west-central Africa in deposits of unknown water chemistry). Most of these species (particularly †C. cylindricus) are described in detail here. †Vidalamiinae subfam. nov. is the sister group to Amiinae, and the two subfamilies together form the supersubfamily Amiista nuper interposita. The term “nuper interposita” is introduced here to indicate the first published use of new names inserted between existing family group names.†Solnhofenamiinae subfam. nov. is a Late Jurassic marine group from Europe (Germany and France) currently containing a single species, †Solnhofenamia elongata gen. nov. This species was formerly placed in the genus † Urocles as † “Urocles” elongatus. However, the genus † Urocles is invalid in our scheme because the type species of †Urocles is congeneric with †Amiopsis, and the name †Amiopsis has priority. We find that † “Urocles” elongatus is more closely related to a group containing Amiinae plus †Vidalamiinae subfam. nov., than it is to the type species of the genus †Urocles (= †Amiopsis lepidota here). Therefore, we place †“Urocles” elongatus in the new genus †Solnhofenamia. Because †S. elongata gen. nov. is the sister group to a group containing Amiinae plus †Vidalamiinae subfam. nov., we put it into †Solnhofenamiinae subfam. nov. We describe this species in detail for the first time.†Amiopsinae subfam. nov. is a poorly supported stem group of amiids from Late Jurassic to late Cretaceous (Turonian) marine and freshwater deposits of Europe (Yugoslavia, Germany, Spain, England, Belgium, and possibly France). This group, with five valid species, may be non-monophyletic. †Amiopsinae subfam. nov. contains most of the amiids excluded from the hypersubfamily Amiida nuper interposita, a monophyletic group containing ((Amiinae + †Vidalamiinae subfam. nov.) + †Solnhofenamiinae subfam. nov.). All five species of †Amiopsis are described here with much new detail.The phylogenetic position and biogeographic significance of the single known, poorly preserved specimen of †Nipponamia, from Early Cretaceous freshwater deposits of Japan, is largely unknown. Additional material is needed to better understand its morphology.In addition to our cladogram of Amiidae, we produced a cladogram of Halecomorphi. Our sample of non-amiid halecomorph taxa was far less complete than our sample of amiid taxa; nevertheless we found several well-supported nodes within non-amiid halecomorphs which can serve as general guides for future research.We discuss numerous general methodological, philosophical, and theoretical concepts in this paper, including the construction of taxonomic diagnoses, the treatment of undiagnosable taxa, and the treatment of ontogenetically variable characters. We review the effects on phylogenetic analysis of problematic (e.g., “missing”) data entries resulting from either problematic taxa (e.g., highly incomplete fossil taxa) or problematic characters (characters whose states are unknown for most taxa). Various types of problematic data are also reviewed. We discuss the exclusion of certain problematic taxa (here termed “inserted” taxa) and problematic characters (here termed “mapped” characters) from phylogenetic analyses. We also examine the effects of phylogenetically “redundant” taxa and consider the comparative value of wellresolved nodes versus completely resolved trees in cladistic studies. These concepts and terms can all be located in this volume by using the table of contents or the subject index.Our study exemplifies the large amount of natural historical information that can be interpreted from multidisciplinary pattern studies of fossil and living actinopterygian fishes. We term our general approach to the study of natural history as “an empirical synthetic pattern approach”, an exploratory method whose fundamentals go back to the 19 century naturalist Louis Agassiz (1807–1873). Many other actinopterygian groups of equal potential remain virtually unstudied with regard to their broad historical significance (e.g., phylogenetic pattern congruence between comparative morphology, ontogeny, biogeography, and stratigraphy). Exceptional preservation and abundant poorly known material make fossil actinopterygians one of the greatest remaining frontiers in vertebrate paleontology.
Lepidotes gloriae, sp. nov. (Actinopterygii: Semionotiformes) from the Late Jurassic of Western Cuba is described. The skeletal anatomy of this fish shows two features previously unknown in Lepidotes Agassiz, 1832: 1) presence of two pairs of ectopterygoids and 2) presence of dermometapterygoids. Skeletal elements whose structure is little known or even unknown in other species of Lepidotes have been studied in detail in L. gloriae: 1) branchial tooth plates, 2) endoskeletal shoulder girdle, 3) posttemporal, 4) clavicle, 5) pelvic girdle, and 6) caudal fin skeleton. The sensory canal system on the head of L. gloriae is unique among other species of Lepidotes in having the median part of the supratemporal commissure enclosed within the parietals, in having a medio-anteriorly directed branch of the infraorbital canal behind the orbit reaching from the dermopterotic into the frontal, and in having the ventral part of the median pit line of the skull roof replaced by a short canal traversing the dermopterotic. The cranial sensory canal system is unique among actinopterygians in having developed an oral canal dorsal to the mandibular canal in the anterior part of the dentalosplenial.
Most Mesozoic vertebrate species are represented by scarce and incomplete specimens, preventing statistical studies of morphometric features. Moreover, rich vertebrate assemblages are rarely excavated in conditions that allow taphonomical studies. Lepidotes buddhabutrensis is a common species found in the Late Jurassic-Early Cretaceous locality of Phu Nam Jun, Phu Kradung Formation, in NE Thailand. Individuals, collected during systematic excavation since 2002, show great variations in preservation states and body postures. In this paper we study the mode of variation of morphometric features of the fish population, the growth mode, and the relationship between morphology and size. We assess the range of variation in preservation and taphonomy, based on arbitrarily defined scales, to test if vertical variations occur in the sample of individuals within the site. We test possible favoured orientation of specimens within the assemblage. In contrast to preliminary field observations, statistical analyses show that all individuals belong to a single Gaussian population and that gross morphological shape variations are related only to size during fish growth. L. buddhabutrensis shows a positive allometric growth for the pectoral to dorsal, and pectoral to anal fin distances, and a negative allometric growth for the unpaired fins (dorsal and anal fins lengths). We detected no relationships between the vertical location of the fishes within the fossiliferous deposit and the body shape of the specimens, nor between the state of preservation and the taphonomy, but there are significant differences in the state of preservation according to the position of the fishes in the fossiliferous deposit. The occurrence of a single Gaussian population and the absence of morphological and preservational variations through the depositional column are evidence that the fish assemblage is probably the result of a single mass mortality event. The apparent diversity in morphology is probably due to variations in the mode of preservation. The fish appear to have been oriented by a current at the time of deposition at the top of the fossiliferous deposit only.
We describe the morphology of Semionotus, focusing on the Semionotus elegans group from the Newark Supergroup of eastern North America. Our description is based largely on specimens from the Boonton Formation (Early Jurassic) of New Jersey because they are particularly well-preserved and include good material of both the dermal skeleton and the endoskeleton. A single anamestic suborbital distinguishes Semionotus from its sister-genus Lepidotes. We restrict the Semionotidae, defined by the presence of dorsal ridge scales between the nape and dorsal fin as well as a large posteriorly directed process on the epiotic, to two genera, Semionotus and Lepidotes. We restrict the Semionotiformes, defined by four characters and five character losses, to the Lepisosteidae, Macrosemiidae, and Semionotidae. Our study of Semionotus and previous work on Watsonulus suggest new interpretations of characters and character polarities. These data support the hypothesis that the Semionotiformes as we define them are more closely related to teleosts than either is to Amia. Analysis of the same data using PAUP suggests an equally parsimonious hypothesis that the Semionotiformes and Amia form a monophyletic group that, in turn, forms the sister-group to teleosts.
A species of semionotiform fish, Lepidotes pankowskii sp. nov. is described from the Cenomanian Kem Kem Beds of south-eastern Morocco, based on two three-dimensionally well-preserved partial heads. The new species is distinguished by the presence of suborbitals lying anterior to the orbit. It is most closely similar to other late Mesozoic tritoral species of Lepidotes.
We report on a new semionotiform taxon, Scheenstia zappi gen. et sp. nov., from Schamhaupten in the Late Jurassic limestones of the Franconian and Swabian Alb, southern Germany. Although the taxon is so far represented by a single specimen, excellent preservation allows a detailed description of its skeletal anatomy. Scheenstia zappi is distinguished by the presence of a sensory canal in the supraorbital bones and a saddle-like articular surface in the quadratojugal, both features so far unknown in other semionotiforms. The new taxon is further diagnosed by a unique combination of characters: more than three pairs of extrascapular bones; frontals less than three times longer than their maximal width; semitritorial dentition; four anterior infraorbitals; middle pit line contained in a groove in the dermopterotic and parietal; concave posterior border of the angular, robust bugle-like process of the posttemporal bone; large basal fulcra; eleven fin rays in the lower lobe of the caudal fin (below the lateral line); and a first, scale-like caudal fin ray reduced. Among semionotiforms it most closely resembles Lepidotes, in particular the large tritorial forms of the Late Jurassic and Early Cretaceous of Europe, such as L. mantelli, L. maximus and L. laevis. The peculiar shape of the quadratojugal in Scheenstia zappi resembles the condition in some basal teleosts in which a ventral articular surface of the quadrate probably served in the rotation of the lower jaw.
An acid prepared specimen of Araripelepidotes temnurus (Agassiz, 1841) (Actinopterygii, Semionotiformes) shows the maxilla, dentary, and antorbital. These bones, which were previously only poorly known in this fossil actinopterygian, are described in detail. From the development of a mobile maxilla and the presence of an interoperculum, it is concluded that A. temnurus was a suction feeder. By analogy to the Recent Cyprinus, the diet of A. temnurus probably consisted mainly of small invertebrates.
A revision of the semionotids from the Lower Cretaceous Lagarcito Formation of Argentina leads to the conclusion that only one taxon, Neosemionotus puntanus Bocchino, 1973, is represented, instead of two monospecific genera and one species of Lepidotes as originally thought. Neosemionotus shares with Lepidotes the presence of more than one suborbital arranged in one row and a long posteroventral process of the dentary, features that have previously been thought to be diagnostic of Lepidotes. On the other hand, it shares with Semionotus the presence of conspicuous dorsal ridge scales. However, Neosemionotus is unique in the characteristics of its dorsal and anal fins, which are both flanked only by high and strong paired basal fulcra. These fulcra become gradually higher/deeper posteriorly, reaching approximately the height/depth of the first fin ray. Other probable synapomorphies of Neosemionotus are the presence of a long parietal pit line, a small, approximately triangular interoperculum, the complete absence of fringing fulcra on the dorsal, and anal fins, and the presence of only very few long and slender fringing fulcra on the pelvic and caudal fins. The systematic position of Neosemionotus is still unknown, but the presence of probably primitive features like the high number of extrascapulars, short parietals, the arrangement of suborbitals, and short snout indicate a relatively basal position among semionotids.
The late Late Jurassic fishes collected by the Tendaguru expeditions (1909–1913) are represented only by a shark tooth and various specimens of the neopterygian Lepidotes. The Lepidotes is a new species characterized by a combination of features such as the presence of scattered tubercles in cranial bones of adults, smooth ganoid scales, two suborbital bones, one row of infraorbital bones, non-tritoral teeth, hyomandibula with an anteriorly expanded membranous outgrowth, two extrascapular bones, two postcleithra, and the absence of fringing fulcra on all fins.
Die spätoberjurassischen Fische, die die Tendaguru-Expedition zwischen 1909 und 1913 gesammelt hat, sind durch einen Haizahn und mehrere Exemplare des Neopterygiers Lepidotes repräsentiert. Eine neue Art der Gattung Lepidotes ist beschrieben, sie ist durch eine Kombination von Merkmalen (vereinzelte Tuberkel auf den Schädelknochen adulter Tiere, glatte Ganoidschuppen, zwei Suborbitalia, eine Reihe von Infraorbitalia, nichttritoriale Zähne, Hyomandibulare mit einer membranösen nach vorne gerichteten Verbreiterung, zwei Extrascapularia, zwei Postcleithra und ohne sich gabelnde Fulkren auf dem Vorderrand der Flossen) gekennzeichnet.
In this paper, the sedimentology, petrography and biostratigraphy of the Nam Phong Formation and the overlying Mesozoic Khorat Group in NE Thailand are described. Data were gathered during extensive studies in the field (about 100 outcrop localities were investigated) and from laboratory analyses of over 500 surface samples.
The Nam Phong Formation is dated accurately for the first time as late Norian to Rhaetian, while the Phra Wihan, Sao Khua, Phu Phan and Khok Kruat Formations (of the Khorat Group) are reassigned to the Early Cretaceous (Berriasian to Aptian) on the basis of new palynological data. The age of the intervening Phu Kradung Formation, which is conventionally assigned to the Lower Jurassic, is probably Late Jurassic or Early Cretaceous, although this cannot be determined with confidence. Changes in provenance between the Nam Phong Formation and the overlying Phu Kradung Formation suggest a possible sedimentary hiatus. Palaeocurrent data suggest that sediments were mainly sourced from the north and east.
Part 1 of this paper describes the sedimentology and biostratigraphy of these units; Part 2, which is scheduled to appear in the April, 1996 issue of this Journal, reports on their diagenesis and reservoir quality.
We describe a new semionotiform fish, Tlayuamichin itztli gen. et sp. nov. from the Early Cretaceous (Albian) of Mexico, which constitutes one of the youngest semionotid articulated remains. The new taxon is represented by five well-preserved specimens from the Tlayúa Quarry near Tepexi de Rodríguez in Puebla State, central Mexico. A series of paraethmoid bones anterior to the supraorbital series, supraorbital bones extending beyond the anterior rim of the orbit, the presence of a large pentagonal supraorbital closing the anterior rim of the orbit, seven anterior infraorbitals, dorsally expanded infraor-bitals at the ventral border of the orbit, and the most dorsal suborbital separating the preoperculum from the dermopterotic are potential autapomorphic features of the new taxon. The very long frontals, a dermopterotic that does not contact the anterodorsal corner of the operculum and the presence of a modified pectoral scale are additional features that help to di-agnose the taxon. Tlayuamichin itztli gen. et sp. nov. resembles most closely "Lepidotes" minor from the Middle Purbeck Beds (early Berriasian), England. These two taxa share similarity with other species of Semionotus from the Early Jurassic of North America and the Triassic of Europe, suggesting interesting biogeographic relationships.
Semionotus bergeri
Agassiz, 1833, from the Upper Triassic (Carnian) of southern Germany, the type species ofSemionotus, is here described in detail for the first time, including so far unstudied material in the Naturkunde-Museum Coburg, which allows a fairly complète reconstruction of this fish. The species is diagnosed by the présence of long frontals, about 4 times longer than wide, with antorbital lateral processes, 6–7 posterior infraorbitals, infraorbital at the posteroventral corner of the orbit notably larger than adjacent ones, infraorbitals at the posterior border of the orbit being as deep as long, and the middle élément anteroventrally expanded, dorsal fin base about two times the anal fin base.S. elegans from the Late Triassic-Early Jurassic of the Newark Supergroup in North America, is so far the best know species ofSemionotus and is the only species of this genus that has been included in phylogentic analyses. However, the comparison ofS. bergeri with other proposed speciesof Semionotus, such asS. elegans, and other semionotids casts doubt on the monophyly of this genus as currently understood, since these species exhibit a mosaic distribution of characters.
Fossil wood from the poorly dated (Jurassic-Cretaceous?) continental sediments of the Khorat Group, northeastern Thailand (Isan) is described. The Khorat Group is widely distributed (Laos, Cambodia and Thailand) and, despite its poorly known age, stratigraphy and palaeoecology, is of importance in understanding the Sibumasu-Indochina collision. The systematics of wood assemblage and palaeobiogeographical analysis reveal strong relationships with Indochina, especially Vietnam, and suggest an age in the range Middle Jurassic to Early Cretaceous. According to wood taphonomy, the corresponding trees grew alongside streams under a rather and climate, although this became wetter during the deposition of the upper formations of the Khorat Group.
Abstract Arratia, G. 2009. Identifying patterns of diversity of the actinopterygian fulcra. —Acta Zoologica (Stockholm) 90 (Suppl. 1): 220–235 Fin rays, scutes or ridge scales, and fulcra have been traditionally interpreted as modified scales, but their diversity has been almost ignored. Based on results presented here, revised definitions of these elements are provided. At least two patterns of basal fulcra are found in actinopterygians: in Pattern I all or most basal fulcra are paired elements, whereas in Pattern II, a series of unpaired basal fulcra that are bifurcated proximally, and whose forking gradually becomes larger caudad, are followed by a series of paired elements. Basal fulcra are commonly present on unpaired fins of lower actinopterygians, including basal neopterygians. Among living fish they are absent in polypteriforms, Amia and teleosts. Fringing fulcra are always paired. Three patterns of fringing fulcra series are described: the series of fringing fulcra in basal actinopterygians is formed by expanded terminal segments of marginal lepidotrichia (Pattern A). Another series is formed by a combination of slightly expanded or modified terminal segments of rays and independent spiny, small elements (Pattern B). The third series is formed of small, spiny ossified elements positioned along the leading marginal fin ray(s) (Pattern C). Other patterns of basal and fringing fulcra remain to be investigated, along with their phylogenetic implications.
A new troglobitic species, Nesticus baeticussp. n. (♂♀), inhabiting the karst landscapes of the high part of the Cazorla, Segura and Las Villas Natural Park (NE Jaén, Spain) where it has been found in 8 caves is diagnosed and described, its distribution and habitat are also analyzed.The new species belongs to the Iberian species group that includes Nesticus luquei, Nesticus lusitanicus and Nesticus murgis. Evolutionary relationships of the Iberian Nesticus species are discussed on the basis of morphological and molecular data (cox1 and rrnL).
An acid prepared specimen of Araripelepidotes temnurus (Agassiz, 1841) (Actinopterygii, Semionotiformes) shows the maxilla, dentary, and antorbital. These bones, which were previously only poorly known in this fossil actinopterygian, are described in detail. From the development of a mobile maxilla and the presence of an interoperculum, it is concluded that A. temnurus was a suction feeder. By analogy to the Recent Cyprinus, the diet of A. temnurus probably consisted mainly of small invertebrates.
Two new Lepidotes Agassiz, 1832 species are described from the Early Cretaceous (Barremian) lacustrine beds from Las Hoyas (Cuenca Province, Spain). Lepidotes microrhis n. sp. and Lepidotes tanyrhis n. sp. are represented by articulated specimens. They are defined by the coexistence of characters either unknown in Lepidotes (infraorbitals at the posteroventral corner of the orbit posteriorly extended, reaching the preoperculum only in L. microrhis n. sp.), exceptional (extrascapular commissure passing through the parietal, two suborbitals, edentulous maxillary) or variously distributed (lack of tritoral teeth, unpaired vomer). Lepidotes is frequent at Las Hoyas. It differs from the rare specimens described at Montsec (Province of Lérida, Spain), a usually Berriasian-Valanginian locality that presents numerous elements in common with Las Hoyas. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.
A new locality, called Phu Nam Jun (the "hill of the spring"), is reported from Phu Kradung Formation, northeastern Thailand. According to age constraints provided by the overlying formations, the Phu Kradung Formation may be regarded as either Late Jurassic or basal Cretaceous in age. Systematic excavations conducted in spring 2002 and winter 2003 by the Department of Mineral Resources of Thailand, in collaboration with the Palaeontological Research Centre of Mahasarakham University, the French CNRS and the Musée des Dinosaures d'Espéraza, yielded more than one hundred and twenty fish specimens. All but two specimens belong to Lepidotes buddhabutrensis. One specimen is a semionotid-like fish and one is a skull roof with associated jaws of a lungfish. According to preliminary observations on 1) the spatial distribution of specimens, 2) the mode of preservation of carcasses, 3) the location of the lungfish and 4) the general composition of the fauna, it is suggested that the carcasses dried out prior to fossilisation.
— We studied sequence variation in 16S rDNA in 204 individuals from 37 populations of the land snail Candidula unifasciata (Poiret 1801) across the core species range in France, Switzerland, and Germany. Phylogeographic, nested clade, and coalescence analyses were used to elucidate the species evolutionary history. The study revealed the presence of two major evolutionary lineages that evolved in separate refuges in southeast France as result of previous fragmentation during the Pleistocene. Applying a recent extension of the nested clade analysis (Templeton 2001), we inferred that range expansions along river valleys in independent corridors to the north led eventually to a secondary contact zone of the major clades around the Geneva Basin. There is evidence supporting the idea that the formation of the secondary contact zone and the colonization of Germany might be postglacial events. The phylogeographic history inferred for C. unifasciata differs from general biogeographic patterns of postglacial colonization previously identified for other taxa, and it might represent a common model for species with restricted dispersal.
A new semionotid fish, Lepidotes buddhabutrensis n. sp., is described from the continental Late Jurassic–Early Cretaceous Phu Kradung Formation, Phu Nam Jun, Kalasin Province. L. buddhabutrensis is characterized notably by the pattern of its cheek bones, by its short preorbital region, and by its numerous and well-developed premaxillary teeth. L. buddhabutrensis is provisionally placed in the genus Lepidotes; it shares, however, derived characters with other semionotids, such as Araripelepidotes and Pliodetes. To cite this article: L. Cavin et al., C. R. Palevol 2 (2003).RésuméUn nouveau Semionotidae (Actinopterygii, Neopterygii) du Jurassique terminal–Crétacé basal de Thaïlande. Un nouveau sémionotidé, Lepidotes buddhabutrensis n. sp., est décrit en provenance du Jurassique terminal–Crétacé basal de la formation continentale de Phu Kradung à Phu Nam Jun, province de Kalasin. L. buddhabutrensis se caractérise notamment par la disposition des os de la joue, par une région pré-orbitaire réduite, par de nombreuses dents prémaxillaires bien développées. L. buddhabutrensis est provisoirement placé dans le genre Lepidotes, bien qu’il présente des caractères dérivés d’autres sémionotidés tels qu’Araripelepidotes et Pliodetes. Pour citer cet article : L. Cavin et al., C. R. Palevol 2 (2003).
New geological data are presented and previously published information is reviewed to demonstrate that much of the Khorat Group (Phu Kradung to Khok Kruat Formations) of NE Thailand is Early Cretaceous in age. It is suggested that the Mesozoic red bed sequences of neighbouring Indochina are likely to be of similar age rather than spanning the entire Late Triassic to Early Cretaceous as previously assumed. Moreover, the Lower Nam Phong Formation dated as Late Triassic and previously included as the basal formation of the Khorat Group is now removed from this group, thus creating a hiatus within the Jurassic. There is therefore no clear relationship between the Indosinian Orogeny and the Triassic collision of the Sibumasu (also referred to as Shan-Thai) and Indochina Blocks and the subsequent deposition of the Khorat Group in a Late Triassic-Early Cretaceous thermal sag basin. It is now proposed that much of the sequence was deposited during the Late Jurassic-Early Cretaceous. Jurassic sediments may be absent across much of the Khorat Plateau whereas marine Jurassic sediments to the west and east show no sediments younger than Bajocian. Because sea levels were generally rising in the Middle and Late Jurassic it is likely that the Khorat region was uplifted at this time. It is suggested that the Khorat Group was originally deposited in a foreland basin setting rather than a thermal sag basin following Late Triassic rifting. Moreover, the original site of deposition was to the north in southern China, with the present-day location being the result of movement along the Red River Fault coupled with a clockwise rotation of the Indochina Block (on which the Khorat Group sits) with respect to the South China Block.
This first overview of the bony fish record from the Jurassic and Cretaceous continental deposits of Thailand reveals a significant diversity, with 16 taxa in four formations (the Khlong Min, Phu Kradung, Sao Khua and Khok Kruat Fms). Four of these taxa have already been diagnosed and described, and a couple of others are sufficiently well preserved to be diagnosed in the future. The other taxa are represented at present by fragmentary and isolated remains. The highest diversity is observed among 'semionotids', which occur in the four formations. Sinamiids are represented by at least three taxa that occur only in the Sao Khua and the Khok Kruat Formations. Pycnodont fishes are known by rare and isolated dentitions and teeth in the Khlong Min and Sao Khua Formations, and lungfishes referred to Ferganoceratodus occur in the Khlong Min and the Phu Kradung Formations. The assemblages provide few palaeogeographical indications at present, except for evidence of relationships with China and Central Asia. However, it is expected than once the phylogenetic relationships of these taxa are resolved, we will be able to reconstruct precise palaeogeographical scenarios.
A new semionotiform fish, Isanichthys palustris gen. et sp. nov., is described from the Late Jurassic – Early Cretaceous Phu Kradung Formation, north-east Thailand. I. palustris is known from a single, nearly complete specimen found alongside abundant Lepidotes specimens at the Phu Nam Jun locality. I. palustris shows a mixture of semionotid-like characters, such as the pattern of cheek ossifications, and lepisosteid-like characters, such as the body shape and a dorsal fin opposed by an anal fin. I. palustris possesses only some of the characters currently used to define the Semionotidae. Cladistic analyses including various semionotid and gar taxa, together with Amia calva and Leptolepis coryphaenoides, suggest that the Semionotiformes (Lepisosteidae and ‘Semionotidae’) form a monophyletic clade, but the ‘Semionotidae’ taxa form an unresolved polytomy. The relationships between Semionotiformes, Halecomorphi and Teleostei are unresolved. When restricted to the best-known taxa, however, the analysis shows the monophyly of the Semionotidae sensu stricto (Semionotus + Lepidotes) and a sister-group relationship between halecomorphs and teleosts. These last two results are regarded as the preferred hypothesis for further studies. I. palustris is the only known example of a predaceous, probably piscivorous, ‘semionotid’. It illustrates the great diversity and ecological adaptation of the semionotiforms during the Late Jurassic – Early Cretaceous. We question the phylogenetic relationships of ‘ancient fishes’ founded on molecular-based trees because we suspect that the use of very few Recent taxa as representatives of previously diverse lineages is an inevitable, but important, bias in the construction of such trees.
We describe a new species of lungfish, Ferganoceratodus martini sp. nov., based on a single specimen discovered in the Late Jurassic – Early Cretaceous of the Phu Nam Jun locality, north-eastern Thailand. The material comprises an almost complete skull roof with associated upper and lower jaws, as well as some postcranial remains. F. martini shows characters unexpected and/or unknown in other Mesozoic lungfishes, such as pieces of a ‘hard snout’. The microstructure of the ‘hard snout’ provides support to the Bemis and Northcutt interpretation of the cosmine tissue of Palaeozoic lungfishes as homologous to the complex cutaneous vasculature of the living Neoceratodus. Because the homologies of the ossifications of the skull roof among lungfishes and among piscian sarcopterygians are unsatisfactorily understood, we use a topological nomenclature in the description of the specimen and in the discussion of post-Devonian dipnoan skull roof characters. We define a few characters for the cladistic analysis only, but these are regarded as less theory-laden. We propose a hypothesis of phylogenetic relationships for most of the post-Devonian forms known by skull remains. The main feature is the ancient dichotomy between the Neoceratodus lineage and most of the other Mesozoic forms, including the Lepidosirenids. The palaeobiogeographical pattern shows a series of vicariant events between Laurasia and Gondwana in the Late Triassic – Early Jurassic, followed by a vicariant event between Africa and South America. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 149, 141–177.
The semionotid Lepidotes piauhyensis Roxo and Löfgren, 1936, is redescribed on the basis of original and new material obtained from the Pastos Bons Formation, ?Upper Jurassic–Lower Cretaceous of the Parnaíba Basin, in northeastern Brazil. The species is a hump-backed semionotid reaching about 480 mm standard length. It exhibits, among other characters: dermal bones of the skull roof and circumorbital series densely ornamented with tubercles, suborbitals disposed in a single row, moderately developed crushing dentition, a bony lamina on the ventral portion of the anterior ceratohyal, a complete dorsal scale row, and smooth ganoid scales of lepisosteoid type. The analysis of well preserved specimens allows the description of anatomical structures previously unknown for the species, particularly of the hyoid arch and suspensorium. Some of these structures are comparable to those of the Jurassic species Lepidotes gloriae Thies, 1989 (Cuba), Lepidotes elvensis (Blainville, 1818) (Europe), and Lepidotes lennieri Sauvage, 1893 (Europe).
Gars (Lepisosteidae) are ray-finned fishes with controversial relationships to other actinopterygian lineages. When fossil taxa are considered, gars are grouped with Mesozoic macrosemiids and 'semionotids' in the Semionotiformes, but the intra-relationships within this order are still elusive. Here, the evolutionary history of gars is reinvestigated using a set of well-preserved extinct semionotiform taxa in a phylogenetic analysis. Results indicate that the gar lineage roots in a clade of Late Jurassic-Cretaceous semionotiform fishes. The closest relatives to gars were plant-eating and detritivorous freshwater fishes. The occurrence of semionotiform remains in Early and early Late Cretaceous continental deposits worldwide possibly reflects an important radiation of this group, comparable to the present-day diversification of cypriniforms. Other Late Triassic to Early Cretaceous semionotiform taxa are gathered in a single clade with weakly supported internal nodes, pointing out the necessity to better understand the osteology of these fishes.