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Abstract

A giant caseid, Alierasaurus ronchii, gen. et sp. nov., is herein described, based on a partial postcranial skeleton collected from the Permian Cala del Vino Formation (Alghero, Nurra, northwest Sardinia). Despite the highly conservative morphology of ribs and vertebral material, typical of caseids, the very well-preserved foot elements show highly autapomorphic features, warranting assignment of the specimen to a new genus. In particular, the fourth metatarsal is not short and massive, as in other large caseids, and shows a distinct axial region. Finally, the claw-shaped ungual phalanges are autapomorphic in being proportionately very short, with a strong double ventral flexor tubercle positioned very close to the proximal phalangeal rim, and a distal end that is not spatulate, but rather subtriangular in transverse section. Principal component and reduced major axis slope analyses, performed on 10 caseid specimens, suggest that the observed changes in overall shape of metatarsal IV were mainly linked to the enormous body size reached by the Sardinian specimen.

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... Overall, about eighty bones were recovered, both complete and fragmentary, all referable to the post-cranial skeleton of a very huge animal (Fig. 2). The preparation and study of the material allowed the description and formalization of a new taxon of the Family Caseidae, Alierasaurus ronchii (Romano and Nicosia, 2014) from 'Aliera' or 'Alighera', the old traditional name of the city of Alghero in Sardinia, and Ronchi in honor of Prof. Ausonio Ronchi from Pavia who reported us the new discovery. ...
... Ronchi et al. (2011 also discuss the stratigraphic occurrence of both North American and European caseids; using the North American Land Vertebrate faunochrons proposed by Lucas (2006), the authors suggest a late Kungurian-Roadian age for the upper part of the Cala del Vino Formation, and discuss the implication for the litostratigraphic correlation with the Permian-Triassic succession outcropping in Provence. Romano and Nicosia (2014) provide the first detailed description of the new material with the formalization of the new caseid Alierasaurus ronchii. The author stress how great part of the preserved post-cranial material, especially conformation in ribs and foot elements are fully compatible with the known anatomy of large north American caseids, in particular with that characterizing the genus Cotylorhynchus. ...
... However, Alierasaurus shows apomorphic character, especially in the autopodial elements, supporting the erection of a new genus and species of Caseidae. Romano and Nicosia (2014) discuss the huge size of the new taxon comparable only to the giant North American species Cotylorhynchus hancocki, more than six meters in total length. The author in addition stress how the conformation of preserved large ribs allow to infer a very large "barrel-shaped" rib cage, indicating an high-fibers herbivorous diet (see Hotton et al., 1997;Sues and Reisz, 1998). ...
... Furthermore, based on the topology provided by Maddin et al. (2008), Reisz et al. (2011) moved 'Casea' rutena to the new genus Euromycter, with the new combination E. rutenus. Ronchi et al. (2011) and Romano and Nicosia (2014) described the first skeletal material referable to non-therapsid synapsid from Italy, the caseid Alierasaurus ronchii from the Permian Cala del Vino Formation (Alghero, Nurra, northwest Sardinia). The taxon is known on the basis of partial but diagnostic postcranial material, including vertebrae, ribs, and peculiar autopod elements. ...
... Bones size and preservation, as well as the absence of double and repeated elements, allows us to refer with confidence all new material to the same individual of Alierasaurus ronchii. As already discussed in Ronchi et al. (2011) and Romano and Nicosia (2014) the preserved bone are frequently characterized by several tubercles, scattered on the surface. To understand whether these tubercles are made of bone or simply represent metallic incrustations, a phalanx and rib portion with tubercles were analyzed at CT-Scan, in the facilities of the Museum für Naturkunde in Berlin. ...
... Subclass SYNAPSIDA Osborn, 1903Suborder CASEASAURIA Williston, 1912 Family CASEIDAE Williston, 1911 Genus ALIERASAURUS Romano and Type species. Alierasaurus ronchii Romano and Nicosia, 2014 Alierasaurus ronchii Romano ...
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New characters of the giant caseid Alierasaurus ronchii are described here based on material recovered from the type locality in the Permian deposits of Cala del Vino Formation (Sardinia NW) and additional preparation of the previously collected material. All new described osteological elements are characterized by the same state of preservation and, given the absence of double elements and the total compatibility in absolute size, the new material can be attributed without doubt to the holotypic individual of A. ronchii. Highly diagnostic material includes a caudal neural spine with a broad bifid distal termination. This represents a synapomorphy characterizing the more derived caseids, thus fully confirming the attribution of the Sardinian specimen to Caseidae. Also the other vertebral material and newly collected ribs show a typical caseid structure, fully consistent with the previously published material. Despite the highly partial nature of Alierasaurus, the taxon was included in a recent phylogenetic analysis of caseids to investigate its phylogenetic position within the monophyletic Caseasauria. Alierasaurus falls as the sister taxon of Cotylorhynchus, and is autapomorphic in the general construction of MT-IV and proximal phalanx IV-I. The absolute size of the newly recovered material confirms a gigantic body size for Alierasaurus, comparable, if not greater, to that of the huge North American species Cotylorhynchus hancocki (up to 6 m in length). Such gigantic adult body size, closely correlated to its herbivorous lifestyle, must have been selected during evolution of caseids, leading to substantial advantages in terms of fitness.
... These fossils were collected in Permian fluvial deposits of the Cala del Vino Formation, exposed near Torre del Porticciolo, at the north-western corner of the island. In previous work, these fossils were ascribed to the new genus and species Alierasaurus ronchii, referable to the family Caseidae (Romano & Nicosia, 2014), a long-lived group of herbivorous "pelycosaurs" primarily known from North America, but with a few European records as well (Brocklehurst, Romano, & Fröbisch, 2016;Reisz et al., 2011;Romano, 2017;Romano, Brocklehurst, & Fröbisch, 2017;Romano & Nicosia, 2015;Sigogneau-Russell & Russell, 1974). ...
... The vertebrate remains that are the subject of this study were found in the Cala del Vino Fm. (Cassinis et al., 2003) in the Torre del Porticciolo locality. The chronostratigraphic position of this rock unit was not well established until the discovery of the caseid Alierasurus ronchii (Romano & Nicosia, 2014;Romano, Ronchi, et al., 2017;Ronchi et al., 2011), which established attribution of the unit to the latest Kungurian-Roadian. ...
... Thus, the new specimen from Torre del Porticciolo would represent the ninth report of a sphenacodontid from Europe, throwing new light on the diversity of this faunivorous clade of non-therapsid synapsids on the continent. In addition, with a late early Permian to early middle Permian age for the Cala del Vino Formation (see Romano & Nicosia, 2014; late Kungurian-Roadian in Ronchi et al., 2011), the specimen would represent, to date, the youngest occurrence of sphenacodontids in Europe. ...
Article
The Torre del Porticciolo fossil locality is notable for producing the first osteological material of a basal (i.e., non‐mammalian) synapsid in Italy, the giant herbivore Alierasaurus ronchii, which although known from fragmentary remains, likely represents the largest known late early to early middle Permian synapsid (6–7 m total length). Recently, a new productive site was discovered about 100 m from the Alierasaurus type locality, but roughly at the same stratigraphic level. The fragmentary nature of most of the recovered bones prompted a taphonomical analysis in order to define the type of find, the kind of burial, and the mode of preservation. The vertebrate remains allowed us to infer a complex taphonomical process involving a multiphase entombment. The recovered bones were subjected to both re‐exhumation and reworking. The last short and violent transportation phase before final entombment occurred as a high‐energy flow, probably caused by a river flood that carried sediment and bones together to be emplaced in a semi‐perennial pond in a crevasse splay deposit. Preliminary analysis of recovered material indicates the presence of a large carnivorous basal synapsid referable to the family Sphenacodontidae. This discovery represents the first carnivorous non‐therapsid synapsid from the Permian of Italy and one of only very few known from Europe.
... During the course of their evolution, they passed from very small faunivorous to herbivorous organisms of extremely large size, among the largest reached by terrestrial vertebrates throughout the Palaeozoic. In particular, in a series of recent papers new material and taxa have been described; cladistic analyses were conducted to understand the phylogenetic relationships within Caseasauria (the clade containing Caseidae and Eothyrididae), and also within the broader topic of basal synapsids; specific morphometric studies have been carried out to understand the evolution of specific traits of these basal synapsids (Reisz 2005;Maddin et al. 2008;Reisz et al. 2011;Ronchi et al. 2011;Benson 2012;LeBlanc & Reisz 2014;Reisz & Fr€ obisch 2014;Romano & Nicosia 2014Sumida et al. 2014;Brocklehurst et al. 2016a, b;Spindler et al. 2016;Romano 2017). ...
... The centra are amphicoelous, slightly taller than long in this area, and they do not have thick and rounded lips as observed in other caseids (e.g. Alierasaurus, Romano & Nicosia 2014), ending with a rather sharp and cutting edge. The diagenetic compression does not make it easy to reconstruct the exact outline of the centrum in anterior and posterior view; however, it seems to be roughly subcircular with the dorsal half slightly more expanded transversely than the ventral one. ...
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The postcranial material referable to the Russian caseid Ennatosaurus tecton from the middle Permian is described. Although the cranium has been recently restudied in detail, the descriptions currently available for the postcranial skeleton are essentially limited to the original short account on the holotype provided by Efremov in 1956. The postcranium of Ennatosaurus is informative with respect to both taxonomy and phylogeny, with autapomorphic characters present particularly in the vertebral column. In addition to the anatomical description of the elements presented here, eight principal component analyses were conducted to investigate the position of the various osteological elements of Ennatosaurus within caseid morphospace. The inclusion of members of all major groups of ‘pelycosaurs’ and selected outgroup taxa allowed us to make more extensive preliminary inferences regarding postcranial morphospace occupation of these basal synapsids for each individually considered bone. The analysis revealed a major decoupling among the morphospaces of stylopodial and zeugopodial elements, with femora and humeri showing a shared common pattern, and a wider overlap in their respective morphospace. Conversely, the ulnae, radii, tibiae and fibulae show well-separated regions of morphospace in the different clades, indicating their potential importance, not only for functional and biomechanical studies, but also for taxonomic differentiation. Finally, a 3D photogrammetric model of the mounted specimen at the Paleontological Institute in Moscow forms the basis for the first in vivo reconstruction of Ennatosaurus tecton, providing a potentially realistic picture of the Russian caseid in life. © The Trustees of the Natural History Museum, London 2017. All rights reserved.
... Caseidae is the second subclade of Caseasauria (Figs. 5.2 B and 5.6), and it is predominantly composed of distinctively specialized herbivores. The first caseid to appear in the fossil record is the recently described Eocasea martini from the Late Pennsylvanian of Kansas (Reisz and Fröbisch 2014;although see Spindler et al. 2018 for an alternative placement of Eocasea), but the clade is best known from the Cisuralian and Guadalupian (early to early middle Permian) of North America and Europe (e.g., Olson 1968, Reisz 1986, Sigogneau-Russell and Russell 1974, Reisz et al. 2010a, Romano and Nicosia 2014. Footprints and body fossils reported from the Lodève Basin in France and footprints from the Paraná Basin of Brazil have been taken as evidence that caseids survived into the late Permian (Schneider et al. 2006, da Silva et al. 2012. ...
... This clade includes five main subgroups: Varanopidae, Ophiacodontidae, Edaphosauridae, Sphenacodontidae, and Therapsida (including mammals as an extant subclade), as well as several taxa whose relationships are less certain (e.g., the "haptodonts"). Diagnostic characters for Eupelycosauria include an antorbital region of the skull that is deeper than fragmentary Alierasaurus appears to have reached comparable sizes (Ronchi et al. 2011, Romano andNicosia 2014). ...
... With a temporal distribution spanning from the Late Carboniferous (Eocasea martini Late Pennsylvanian of Kansas; Reisz & Fr€ obisch 2014) to the Middle Permian (Ennatosarus tecton from the Late Roadian-Wordian of Russia; Maddin et al. 2008), caseids are among the longest-surviving groups of non-therapsid ('pelycosaurian') synapsids. Of interest is the great diversity of body size reached by the members of this clade during their evolution, with the most basal species, such as the recently described E. martini (Reisz & Fr€ obisch 2014) and Callibrachion gaudryi (Spindler et al. 2016) being little more than 20 cm in length, whereas giant forms, such as Cotylorhynchus hancocki of North America and Alierasaurus ronchii from Italy (Romano & Nicosia 2014), could reach up to 6.5 m in length, and a substantial body weight (more than 500 kg in Co. hancocki; Reisz & Fr€ obisch 2014). ...
... The recently described basal caseid E. martini (Reisz & Fr€ obisch 2014) and recently re-identified caseids or basal caseasaurs C. gaudryi and Datheosaurus macrourus were not included in the analysis, because all known specimens of these taxa represent juvenile individuals in which the tips of long bones may be largely unfinished. Furthermore, the Sardinian caseid A. ronchii (Ronchi et al. 2011;Romano & Nicosia 2014) is not included because no long bones have been recovered from the holotype locality (apart from the distal end of the ulna). In addition to caseids, specimens of the non-caseid 'pelycosaur' genera Varanops, Ophiacodon, Dimetrodon, Sphenacodon and Edaphosaurus (taxa considered in the above-mentioned phylogenetic analysis) are also included in the analysis. ...
... Middle Permian for the URU. This group of synapsids was relatively abundant duringRonchi et al., 2011;Romano and Nicosia, 2014). As a matter of fact, some of them have been poorly dated, especially Euromycter and Ruthenosaurus, from the Rodez Basin (France), whose ages range from the late Early to the early Late Permian(Reisz et al., 2011). ...
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The continental Permian-Triassic transition in southern Europe presents little paleontological evidence of the Permian mass extinction and the subsequent faunal recovery during the early stages of the Triassic. New stratigraphic, sedimentological and paleontological analyses from Middle-Upper Permian to Lower-Middle Triassic deposits of the Catalan Pyrenees (NE Iberian Peninsula) allow to better constrain the Permian-Triassic succession in the Western Tethys basins, and provide new (bio-) chronologic data. For the first time, a large vertebra attributed to a caseid synapsid from the ?Middle Permian is reported from the Iberian Peninsula - one of the few reported from western Europe. Osteological and ichnological records from the Triassic Buntsandstein facies reveal a great tetrapod ichnodiversity, dominated by small to medium archosauromorphs and lepidosauromorphs (Rhynchosauroides cf. schochardti, R. isp. 1 and 2, Prorotodactylus-Rotodactylus, an undetermined Morphotype A and to a lesser degree large archosaurians (chirotheriids), overall suggesting a late Early Triassic-early Middle Triassic age. This is in agreement with recent palynological analyses in the Buntsandstein basal beds that identify different lycopod spores and other bisaccate and taeniate pollen types of late Olenekian age (Early Triassic). The Permian caseid vertebra was found in a playa-lake setting with a low influence of fluvial water channels and related to the distal parts of alluvial fans. In contrast, the Triassic Buntsandstein facies correspond to complex alluvial fan systems, dominated by highenergy channels and crevasse splay deposits, hence a faunal and environmental turnover is observed. The Pyrenean biostratigraphical data show similarities with those of the nearby Western Tethys basins, and can be tentatively correlated with North African and European basins. The Triassic Pyrenean fossil remains might rank among the continental oldest records of the Western Tethys, providing new keys to decipher the Triassic faunal biogeography and recovery.
... The presence of a caseid vertebra in the Catalan Pyrenees (Fig. 2) indicates a minimum age of Middle Permian for the part of the succession where it was found (Fig. 5). This group of synapsids was relatively abundant during this time interval, although few specimens have been so far reported in Europe (e.g., Sigogneau-Russell and Russell, 1974;Wernerburg et al., 2007;Reisz et al., 2011;Ronchi et al., 2011;Romano and Nicosia, 2014). The Pyrenean vertebra is tentatively attributed to cf. ...
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The Permian and Triassic successions of the Catalan Pyrenees provide key information on the stratigraphic and paleontological record of Southern Europe. These deposits are encompassed in a long terrestrial succession ranging from the Late Carboniferous to the Middle Triassic, having been historically studied by different disciplines (e.g., Mey et al., 1968; Nagtegaal, 1969; Hartevelt, 1970; Gisbert, 1981; Speksnijder, 1985; Saura, 2004; Saura and Teixell, 2006; Gretter et al., 2015). Nevertheless, there are few works focused on the paleontological record, especially on vertebrate remains. A detailed revision of the known Permian and Triassic vertebrate record of the Pyrenean Basin was provided by Fortuny et al. (2011). More recently, the Lower Permian has been biostratigraphically constrained by vertebrate footprints (e.g., Mujal et al., in press), and the Permian-Triassic transition was analyzed in detail in Mujal et al. (2016). Concerning this latter work, our international and interdisciplinary team carried out new stratigraphic, sedimentological and paleontological analyses from the Permian Upper Red Unit (URU) and the Triassic Buntsandstein facies of the Catalan Pyrenees. We aimed to constrain the Permian-Triassic succession in the Western Tethys sub-basins providing new (bio-) chronologic data together with a general sedimentological revision of the fossil bearing stratigraphic units.
... It is overlain by weathered volcaniclastic rocks of uncertain origin (Case Satta ignimbrites), and pumiceous tuffs or lava-rich layers. The age of the uppermost part of TSU 2 was long considered to be post-Autunian, but is now constrained to the early Guadalupian by the presence of fossil bones of a large vertebrate Romano and Nicosia, 2014). ...
Article
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The latest Carboniferous to lower Permian volcanism of the southern Variscides in Sardinia developed in a regional continental transpressive and subsequent transtensile tectonic regime. Volcanism produced a wide range of intermediate–silicic magmas including medium- to high-K calc-alkaline andesites, dacites, and rhyolites. A thick late Palaeozoic succession is well exposed in the four most representative Sardinian continental basins (Nurra, Perdasdefogu, Escalaplano, and Seui–Seulo), and contain substantial stratigraphic, geochemical, and geochronological evidence of the area’s complex geological evolution from the latest Carboniferous to the beginning of the Triassic. Based on major and trace element data and LA–ICP–MS U–Pb zircon dating, it is possible to reconstruct the timing of post-Variscan volcanism. This volcanism records active tectonism between the latest Carboniferous and Permian, and post-dates the unroofing and erosion of nappes in this segment of the southern Variscides. In particular, igneous zircon grains from calc-alkaline silicic volcanic rocks yielded ages between 299 ± 1 and 288 ± 3 Ma, thereby constraining the development of continental strike-slip faulting from south (Escalaplano Basin) to north (Nurra Basin). Notably, andesites emplaced in medium-grade metamorphic basement (Mt. Cobingius, Ogliastra) show a cluster of older ages at 332 ± 12 Ma. Despite the large uncertainty, this age constrains the onset of igneous activity in the mid-crust. These new radiometric ages constitute: (1) a consistent dataset for different volcanic events; (2) a precise chronostratigraphic constraint which fits well with the biostratigraphic data and (3) insights into the plate reorganization between Laurussia and Gondwana during the late Palaeozoic evolution of the Variscan chain.
... By the Kungurian, the lineage leading to Dimetrodon grandis had exceeded the largest known edaphosaurid. The increased diversity and abundance of some of the largest terrestrial animals of the early Permian, the caseids, in the latter stages of the Cisuralian (Olson 1954(Olson , 1968Reisz et al. 2011;Brocklehurst et al. 2013;Romano and Nicosia 2014) may provide a reason for the continued increase in body size: the need to expand the possible diet range to include these even larger prey items. The sphenacodontids also evolved a more sophisticated dental apparatus at this time: "true" ziphodonty, where the serrations of the teeth have denticles with a dentine core . ...
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Body size is one of the most important characteristics of an organism, impacting a great variety of ecological characteristics. The influence of diet on body size has received considerable attention, with previous studies suggesting a greater tendency towards increased body size in herbivores than macro-carnivores. The earliest known herbivorous and macro-carnivorous synapsids provide an ideal case study for examining body size evolution in different dietary regimes. Sphenacomorpha contains two lineages: Edaphosauridae (some of the most abundant terrestrial herbivores in the late Carboniferous and early Permian), and Sphenacodontia (the largest and most abundant carnivores of that time). Phylogenetic comparative analyses are used to compare trait evolution in sphenaco-morphs, including a Bayesian method for identifying branches along which phenotypic selection occurred. Two branches show rapid increases in body size in the late Carboniferous. The first occurred in Edaphosauridae, along the branch leading to the herbivorous members. The later shift towards larger size occurred in Sphenacodontia, producing a clade of large carnivores. It is possible that the rapid appearance of large herbivorous synapsids in the Carboniferous provided the selective pressure for carnivores to increase their size. Following these two shifts, rates of evolution in edapho-saurids slowed significantly, but the carnivorous sphenacodontians showed further increases.
... It is overlain by weathered volcaniclastic rocks of uncertain origin (Case Satta ignimbrites), and pumiceous tuffs or lava-rich layers. The age of the uppermost part of TSU 2 was long considered to be post-Autunian, but is now constrained to the early Guadalupian by the presence of fossil bones of a large vertebrate Romano and Nicosia, 2014). ...
... Although there has been substantial debate surrounding the biostratigraphy of the terrestrial faunas across the lowermiddle Permian transition [1,12,14,[19][20][21][22][23], it is now widely accepted that the San Angelo Formation of Texas, the Chickasha Formation of Oklahoma and the faunas of the Kazanian series from Russia (the Golyusherma Subassemblage) are contemporaneous and of Roadian age (but see discussion in the electronic supplementary material text). The Cala del Vino Formation of Sardinia is also included as an equatorial Laurasian locality (see electronic supplementary material text), despite only having produced a single tetrapod species: the caseid Alierasaurus ronchii [24,25]. ...
Article
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The terrestrial vertebrate fauna underwent a substantial change in composition between the lower and middle Permian. The lower Permian fauna was characterized by diverse and abundant amphibians and pelycosaurian-grade synapsids. During the middle Permian, a therapsid-dominated fauna, containing a diverse array of parareptiles and a considerably reduced richness of amphibians, replaced this. However, it is debated whether the transition is a genuine event, accompanied by a mass extinction, or whether it is merely an artefact of the shift in sampling from the palaeoequatorial latitudes to the palaeotemperate latitudes. Here we use an up-to-date biostratigraphy and incorporate recent discoveries to thoroughly review the Permian tetrapod fossil record. We suggest that the faunal transition represents a genuine event; the lower Permian temperate faunas are more similar to lower Permian equatorial faunas than middle Permian temperate faunas. The transition was not consistent across latitudes; the turnover occurred more rapidly in Russia, but was delayed in North America. The argument that the mass extinction is an artefact of a latitudinal biodiversity gradient and a shift in sampling localities is rejected: sampling correction demonstrates an inverse latitudinal biodiversity gradient was prevalent during the Permian, with peak diversity in the temperate latitudes.
... obs.), Ennatosaurus tecton Efremov, 1956from Russia (e.g., Efremov, 1956Ivakhnenko, 1990;Maddin et al., 2008;Romano et al., 2017a/b;RW pers. obs.), Alierasaurus ronchii Romano and Nicosia, 2014 from Italy (Ronchi et al., 2011, Romano andRomano et al., 2017a), and Caseopsis, Angelosaurus spp., and Cotylorhynchus spp. from the USA (e.g., Stovall et al., 1966;Olson and Beerbower, 1953;Olson, 1962Olson, , 1968Olson and Barghusen, 1962;RW + FS pers. ...
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Lalieudorhynchus gandi gen. nov. and sp. nov. is a new caseid synapsid from the Permian of the Lodève Basin, Occitanie, France. This new taxon is represented by a partial but well-preserved postcranial skeleton, and is characterized by the following apomorphies: a transverse section of the sacral and anterior caudal neural spines with a very thin keel-like process anteriorly, a slender dorsal tip of the dorsal and caudal spines, a narrow distal end of the first sacral rib, a fossa on triceps process of metacoracoid, and a very large distal tarsal 1 of same width than the astragalus, with nearly all sides being shallowly concave. The skeleton corresponds to a sub-adult individual that was excavated from the La Lieude Formation dated as Roadian-Capitanian (Guadalupian). A sedimentological and taphonomical analysis of the type locality, together with preliminary osteohistological observations, suggest that this new French caseid was rather aquatic, as already hypothesised for other large forms. A phylogenetic analysis of caseids is performed to test the position of this new taxon and to better understand the evolution of the clade: interestingly, Lalieudorhynchus gandi gen. nov. et sp. nov. is closer to the North American "Cotylorhynchus" hancocki than to the other French caseids Ruthenosaurus and Euromycter from the Artinskian of the geographically closer Rodez Basin. These two last caseids document the Artinskian radiation of the clade, which remained diverse until Olson's extinction. Caseids survived, as Lalieudorhynchus is one of the youngest representatives of the clade, and may have used novel ecological strategies to access their vegetarian food sources.
... Subsequent to , the list of European 'pelycosaurs' can be extended as follows: (1) Datheosaurus and Callibrachion, previously mistaken as basal sphenacodontians, have been recognized as basal Caseasauria or Caseidae ); (2) further renaming or first description of caseids applied to Euromycter and Ruthenosaurus (Reisz et al. 2011a), as well as Alierasaurus (Ronchi et al. 2011;Romano and Nicosia 2014). A large but undescribed caseid is known from the Lopingian of the Lodéve Basin (Schneider et al. 2006;Werneburg et al., in prep.). ...
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A new fossil amniote from the Fossil Forest of Chemnitz (Sakmarian-Artinskian transition, Germany) is described as Ascendonanus nestleri gen. et sp. nov., based on five articulated skeletons with integumentary preservation. The slender animals exhibit a generalistic, lizard-like morphology. However, their synapsid temporal fenestration, ventrally ridged centra and enlarged iliac blades indicate a pelycosaur-grade affiliation. Using a renewed data set for certain early amniotes with a similar typology found Ascendonanus to be a basal varanopid synapsid. This is the first evidence of a varanopid from Saxony and the third from Central Europe, as well as the smallest varanopid at all. Its greatly elongated trunk, enlarged autopodia and strongly curved unguals, along with taphonomical observations, imply an arboreal lifestyle in a dense forest habitat until the whole ecosystem was buried under volcanic deposits. Ascendonanus greatly increases the knowledge on rare basal varanopids; it also reveals a so far unexpected ecotype of early synapsids. Its integumentary structures present the first detailed and soft tissue skin preservation of any Paleozoic synapsid. Further systematic results suggest a varanodontine position for Mycterosaurus, the monophyly of South African varanopids including Anningia and the distinction of a skeletal aggregation previously assigned to Heleosaurus, now renamed as Microvaranops parentis gen. et sp. nov.
... The presence of a caseid vertebra in the Catalan Pyrenees (Fig. 2) indicates a minimum age of Middle Permian for the part of the succession where it was found (Fig. 5). This group of synapsids was relatively abundant during this time interval, although few specimens have been so far reported in Europe (e.g., Sigogneau-Russell and Russell, 1974;Wernerburg et al., 2007;Reisz et al., 2011;Romano and Nicosia, 2014). The Pyrenean vertebra is tentatively attributed to cf. ...
... Noteworthy, this vertebra is stratigraphically above the tetrapod footprints, thus the latter might be older than Wordian. Regarding similar caseid record in nearing basins, large specimens are known from the Permian localities of Sardinia Romano and Nicosia, 2014) and the French La Lieude (Reisz et al., 2011). Additionally, the large footprints of Planipes, ichnogenus from the middle Permian of France (Lodève Basin, Gand et al., 2000;Saint-Raphaël Estérel Basin, Gand et al., 1995) and South Africa (Tapinocephalus assemblage zone, Valentini et al., 2009), are assigned to caseids and/or therapsid trackmakers. ...
... Together, the records provide different representations of the faunal composition and, once integrated, enhance the understanding of the faunal diversity of this area of Pangea during the latest early Permian to early middle Permian time interval. While the skeletal remains indicated medium to large carnivorous basal synapsids presently referred to the family Sphenacodontidae (Romano et al., 2018) and giant herbivorous caseid (i.e., Alierasaurus ronchii, Romano & Nicosia, 2014Romano et al., 2017), the recently discovered ichnosite adds a further constituent of the terrestrial palaeofauna, at least, also a small animal, represented by Merifontichnus footprints, ranging between 4 and 10 cm in length. ...
Article
The Torre del Porticciolo palaeontological locality (Alghero, northwest Sardinia, Italy) is important for having provided the skeletal remains of the first Permian basal synapsid from Italy, Alierasaurus ronchii, the largest late early Permian to early middle Permian non-therapsid synapsid known to date. Recently, other skeletal remains preliminarily attributed to a carnivorous non-therapsid synapsid were described from a second site, approximately from the same stratigraphic level within the Cala del Vino Fm. During the excavation of this second site, tetrapod tracks were found near Cala Viola, about 1 km from the first two sites. The new find represents the first ichnological record from the Permian of Sardinia. The ichnological analysis allowed the recognition of tetrapods presently not recognized, just on the base of skeletal remains. This new evidence sheds more light on the faunal diversity within the Cala del Vino Fm., which is one of the few examples in the Permian of Europe of a combined ichno-and body-fossil record. The tracks have been referred to as Merifontichnus, an ichnotaxon established from the uppermost portion of the Permian succession of the Lodève Basin in southern France. The new material is the first reliable occurrence of this ichnotaxon from Italy and would represent, to date, the oldest occurrence of the ichnogenus.
... As in captorhinids, caseids explore different diets and body sizes. These include forms such as the very small Eocasea martini (Reisz & Fr€ obisch 2014) to the huge North American taxa Cotylorhynchus hancocki and the giant caseid from Italy Alierasaurus ronchii, which was 6-7 m long (see Ronchi et al. 2011;Romano & Nicosia 2014;Romano et al. 2017b) and likely had a bulky torso for high-fibre fermentation. The study indicated that the portion of a long bone most affected by allometric growth is the mid-shaft width of the bone (Romano 2017a). ...
Article
Captorhinids are a speciose clade of sauropsids that are crucial to understand several aspects of basal amniote general biology. Members of the Captorhinidae explored different diets and, amongst basal amniotes, were one of the first groups to demonstrate high-fibre herbivory. Several papers have been published on the cranial anatomy of captorhinids, but there are relatively few studies which focus on the post-cranium, especially on the appendicular skeleton and long bones. This contribution presents the first quantitative long bone scaling in Captorhinidae performed through morphometric analyses. From classical biomechanical research, it is well-established that to accommodate an increase in size, gravity will result in elastic deformation of long bones. This outcome is especially significant in terrestrial tetrapods with a sprawling limb posture such as captorhinids, where great torsional stresses are applied to long bones, both during locomotion and in the resting phase. In this paper, we test whether the consistent evolutionary size increase in captorhinids led to major re-patterning in long bone structure as theoretically expected, based on the theory of elastic similarity. Morpho-metric analysis shows that, apart from a small positive allometry in the humerus, cap-torhinid long bones scale geometrically as body size increases. Thus, the predicted elastic similarity to maintain similar levels in peak stress with an increase in dimensions does not seem not to apply to long bone evolution in captorhinids. We propose that, as already observed experimentally in larger-bodied varanid lizards, large cap-torhinids could also mitigate size-related increases in stress by reducing femur rotation and increasing the percentage of the stride cycle during which the right hindfoot was on the ground (i.e. the duty factor). In this way, large captorhinids could avoid reaching peak stress thresholds by sacrificing speed during locomotion and without a substantial long bone re-patterning or postural change. □ Allometry, duty factor, locomotion, long bone scaling, Palaeozoic. Marco Romano ✉ [marco.romano@uniroma1.it], and Bruce Rubidge [bruce.rubidge@ wits.ac.za], Evolutionary Studies Institute (
... nov. (Romano and Nicosia, 2014), based on a partial postcranial skeleton, seems to support a late Early Permian to early Mid-Permian transitional age. Moreover, this datum probably rests below a pronounced stratigraphic gap, which could be linked at a large scale to the 'Mid-Permian Episode' of Deroin andBonin, 2003 (Cassinis et al., 2012). ...
... Amongst basal synapsids, large body size had already evolved in the 'pelycosaurs' during the late Early Permian and the early Middle Permian, especially amongst the large herbivorous members of the Family Caseidae (Olson 1968;Reisz 1986). The largest were the North American genus Cotylorhynchus (especially C. hanckocky), and the huge Italian Permian caseid from Sardinia Alierasaurus ronchii (Ronchi et al. 2011;Romano and Nicosia 2014;Romano et al. 2017), with an estimated body length of 6.5-7 m. The independent evolution of large body size amongst basal synapsids at different geological periods is linked to a complex combination of physiological and ecological factors. ...
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Dinocephalians were the earliest large terrestrial tetrapods from Gondwana, making this group crucial in understanding body mass (BM) evolution in basal synapsids, but no detailed weight determinations are available for the clade. Here we present the first BM estimate for a dinocephalian on the basis of the remarkably well preserved and complete skeleton of the basal tapinocephalid Tapinocaninus pamelae from the lowermost Beaufort Group of South Africa. We reconstructed three 3D models of Tapinocaninus using mounted skeletons of the dinocephalians Moschops and Ulemosaurus to reconstruct the missing elements. Applying a density range between 0.9 and 1.15 Kg/1000 cm3 for living tissue to the model we reconstructed an average BM of 892.63 Kg for the taxon. Classic regression formulae, based on humerus and femur circumference, provide higher values of 1694.5 Kg and 2015.8 Kg, with an overestimation of 90% and 126% respectively. The study confirms that volumetric BM estimates are more precise, and are recommended if relatively complete skeletons are available. The ‘intermediate’ posture recognized for Tapinocaninus, more upright with respect to the sprawling condition characterizing sphenacodontid ‘pelycosaurs’, could represent a response to a large BM, which, for the first time in synapsids, reaches weights close to a tonne.
... A potentially important site for the faunal correlation of the latest Cisuralian and possibly the base of the Guadalupian is the Torre del Porticciolo locality in NW Sardinia, belonging to the Cala del Vino Formation (Fig. 2). Although this formation lacks independent age control from radioisotopic dates and marine fossils, the occurrence of large caseid Romano and Nicosia, 2014;Romano et al., 2017) and sphenacodont remains is remarkable for the Permian of Western Europe, as is the presence at the same site of tetrapod footprints . The co-existence of these tetrapod remains is consistent with a Redtankian-Littlecrotonian LVF age according to Lucas (2006Lucas ( , 2017Lucas ( , 2018, so a late Kungurian to early Roadian age can be hypothesized. ...
Article
Nonmarine biostratigraphic/biochronologic schemes have been created for all or parts of the late Carboniferous–Middle Triassic using palynomorphs, megafossil plants, conchostracans, blattoid insects, tetrapod footprints and tetrapod body fossils, and these provide varied temporal resolution. Cross correlation of the nonmarine biochronologies to the Standard Global Chronostratigraphic Scale has been achieved in some parts of the late Carboniferous–Middle Triassic in locations where nonmarine and marine strata are intercalated, the nonmarine strata produce biochronologically significant fossils and the marine strata yield fusulinids, conodonts and/or ammonoids. Other cross correlations have been aided by magnetostratigraphy, chemostratigraphy and a growing database of radioisotopic ages. A synthetic nonmarine biochronology for the late Carboniferous–Middle Triassic based on all available nonmarine index fossils, integrated with the Standard Global Chronostratigraphic Scale, is presented here. The focus is on the nonmarine biostratigraphy/biochronology of blattoid insects, conchostracans, branchiosaurid amphibians, tetrapod footprints and tetrapod body fossils within the biochronological framework of land-vertebrate faunachrons. Correlation to the Standard Global Chronostratigraphic Scale presented here is divided into seven time intervals: Pennsylvanian, Carboniferous–Permian boundary, Cisuralian, Guadalupian, Lopingian, Permian–Triassic boundary and Early to Middle Triassic. The insects, conchostracans and branchiosaurs provide robust nonmarine correlations in the Pennsylvanian–Cisuralian, and the footprints and tetrapod body fossils provide robust correlations of varied precision within the entire Pennsylvanian–Middle Triassic. Radioisotopic ages are currently the strongest basis for cross correlation of the nonmarine biostratigraphy/biochronology to the Standard Global Chronostratigraphic Scale, particularly for the Pennsylvanian–Cisuralian. Chemostratigraphy and magnetostratigraphy thus far provide only limited links of nomarine and marine chronologies. Improvements in the nonmarine-marine correlations of late Paleozoic–Triassic Pangea require better alpha taxonomy and stratigraphic precision for the nonmarine fossil record integrated with more reliable radioisotopic ages and more extensive chemostratigraphic and magnetostratigraphic datasets.
... This new evidence sheds more light on the faunal diversity within the late Kungurian?-Roadian "Cala del Vino formation", which is one of the few examples in the Permian of Europe of a combined ichno-and body-fossil record Romano and Nicosia, 2014;Romano et al., 2019. The tracks have been referred by to Merifontichnus, an ichnotaxon established from the uppermost portion of the Permian succession of the Lodève Basin, in southern France (Gand et al., 2000). ...
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The Cisuralian tetrapod ichnoassociation from Italy is long known, in fact it is the first described from the Southern Alps. After some pioneering works in the 19th Century, several new research and discoveries were undertaken starting from the second half of the 20 th Century until now. This ichnoassociation is characterised by abundant and diverse reptile tracks (Dromopus, Erpetopus, Hyloidichnus, Merifontichnus and Varanopus), uncommon anamniote tracks (Amphisauropus, Batrachichnus and Limnopus) and very rare synapsid tracks (cf. Dimetropus). The bulk of discoveries are located in the central Southern Alps, in the Orobic and Collio basins, and in minor part in the Athesian District. These basins include a well-preserved and diverse ichnoassociation that is central to tetrapod footprint biostratigraphy and in the definition of the late Cisuralian reptile radiation inferred from the footprint record, well-calibrated by several recent radiometric dates that constrain the ages of the footprint-bearing units. The new site from NW Sardinia includes few late Kungurian?-Roadian tetrapod footprints, that however deserve great attention because of the possible biostratigraphic implications and the unusual co-occurrence with tetrapod remains.
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Pareiasaurs (Amniota, Parareptilia) were characterized by a global distribution during the Permian period, forming an important component of middle (Capitanian) and late Permian (Lopingian) terrestrial tetrapod biodiversity. This clade includes some of the first large-sized terrestrial herbivores, playing a fundamental role in the structure of middle and late Permian biodiversity and ecosystems. Despite their important ecological role and relative abundance around the world, our general knowledge of the biology of these extinct tetrapods is still quite limited. In this contribution we provide a possible in-vivo reconstruction of the largest individual of the species Scutosaurus karpinskii and a volumetric body mass estimate for the taxon, considering that body size is one of the most important biological aspects of organisms. The body mass of Scutosaurus was calculated using a 3D photogrammetric model of the complete mounted skeleton PIN 2005/1537 from the Sokolki locality, Arkhangelsk Region, Russia, on exhibit at the Borissiak Paleontological Institute, Russian Academy of Sciences (Moscow). By applying three different densities for living tissues of 0.99, 1 and 1.15 Kg/1000 cm3 to the a reconstructed ‘slim’, ‘average’ and ‘fat’ 3D models we obtain an average body mass respectively of 1060, 1160 and 1330 Kg, with a total range varying from a minimum of one ton to a maximum of 1.46 tons. Choosing the average model as the most plausible reconstruction and close to the natural condition, we consider a body mass estimate of 1160 Kg as the most robust value for Scutosaurus, a value compatible with that of a large terrestrial adult black rhino and domestic cow. This contribution demonstrates that barrel-shaped herbivores, subsisting on a high-fibre diet and with a body mass exceeding a ton, had already evolved in the upper Palaeozoic within parareptiles, shedding new light on the structure of the first modern terrestrial ecosystems.
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According to a traditional view, the specific diet in vertebrates is one of the key factors structuring the composition of the gut microbiota. In this interpretation, the microbiota assumes a subordinate position, where the larger host shapes, through evolution and its fitness, the taxonomical composition of the hosted microbiota. The present contribution shows how the evolution of herbivory, framed within the new concept of holobiont, the possibility of inter-kingdom crosstalk and its epigenetic effects, could pave the way to a completely reversed interpretation: instead of being passively shaped, the microbiota can mold and shape the general host body structure to increase its fitness. Central elements to consider in this context are the inter-kingdom crosstalk, the possibility of transporting RNAs through nanovesicles in feces from parents to offspring, and the activation of epigenetic processes passed on vertically from generation to generation. The new hypothesis is that the gut microbiota could play a great role in the macroevolutionary dynamics of herbivorous vertebrates, causing directly through host-microbiota dialogue of epigenetic nature (i.e., methylation, histone acetylation, etc.), major changes in the organisms phenotype. The vertical exchange of the same microbial communities from parents to offspring, the interaction of these microbes with fairly uniform genotypes, and the socially restricted groups where these processes take place, could all explain the reasons why herbivory has appeared several time (and independently) during the evolution of vertebrates. The new interpretation could also represent a key factor in understanding the convergent evolution of analogous body structures in very distant lineages.
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The origin of the diaphragm remains a poorly understood yet crucial step in the evolution of terrestrial vertebrates, as this unique structure serves as the main respiratory motor for mammals. Here, we analyze the paleobiology and the respiratory apparatus of one of the oldest lineages of mammal-like reptiles: the Caseidae. Combining quantitative bone histology and functional morphological and physiological modeling approaches, we deduce a scenario in which an auxiliary ventilatory structure was present in these early synapsids. Crucial to this hypothesis are indications that at least the phylogenetically advanced caseids might not have been primarily terrestrial but rather were bound to a predominantly aquatic life. Such a lifestyle would have resulted in severe constraints on their ventilatory system, which consequently would have had to cope with diving-related problems. Our modeling of breathing parameters revealed that these caseids were capable of only limited costal breathing and, if aquatic, must have employed some auxiliary ventilatory mechanism to quickly meet their oxygen demand upon surfacing. Given caseids' phylogenetic position at the base of Synapsida and under this aquatic scenario, it would be most parsimonious to assume that a homologue of the mammalian diaphragm had already evolved about 50 Ma earlier than previously assumed.
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In a recent study, the phylogeny of Caseidae (a herbivorous family of Palaeozoic synapsids belonging to the paraphyletic grade known as pelycosaurs) was analysed with a dataset employing more than three hundred continuous morphological characters in an effort to follow the principles of total evidence. Continuous characters are a source of great debate, with disagreements surrounding their suitability for and treatment in phylogenetic analysis. A number of shortcomings were identified in the handling of continuous characters in this study of caseids, including the use of gap weighting to discretize the characters and potential issues with redundancy and character non-independence. Therefore , an alternative treatment for these characters is suggested here. First, rather than using gap weighting, the continuous characters were analysed in the program TNT, in which the raw values can be treated as continuous rather than discrete. Second, prior to the phylogenetic analysis, the continuous characters were subjected to a log-ratio principal component analysis, and then the principal components were included in the character matrix rather than the raw ratios. Analysing the original data in TNT produced little difference in the results, but using the principal components as continuous characters resulted in alternative positions for Caseopsis agilis, Ennatosaurus tecton and Caseoides sanangeloensis. The differences are judged to be due to the reduced redundancy of the characters, the smaller number of principal components not overwhelming the discrete characters and the use of a scaling method which allows principal components with a higher variance to have a greater influence on the analysis. The positions of highly fragmentary fossils depended heavily on the method used to treat the missing characters in the principal component analysis, and so the method proposed here is not recommended for analysing very incomplete taxa.
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This study represents a reinvestigation of two historical fossil discoveries, Callibrachion gaudryi (Artinskian of France) and Datheosaurus macrourus (Gzhelian of Poland), that were originally classified as haptodontine-grade sphenacodontians and have been lately treated as nomina dubia. Both taxa are here identified as basal caseasaurs based on their overall proportions as well as dental and osteological characteristics that differentiate them from any other major synapsid subclade. As a result of poor preservation, no distinct autapomorphies can be recognized. However, our detailed investigations of the virtually complete skeletons in the light of recent progress in basal synapsid research allow a novel interpretation of their phylogenetic positions. Datheosaurus might represent an eothyridid or basal caseid. Callibrachion shares some similarities with the more derived North American genus Casea. These new observations on Datheosaurus and Callibrachion provide new insights into the early diversification of caseasaurs, reflecting an evolutionary stage that lacks spatulate teeth and broadened phalanges that are typical for other caseid species. Along with Eocasea, the former ghost lineage to the late Pennsylvanian origin of Caseasauria is further closed. For the first time, the presence of basal caseasaurs in Europe is documented.
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Occupying the role of primary consumer and having an early–middle Permian age range, caseids (Caseasauria, Synapsida) are fundamental to the interpretation of the early history of terrestrial vertebrate ecosystems. Despite this importance, no comprehensive, species-level phylogenetic study of Caseidae has yet been performed. Herein, we present a phylogenetic analysis of the group, using gap weighting to include poorly known taxa. Besides the description and comments on the resultant topologies, some more general issues concerning cladistic methodologies are briefly addressed. This study highlights the importance of a total-evidence approach, including as many within-group taxa and characters as possible. Continuously varying characters, in the form of indices derived from measurement of individual skeletal elements, proved to be highly important, adding significantly to the resolution of, and support for, recovered trees. The utility of the postcranial skeleton in understanding relationships among basal synapsids is highlighted.
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Detailed stratigraphical-sedimentological investigations have recently focused on the Permian to Triassic continental sequences of Nurra (NW Sardinia) and Provence (SE France) with the shedding of new light on the chrono- and lithostratigraphical correlations between these two distant areas today. The target of this research is to reconstruct the paleogeography of this western Mediterranean sector during the Late Palaeozoic-Early Mesozoic transition, and to make inferences on the most reliable palaeoposition of the Corsica- Sardinia block before its drift toward the Tyrrhenian area. The investigated successions are presently and mainly exposed in Sardinia, along the coastal area of Cala Viola-Porto Ferro, up to Punta Lu Caparoni (N of Alghero) and in France, between Sanary and Carqueiranne (W and E of Toulon). Facies and palaeoenvironmental analysis, enhanced by the outstanding quality of outcrops, allowed us to correlate both the successions and, consequently, to highlight three main stratigraphic sequences which are recognisable at a regional scale. The stacking pattern of these sequences is as follow: The first sequence shows reduced thicknesses and lies unconformably on the Variscan metamorphic basement. It is initially represented by a Basal Conglomerate entirely composed of basement lithoclasts and later by alluvial-to-lacustrine deposits, named the Punta Lu Caparoni Fm. in Sardinia and the Les Pellegrins Fm. in Provence. The first «Formation» is rich in Autunian mega- and microfloras, while for the second, new palynological research is in progress. In both areas, volcanic rocks of presumed calc-alkaline affinity are discontinuously associated within and above these sediments. The second sequence is the most represented both in Sardinia and France. It consists of an alluvial megacycle which begins with tens of metres of channelised quartz-conglomerates and arenites, deposited in a braided alluvial setting. These deposits, represented in Nurra by the Pedru Siligu Fm. and in Provence by the Transy Fm., unconformably overlie the first sedimentary and volcanic sequence. Further volcanic activity, ascribed to the Bron Fm. in Provence and identified possibly with that of the Casa Satta volcaniclastics in Nurra, followed the above-mentioned quartz-rich formations. The sequence passes upwards into reddish alluvial sediments with very similar facies (Porto Ferro and Les Salettes Fms). A terminal lacustrine event in the latter unit yielded rich macro- and microflora, which allowed us to relate these deposits to post-Kungurian/pre- Tatarian times. The first episodes of undoubtedly alkaline volcanism (basalts) also occur in the Salettes Fm. The overlying St.-Mandrier and Fabregas Fms in Provence, and the Cala del Vino Fm. in Nurra, are represented again by very thick alluvial, mainly meandering deposits, locally grading, as in the second unit, into playa sediments. Volcanic rocks crop out moderately in both regions. The top of this second, mainly siliciclastic succession probably pertains to undefined Late Permian (Tatarian?) times. The third sequence begins with a thin quartz-conglomerate band, which includes wind-worn clasts testifying to an arid climate, named Poudingues de Port-Issol in Provence and Conglomerato del Porticciolo in Nurra. These basal layers rest unconformably on the previous formations and are followed by over 50 m of medium to fine reddish sandstones and siltstones, laid down in a floodplain by terminal fans, which are known as the Grès de Gonfaron in the former area and the Arenarie di Cala Viola in the latter. The age of this sequence, which reaches up to the Middle Triassic marine Muschelkalk, is generally delimited between the Olenekian and the Anisian. Later, the authors of this paper highlight some preliminary results about the stratigraphic position and petrographic affinity of the Permian volcanics in Nurra, which have been long debated. In particular, a conspicuous mainly ignimbritic body was in places identified between the Punta Lu Caparoni and the Pedru Siligu Fms.; the volcaniclastic products of Casa Satta, more than 20 m thick, appear intercalated between the Pedru Siligu and the Porto Ferro Fms, and thus they pertain to the second sequence; a third and younger volcanic episode, which is represented by some metre-thick tuffs and cinerites cropping out within the Cala del Vino Fm. at the Ponte Crabolu locality, occurs below the Triassic Buntsandstein, though is as yet lacking in a clear stratigraphic position. The serial affinity of the aforementioned volcanics, which appear generally affected by heavy hydrothermal alteration or induced by significant secondary depletion of mobile elements, needs further research. Only the alkaline affinity of the welded tuffs at M. Santa Giusta has been recently confirmed. As a consequence, in order to define appropriately their petrographic and geochemical composition, a comparative study of these Permian volcanics of Nurra with the relatively well known igneous sequences of South- Provence is in progress.
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Abstract - After theoretical analyses on the application of the main straligraphic methods to continental deposits, we carried out a feasibility analysis to assess the ages of Permian and Tri¬assic continental sediments by means of tetrapod footprints. The data mainly originate from the Central and Southern Alps. The paleogeography of the Alpine region during Permian and Triassic times gave rise to a unique geological situation and well-exposed sections in which marine sediments, continental deposits rich in footprints and volcanic rocks are interfingered. The resulting mixed sections enable us to build a framework of biostratigraphical and chronological data in which tetrapod footprint-based evolutionary groups can be considered as biochronological units. Such units (Land Ichnofaunal Units) and the corresponding biochronological units (Land Ichnofaunal Ages), still to be formalized, seems to reveal some advantages, with respect to other dating systems.
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The cranial anatomy of the Early Permian synapsid Varanosaurus is restudied on the basis of previously described specimens from Texas and a recently discovered specimen from Oklahoma. Cladistic analysis of the Eupelycosauria, using a data matrix of 95 characters, provides the following hypothesis of relationships of Varanosaurus: 1) Varanosaurus is a member of the family Ophiacodontidae; 2) of the ophiacodontid genera included in the analysis, Varanosaurus and Ophiacodon share a more recent common ancestor than either does with the more primitive Archaeothyris; and 3) a clade containing the progressively more derived taxa Edaphosauridae, Haptodus, and Sphenacodontoidea (Sphenacodontidae plus Therapsida), together with Varanopseidae and Caseasauria, are progressively more distant outgroups or sister taxa to Ophiacodontidae. A revised diagnosis is given for Varanosaurus. -Authors
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Stream channel infills near Garnett, Kansas preserve the most abundant and diverse assemblage of amniotes known from the Carboniferous. In addition to the diapsid Petrolacosaurus kansensis and the synapsids Haptodus garnettensis, Xyrospondylus ecordi, and Ianthasaurus hardestiorum, at least three additional synapsid taxa can be recognized, including a new eupelycosaur genus that is represented by a partial skull and an isolated maxilla. Ianthodon schultzei n. gen. et sp. possesses three premaxillary and seventeen or eighteen maxillary teeth, and the individual teeth are generally conical in outline with only a slight recurvature near the tip. On the lingual surface, the teeth possess densely packed longitudinal fluting that extends to the tip of each tooth. No distinct caniniform tooth is present on the maxilla, but there is a modest caniniform region along the anterior one-third of the bone. I. schultzei is also characterized by a tall lacrimal, and the pineal foramen is found at the midpoint of the median parietal suture. Available evidence suggests that Ianthodon is a member of Sphenacodontia and is positioned within the "haptodont" grade of synapsids. Phylogenetic evidence and a review of occurrence data from Garnett and the 21 other reported Pennsylvanian amniote-bearing localities indicate that the early history of Amniota is characterized by: 1) a basal dichotomy into synapsids and sauropsids; and 2) an uneven rate of diversification, with synapsids rapidly diversifying and quickly developing a dominant role in the terrestrial ecosystems of the late Paleozoic.
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The origin and early evolution of amniotes (fully terrestrial vertebrates) led to major changes in the structure and hierarchy of terrestrial ecosystems. The first appearance of herbivores played a pivotal role in this transformation. After an early bifurcation into Reptilia and Synapsida (including mammals) 315 Ma, synapsids dominated Paleozoic terrestrial vertebrate communities, with the herbivorous caseids representing the largest vertebrates on land. Eocasea martini gen. et sp. nov., a small carnivorous caseid from the Late Carboniferous, extends significantly the fossil record of Caseidae, and permits the first clade-based study of the origin and initial evolution of herbivory in terrestrial tetrapods. Our results demonstrate for the first time that large caseid herbivores evolved from small, non-herbivorous caseids. This pattern is mirrored by three other clades, documenting multiple, independent, but temporally staggered origins of herbivory and increase in body size among early terrestrial tetrapods, leading to patterns consistent with modern terrestrial ecosystem.
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["Short communication", no abstract. The conclusions follow:] The result of our study that Apsisaurus witteri is a varanopid synapsid, not an eosuchian diapsid, has significant implications to our understanding of both synapsid and diapsid evolution. First, this finding increases the known diversity of varanopid synapsids even further. Even though varanopids are relatively rare members of Lower and Middle Permian assemblages, their fossil record has been expanding steadily in the last three decades both taxonomically and temporally. Varanopids are now known from Carboniferous and Lower Permian rocks in North America and Europe, and from Middle Permian strata of Russia and South Africa. Varanopids range in size from 30 cm to over 200 cm in total body length (Reisz and Laurin, 2004), and they are distinct from other members of their terrestrial vertebrate assemblages in being relatively gracile predators. Conversely, and more significantly, the taxonomic diversity of diapsid reptiles in the Paleozoic has suffered another loss, resulting in an extremely scant fossil record for these reptiles. This is a startling development when considering that diapsids came to dominate theMesozoic era so completely and continue to be taxonomically more diverse than synapsids even today. Although diapsid reptiles first appear in the fossil record in the Pennsylvanian, less than 10 million years after the first appearance of the oldest known reptiles and synapsids, their fossil record is very poor throughout the remainder of the Paleozoic, when amniote evolution experienced its first massive diversification. With the recognition that Apsisaurus is not a diapsid reptile, the Middle Permian Lanthanolania (Modesto and Reisz 2002) from north-central Russia becomes the oldest known neodiapsid (oldest known eosuchian, sensu Laurin, 1991). All other, older diapsid reptiles are members of Araeoscelidia, a clade of small, gracile forms that represent the initial Carboniferous and Early Permian diversification of diapsids (deBraga and Reisz 1995). These diapsids are only known from a handful of localities in North America and Europe. Only in the Late Permian do we see the appearance of other diapsids, the younginiform eosuchians. Future discoveries may alter this perceived pattern of early diapsid evolution, but for now, the picture that emerges is that diapsids were rare during the initial stages of amniote diversification, or that they diversified in habitats that where the fossilization potential was low.
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