Article

A new otter of giant size, Siamogale melilutra sp. nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines

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  • Natural History Museum of Los Angeles
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Abstract

Otters (subfamily Lutrinae) are semi-aquatic predators in the family Mustelidae. Modern otters have a worldwide distribution but their fossil record is poor, often consisting of fragmentary jaws and teeth. Multiple lineages have developed bunodont dentitions with enlargements of molars, usually for cracking molluscs or other hard foods. Some lineages have evolved badger-like teeth and, as a result, were often confused with melines (Old World badger clade). Siamogale thailandica Ginsburg, Invagat, & Tassy, 1983 from the middle Miocene basin of Mae Moh in northern Thailand is one such species, whose fragmentary dental remains have thus far impeded our understanding. A new species of fossil otter, Siamogale melilutra sp. nov., represented by a nearly complete cranium, mandible and partial skeletons of at least three individuals, was recovered from the latest Miocene (∼6.2 Ma) lignite beds of the Shuitangba Site in north-eastern Yunnan Province, south-western China. Computed tomography (CT) restoration of the crushed skull reveals a combination of otter-like and badger-like cranial and dental characteristics. The new species belongs to the Lutrinae because of its possession of a large infraorbital canal and ventral expansion of the mastoid process, among other traits. A distally expanded M1, however, gives a badger-like appearance. In overall morphology the Shuitangba otter is closest to Siamogale thailandica. A previously described jaw (‘Lutra’ aonychoides) from the early Pliocene of the Yushe Basin in north China is also here referred to S. melilutra. No previous attempt has been made to provide a global phylogenetic framework for otters. We present the first combined morphological and molecular (nuclear and mitochondrial DNAs) character matrices of five extant (Pteronura, Lontra, Enhydra, Aonyx, Lutra) and eight extinct genera (Tyrrhenolutra, Paralutra, Paludolutra, Enhydritherium, Siamogale, Vishnuonyx, Sivaonyx, Enhydriodon) to better understand the evolution of bunodont otters. Parsimony and Bayesian analyses consistently recover an eastern Asian clade that includes forms from Shuitangba, Yushe and Mae Moh, all of which are referred to Siamogale. http://zoobank.org/urn:lsid:zoobank.org:pub:5C637018-0772-4C78-AA4B-783B71085D9D © The Trustees of the Natural History Museum, London 2017. All rights reserved.

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... Ma and 12.8-12.2 Ma, respectively;Ginsburg et al., 1983;Grohé et al., 2010; this study); Shuitangba fossil site, latest Miocene of Zhaotong Basin, Yunnan Province, China (~6.2 Ma;Wang et al., 2018); Dapinggou, Pliocene Gaozhuang Formation of Yushe Basin, Shanxi Province, China (~4.9-5.4 Ma;Teilhard de Chardin and Leroy, 1945;Wang et al., 2018). ...
... Ma, respectively;Ginsburg et al., 1983;Grohé et al., 2010; this study); Shuitangba fossil site, latest Miocene of Zhaotong Basin, Yunnan Province, China (~6.2 Ma;Wang et al., 2018); Dapinggou, Pliocene Gaozhuang Formation of Yushe Basin, Shanxi Province, China (~4.9-5.4 Ma;Teilhard de Chardin and Leroy, 1945;Wang et al., 2018). Holotype: MM-54, nearly complete skull dorsoventrally compressed; on the left side, the zygomatic arch and the basicranial region are not preserved; on the right side, the region between the palatine and basioccipital is strongly damaged; right tympanic bulla partially preserved; left I1, C, P3-M1 and alveoli for I2, I3, P2; right I1, I3, C, P3, M1 and alveoli for I2, P2, P4; left i2 or i3; cervical vertebra; stored at PALEVOPRIM, Poitiers (France). ...
... S. bounosa is a derived chronospecies of S. thailandica. In addition, S. bounosa differs from the more derived Chinese S. melilutra (Wang et al., 2018) in its smaller dimensions (tables 1-2), a narrower braincase where the mastoid processes do not extend to the level of the zygomatic arches, absence of a sagittal crest, a morecusped protocone and the presence of an hypoconal crest on P4, a P4 protocone that is more mesially located, a buccal border of P4 that is convex rather than concave, equally developed buccal shelves of paracone and metacone on M1 rather than a more-developed paracone buccal shelf, and a paraconule running closer to the mesial border of M1. ...
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Article
The late middle Miocene fossil-bearing lignite zones of the Mae Moh Basin, northern Thailand, have yielded a rich vertebrate fauna, including two species of Carnivora described thus far: the bunodont otter Siamogale thailandica (known from over a 100 specimens) and the large amphicyonid Maemohcyon potisati. Here we describe additional carnivoran material from Mae Moh comprising new remains of Maemohcyon potisati as well as remains of seven new carnivorans belonging to at least four families: a new species of Siamogale (S. bounosa), a new species of another otter (Vishnuonyx maemohensis), one representative of the genus Pseudarctos (a small amphicyonid), a new genus of Asian palm civet, Siamictis, one representative of another civet (cf. Viverra sp.), a new species of mongoose (Leptoplesictis peignei) and a Feliformia indet. This carnivoran assemblage constitutes one of the richest for the middle Miocene of eastern Asia and by far the richest for the Neogene of Southeast Asia.
... The fossil remains of Lartetictis from Paşalar are stored in the collection facility of Paşalar Excavation Site, Mustafakemalpaşa, Turkey: BP-1986-25c: left P4, almost complete but with a missing parastyle area; BP-alb-016: left complete M1; Bp-1995-1152: right M1 fragment with protocone and lingual platform; BP-1985-56/3: right M1 fragment including paracone, metacone and protocone; BP-1991-1652: right fragment of an hemimandible with p2, p4-m1; BP-1991-1148: left fragment of an hemimandible (same individual than BP-1991-1652) with p4-m1; BP-2017-111: right fragment of an hemimandible with m1; BP-1986-25a: right complete m1; BP-1992-441: right complete m1; BP-2018-R13-74: left fragment of an hemimandible with m1; BP-1986-25b: left m1 trigonid; BP-alb-003: right fragment of m1 including protoconid, Wang et al. 2017 (c. MN13-14, China) were analysed by original publications (Thenius 1949;Petronijevic 1967;Seehuber 2008;Wang et al. 2017). ...
... It has recently been included within Lutrinae by Ginsburg (1999), and Salesa et al. (2013). Wang et al. (2017) noted that some Miocene lineages of otters, especially Mionictis, Lartetictis and Siamogale, have evolved badger-like teeth and, consequently, were often confused with melines. The inclusion of Lartetictis in Melinae and Lutrinae are arguable in part due to the convergences in dentition between these two subfamilies. ...
... The available postcranial remains of the genus correspond to L. dubia from Sansan and Goldberg (Ginsburg 1961;Heizmann and Morlo 1998;Peigné 2012) and suggest a semiaquatic lifestyle. Wang et al. (2017) performed a wide cladistics analysis of Neogene and living otters, but excluded Mionictis and Lartetictis from it, based on the morphology of the upper dentition and their convergence with Melinae. Although, they highlighted the ambiguity of Mionictis with Lutrinae and Melinae. ...
Article
The present paper addresses the study of new fossils of the extinct lutrine Lartetictis Ginsburg & Morales, 1996 from the early middle Miocene of Göriach (Austria, late MN5-early MN6) and from the hominoid locality of Paşalar (Turkey, late MN5). The mandibular material of Lartetictis from Göriach is described and assigned to the type species, Lartetictis dubia. The mandibular and dental specimens from Paşalar proceed from the digging seasons 1983–2018, and constitute one of the larger samples of Lartetictis, enabling us to erect the species Lartetictis pasalarensis sp. nov. Its large size and features that are more derived than those of the Central European L. dubia characterises this new Turkish species. Among other features, L. pasalarensis shows a relatively low and broader P4 protocone, a larger distolingual expansion of the M1 lingual platform, higher cuspids of the m1 and a more trenchant m1 talonid. This new taxon represents the first datum of Lartetictis in Turkey as well as the easternmost record of the genus. Careful comparison between Lartetictis and other extinct otters from the middle Miocene, including Paralutra in Europe, Siamogale in Asia and Mionictis in North America, suggests a closer relationship with the latter group. urn:lsid:zoobank.org:act:74C19A50-91B4-4878-B702-5F8C03E41F4A
... El cráneo de las nutrias se caracteriza por ser ligeramente aplanado con una caja craneana alargada, grandes canales infraorbitarios, arcos cigomáticos relativamente delgados, el inion ubicado anterior a las crestas nucales y el proceso mastoideo expandido ventralmente debajo del meato auditivo (Anexo 1) (2,3). Las mandíbulas poseen ramas cortas con una región sinfisaria procumbente que optimiza la forma hidrodinámica del cráneo (2). ...
... Esto sugiere fuertemente la posibilidad de que el estilo de vida acuático de las nutrias haya aparecido después del desarrollo inicial de la morfología dental distintiva del grupo (5). La segunda presenta rasgos craneales lutrinos y dentición bunodonte, similar a aquella de los tejones (Melinae), que junto a su tamaño corporal gigante y elevada fuerza mandibular representan una ecomorfología de alimentación durófaga sin análogos vivos (3,9). ...
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Thesis
La nutria marina, Lontra felina, es un carnívoro generalista con marcadas diferencias en la dieta a lo largo de su distribución en las costas del Pacífico sudeste, pues las poblaciones del norte (Perú) son principalmente piscívoras, mientras que las del sur (Chile) son predominantemente durófagas (e.g. crustáceos). Diferencias alimenticias existen entre especies vivientes de nutrias (Lutrinae) y han sido asociadas a disparidad en las proporciones del cráneo y la mandíbula. Dado que L. felina no ha sido incluida en análisis cuantitativos, se desconoce si su anatomía corresponde con alguno de los ecomorfotipos establecidos para las nutrias –piscívoro o durófago– y si éste presenta variaciones geográficas o sexuales. El objetivo de este estudio fue establecer el ecomorfotipo de alimentación de Lontra felina en un contexto filogenético e investigar su variación morfológica intraespecífica. Utilizando morfometría geométrica, se cuantificó la morfología craneal y mandibular de especímenes de Lontra felina de Perú y Chile y otras 15 especies de mustélidos. La comparación interespecífica se realizó mediante análisis de componentes principales con mapeo filogenético y las variaciones intraespecíficas se evaluaron usando análisis discriminantes y pruebas de t. Los análisis morfométricos demostraron que la nutria marina presenta un ecomorfotipo alimenticio mixto, con características tanto del piscívoro (cráneos más alargados, planos y estrechos, mandíbulas más alargadas y procesos angulares más grandes) como del durófago (cráneos más cortos, convexos y anchos, áreas molariformes más grandes y mandíbulas más cortas). Los análisis intraespecíficos indicaron la ausencia de dimorfismo sexual, pero revelaron diferencias geográficas en la forma asociadas a la variación latitudinal en la dieta entre Perú y Chile. Así, las poblaciones de Perú exhibieron cráneos más alargados y estrechos, propios del ecomorfotipo piscívoro, y, las de Chile, cráneos más cortos y anchos, típicos del ecomorfotipo durófago. Considerando las diferencias genéticas previamente reportadas, nuestros resultados apoyan la existencia de un proceso de especiación alopátrica en marcha conducido por la dieta y cuyo conocimiento es de relevancia para su conservación.
... The genera Siamogale, Mionictis, and Lartetictis form a diverse group of otter-like mustelids from the middle to late Miocene, found in several localities of Eurasia and North America (e.g., Matthew and Gidley, 1904;Matthew, 1924;Ginsburg and Morales, 1996;Peigné, 2012;Wang et al., 2018;Grohé et al., 2020;. They represent a group with uncertain affinities both among them and with other mustelid groups, being colloquially named as badger-like otters, because of their robust and bunodont dentition (Wang et al., 2018). ...
... The genera Siamogale, Mionictis, and Lartetictis form a diverse group of otter-like mustelids from the middle to late Miocene, found in several localities of Eurasia and North America (e.g., Matthew and Gidley, 1904;Matthew, 1924;Ginsburg and Morales, 1996;Peigné, 2012;Wang et al., 2018;Grohé et al., 2020;. They represent a group with uncertain affinities both among them and with other mustelid groups, being colloquially named as badger-like otters, because of their robust and bunodont dentition (Wang et al., 2018). Vishnuonyx neptuni sp. ...
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Article
This study presents a new species of a large-sized lutrine from the upper Miocene hominid locality of Hammerschmiede, Vishnuonyx neptuni sp. nov., reporting the first occurrence of the genus in Europe and its most northern and western record. The new species differs from the already known members of the genus in size (intermediate between the African Vishnuonyx? angololensis and the Asiatic Vishnuonyx chinjiensis) and morphology, in particular in the larger P4 hypocone, the primitive morphology of M1 (paraconule present, enlarged protoconule and metaconule, labial expansion at the paracone area), the shorter and more robust lower premolars and the wider m1 trigonid. We hypothesized that the dispersal event that led to the expansion of the genus in Europe seems to be correlated with the water connection between Paratethys and the Mesopotamian Basin during the Konkian, between 13.4 and 12.65 Ma. In terms of paleoecology, it is here suggested that this form was feeding mainly on fish and less on bivalves or plant material, resembling the extant giant otter, Pteronura brasiliensis.
... Among the notable mammals discovered at Shuitangba and published so far are a hominoid, cf. Lufengpithecus lufengensis , the oldest occurrence of the gomphotheriid Sinomastodon (Wang et al., 2016), a new species of giant otter, Siamogale melilutra (Wang et al., 2018), and Nesolagus longisinuosus, an early record of the extant swamp rabbit (Flynn et al., 2019). ...
... The avian and nonprimate mammal fauna of Shuitangba also supports an interpretation that the site represents a continuously wet freshwater-margin environment, as evidenced by copious fossils of waterfowl and remains of beavers, giant otters, and swamp rabbits (Zhang et al., 2013;Jablonski et al., 2014;Wang et al., 2018;Flynn et al., 2019). The recent recognition of the swamp rabbit, Nesolagus, at Shuitangba and Lufeng is consistent with a wet, swamp-margin environment (Flynn et al., 2019). ...
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Article
A dentate mandible and proximal femur of Mesopithecus pentelicus Wagner, 1839 are described from the Shuitangba lignite mine in Zhaotong Prefecture, northeastern Yunnan Province, China. The remains were retrieved from sediments just below those that yielded a juvenile Lufengpithecus cranium and are dated at about ∼6.4 Ma. The mandible and proximal femur were found in close proximity and are probably of the same individual. The lower teeth are metrically and morphologically closely comparable with those of confirmed M. pentelicus from Europe, and on this basis, the specimen is assigned to this species. The anatomy of the proximal femur indicates that the Shuitangba Mesopithecus was a semiterrestrial quadruped that engaged in a range of mostly arboreal activities, including walking, climbing, and occasional leaping, with an abducted hip joint. The Shuitangba Mesopithecus is dentally typical for the genus but may have been more arboreal than previously described for M. pentelicus. M. pentelicus is well known from late Miocene (MN 11–12) sites in Europe and southwest Asia. Its estimated average rate of dispersal eastward was relatively slow, although it could have been episodically more rapid. The presence of a colobine, only slightly lower in the same section at Shuitangba that produced Lufengpithecus, is one of the only two well-documented instances of the near or actual co-occurrence of a monkey and ape in the Miocene of Eurasia. At Shuitangba, M. pentelicus occupied a freshwater-margin habitat with beavers, giant otters, swamp rabbits, and many aquatic birds. The presence of M. pentelicus in southwest China near the end of the Miocene further attests to the ecological versatility of a species long recognized as widespread and adaptable. The modern colobines of Asia, some or all of which are probable descendants of Mesopithecus, have gone on to inhabit some of the most highly seasonal and extreme habitats occupied by nonhuman primates.
... The oldest Thai S. thailandica was initially described by a lower carnassial (Ginsburg et al., 1983), then by over a hundred of fragmentary jaws and isolated teeth (Grohé et al., 2010). The third species of Siamogale, from latest Miocene deposits of the Zaotong Basin, Yunnan Province of China, and from the early Pliocene of the Yushe Basin, Shanxi Province of China, is a wolf-sized otter (Wang et al., 2018), which shows more derived morphological features compared to the Mae Moh species. Siamogale belongs to a south and eastern Asian clade of bunodont otters (Wang et al., 2018), for which the teeth and the mandibular apparatus are specialized for crushing hard and/or abrasive food items (Tseng et al., 2017). ...
... The third species of Siamogale, from latest Miocene deposits of the Zaotong Basin, Yunnan Province of China, and from the early Pliocene of the Yushe Basin, Shanxi Province of China, is a wolf-sized otter (Wang et al., 2018), which shows more derived morphological features compared to the Mae Moh species. Siamogale belongs to a south and eastern Asian clade of bunodont otters (Wang et al., 2018), for which the teeth and the mandibular apparatus are specialized for crushing hard and/or abrasive food items (Tseng et al., 2017). Vishnuonyx maemohensis is a new species of Vishnuonyx, a genus previously recorded mostly by upper teeth from the Siwaliks and Eastern Africa (Pilgrim, 1932;Werdelin, 2003). ...
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Article
The present 3D Dataset contains the 3D models described and figured in the following publication: Grohé et al. 2020, the late middle Miocene Mae Moh Basin of northern Thailand: the richest Neogene assemblage of Carnivora from Southeast Asia and a paleobiogeographic analysis of Miocene Asian carnivorans. American Museum Novitates.
... No diastemas are present in the mandible. The m1 is elongated, widest at the trigonid, with a buccal cingulid reaching to the anteriormost point of the tooth, a postmetacristid (= metastylid in Wang et al. 2017) that slopes down in a flat angle and is connected to the lingual talonid edge (= entocristid), an elongated and low talonid with the hypoconid being the highest cusp, a small hypoconulid present at the labio-distal corner, and the lingual edge of the talonid smooth or with minute cuspules. In Late Miocene species, the length/width index exceeds 2.5. ...
... Late Trochictis clusters parallel to the lutrine Paralutra ( Figure 4) and a group containing the gulonine Martes, the mephitid Proputorius, and the ictonychines. We interpret the lack of a widened talonid in m1 (character 14, see Appendix C and Wang et al. 2017) as an important character to separate easily Trochictis from Taxodon, the leptarctine Trocharion, Promeles, the mephitid Plesiomeles, and the lutrine Paralutra. It is noteworthy, that the debated Lartetictis has a narrow talonid, as well, adding evidence that the taxon is no lutrine (e.g., Ginsburg 1968;Heizmann and Morlo 1998). ...
Article
We present the first record of the mustelid Trochictis from the Late Miocene (MN 9/10) of Germany, a partial mandible with p4, m1, and m2 from Eppelsheim. Trochictis peignei sp. nov. is characterised by the combination p4 with a distal accessory cuspid and a basal lingual enlargement, m1 with a length/width index larger than 2.5, a rounded lingual wall of the paraconid, an entoconulid present, the metaconid as high as the paraconid, and cuspules present on the posterior talonid edge, and m2 with a very reduced talonid. Comparison to similar sized Middle and Late Miocene mustelids and a stratocladistic analysis place T. peignei sp. nov. closest to T. narcisoi from MN 9 of Can Llobateras, T. depereti from several MN 6 to MN 7/8 European localities, and cf. Trochictis sp. from MN 9 of Rudabánya. We also suggest synonymy of T. carbonaria and T. artenensis and verify that m2 of Trochictis occasionally is double-rooted. The analysis does not corroborate a close relationship of Trochictis to Taxodon or the subfamily Ictonychinae, but can also not discard confidently such an assignment. With a body mass of about 3 kg, Trochictis peignei sp. nov. represents the hitherto smallest described carnivoran of the Eppelsheim Formation.
... Plio-Pleistocene otters with robust lophid dentitions were widely distributed in the Old World. In East Asia, Siamogale melilutra has been reported from the early Pliocene Dapinggou locality in the Yushe Basin, northern China (Teilhard de Chardin and Leroy 1945; Wang et al. 2017). In general, this species is similar anatomically to Aonyx in possessing robust teeth and a deep anterior mandible, although the affinity of these two taxa is not supported in a recent phylogenetic analysis (Wang et al. 2017). ...
... In East Asia, Siamogale melilutra has been reported from the early Pliocene Dapinggou locality in the Yushe Basin, northern China (Teilhard de Chardin and Leroy 1945; Wang et al. 2017). In general, this species is similar anatomically to Aonyx in possessing robust teeth and a deep anterior mandible, although the affinity of these two taxa is not supported in a recent phylogenetic analysis (Wang et al. 2017). The size of Siamogale melilutra is much larger than that of Amblonyx barryi sp. ...
Article
Material of Indarctos and other Caniformia fossils from the Yale Peabody Museum G.E. Lewis Siwalik expedition collections from Pakistan and northern India are described herein. The M2 of a newly described cranium of Indarctos from the Dhok Pathan Zone is extremely similar to the holotype of Indarctos salmontanus, and both materials are similar to European I. atticus, thus both the holotype of I. ‘salmontanus’ and the new material from the Siwaliks can be assigned to I. atticus. ‘Indarctos’ punjabiensis from the Dhok Pathan Zone is markedly different from I. atticus and other known species of Indarctos in having a much shorter M2 talon and probably represents another genus. A hemicyonid from the Chinji Zone is reported in the Siwaliks for the first time. Plesiogulo from the Dhok Pathan Zone is identified as Plesiogulo aff. crassa, differing slightly from Chinese Plesiogulo crassa, P. brachygnathus and all North American species. The earliest member of the small clawed otter lineage, Amblonyx barryi sp. nov., from the Tatrot Zone in the Siwaliks already shows several mandibular and dentition traits characteristic of the genus. An amphicyonid (aff. Magericyon sp.), a gulonine mustelid (aff. Iberictis sp.), and the lutrine mustelid Sivaonyx gandakasensis are also reported.
... As sea otters spend more of their time in the water than the giant otter (Kenyon 1969;Estes 1989), we predict more pseudogenization in the sea otter lineage than the giant otter. However, because both otters are part of a relatively recent semiaquatic radiation (<10 Ma; Willemsen 1992;Wang et al. 2018), we also predict that fewer sensory genes will be pseudogenized in the otter lineages than in more ancient and fully aquatic marine mammals, such as pinnipeds, sirenians, and cetaceans (Kishida et al. 2007(Kishida et al. , 2015Hayden et al. 2010;Jiang et al. 2012;Feng et al. 2014;Li and Zhang 2014;Hughes et al. 2018). ...
... The first evidence of aquatic adaptations in the otter lineage are found in lutrine remains from Middle Miocene deposits (Willemsen 1992;Wang et al. 2018) and further fossils indicate that the sea otter (E. lutris) entered the North Pacific Ocean in the Pliocene-Pleistocene, 1-3 Ma (Riedman and Estes 1990;Boessenecker 2018). ...
Article
Despite its recent invasion into the marine realm, the sea otter (Enhydra lutris) has evolved a suite of adaptations for life in cold coastal waters, including limb modifications and dense insulating fur. This uniquely dense coat led to the near-extinction of sea otters during the 18th-20th century fur trade and an extreme population bottleneck. We used the de novo genome of the southern sea otter (E. l. nereis) to reconstruct its evolutionary history, identify genes influencing aquatic adaptation, and detect signals of population bottlenecks. We compared the genome of the southern sea otter to the tropical freshwater-living giant otter (Pteronura brasiliensis) to assess common and divergent genomic trends between otter species, and to the closely related northern sea otter (E. l. kenyoni) to uncover population-level trends. We found signals of positive selection in genes related to aquatic adaptations, particularly limb development and polygenic selection on genes related to hair follicle development. We found extensive pseudogenization of olfactory receptor genes in both the sea otter and giant otter lineages, consistent with patterns of sensory gene loss in other aquatic mammals. At the population level, the southern sea otter and the northern sea otter showed extremely low genomic diversity, signals of recent inbreeding, and demographic histories marked by population declines. These declines pre-date the fur trade and appear to have resulted in an increase in putatively deleterious variants that could impact the future recovery of the sea otter.
... In fact, the relationship between the unadjusted SE values and model volumes of living otter species is significantly linear (Fig. 3c, Table 3). This stiffness-volume linearity is a relationship expected from isometric scaling of a given finite element model with input forces set proportional to surface area 5 3 Left lower jaws with temporalis and masseter attachment sites labeled in red are shown for each species. Jaws are scaled to the same length for visual comparison. ...
... The contemporaneous fauna at Shuitangba, where the type specimens of Siamogale melilutra were discovered, contains common mammalian species of southeast Asian late Miocene forested habitats (deer, tapir, proboscideans, beavers) as well as aquatics plants such as fox nuts 3 . The abundance of aquatic and near-water environments in that region 18 may have allowed aquatic carnivorans such as Siamogale to become the dominant predators of their ecological communities, outcompeting the larger, more cursorial carnivorans commonly found in more open environments outside of the Shuitangba area. ...
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Article
At 50 kg in estimated weight, the extinct Siamogale melilutra is larger than all living otters, and ranks among the largest fossil otters. The biomechanical capability of S. melilutra jaws as related to their large size is unknown but crucial to reconstructing the species’ potentially unique ecological niche. Here we compare the mandibular biomechanics of S. melilutra using engineering-based performance measures against ten extant otter biomechanical models. Despite a wide range of feeding preferences from durophagy to piscivory, living otter species exhibit a linear relationship between mandible stiffness and volume, as expected in isometric model scaling. In contrast, S. melilutra models exhibit a six-fold increase in stiffness from expected stiffness-volume relationships calculated from extant species models. Unlike stiffness, mechanical efficiency of biting is conserved among living otters and in S. melilutra. These findings indicate that although similar to living bunodont otters in morphology and biting efficiency, jaw strength in S. melilutra far surpasses molluscivores such as sea otters and Cape clawless otters, even after accounting for size. Therefore, Siamogale represents a feeding ecomorphology with no living analog, and its giant size and high mandibular strength confer shell-crushing capability matched only by other extinct molluscivores such as the marine bear Kolponomos.
... Although ocean-going otters had to have evolved from freshwater ancestors [2], the fossil record of the North American sea otters is poor, and the evolutionary origin of extant sea otters remains uncertain [3]. Recent phylogenetic analyses of morphological and genetic sequence data suggest that Enhydra is most closely related to Asian fossil otters, whereas earlier palaeontological analyses indicate a close relationship between Enhydra and the fossil otter Enhydritherium terraenovae [4]. The hypothesis of a North American fossil otter population related to Enhydritherium giving rise to the present day sea otter Enhydra is appealing because the majority (eight out of nine) of the fossil localities containing Enhydritherium specimens also have marine vertebrates associated with them [5] (electronic supplementary material, table S1). ...
... In contrast, our discovery of Enhydritherium in central Mexico suggests that a land-based route was much more likely, in terms of shorter distance (less than 4000 km), and is supported by fossils from an entirely land-locked basin containing upper Miocene fluviolacustrine deposits [6]. A recent study of fossil Enhydra records indicates that sea otters may have dispersed into the eastern Pacific from the North Atlantic not much earlier than middle Pleistocene [3]; this biogeographic scenario, plus recent cladistics analyses indicating a distant relationship between Enhydritherium and extant sea otters [4], and the new fossil evidence presented in this report, together suggest that the previously proposed close relationship between Enhydra and Enhydritherium is not supported [8]. ...
Article
The North American fossil otter Enhydritherium terraenovae is thought to be partially convergent in ecological niche with the living sea otter Enhydra lutris, both having low-crowned crushing teeth and a close association with marine environments. Fossil records of Enhydritherium are found in mostly marginal marine deposits in California and Florida; despite presence of very rich records of fossil terrestrial mammals in contemporaneous localities inland, no Enhydritherium fossils are hitherto known in interior North America. Here we report the first occurrence of Enhydritherium outside of Florida and California, in a land-locked terrestrial mammal fauna of the upper Miocene deposits of Juchipila Basin, Zacatecas State, Mexico. This new occurrence of Enhydritherium is at least 200 km from the modern Pacific coastline, and nearly 600 km from the Gulf of Mexico. Besides providing further evidence that Enhydritherium was not dependent on coastal marine environments as originally interpreted, this discovery leads us to propose a new east-to-west dispersal route between the Florida and California Enhydritherium populations through central Mexico. The proximity of the fossil locality to nearby populations of modern neotropical otters Lontra longicaudis suggests that trans-Mexican freshwater corridors for vertebrate species in riparian habitats may have persisted for a prolonged period of time, pre-dating the Great American Biotic Interchange.
... Molecular dating has estimated that Lutrinae arose ~8-9 million years ago in the late Miocene (Yonezawa et al. 2007;Koepfli et al. 2008;Sato et al. 2009Eizirik et al. 2010). The late Miocene fossil record of otters and otter-like mustelids, which exhibit adaptations indicative of feeding on fish, molluscs, or crustaceans (Morales and Pickford 2005;Pickford 2007;Haile-Selassie 2008;Peigné et al. 2008;Villier et al. 2011;Tseng et al. 2017;Wang et al. 2018), suggests that the switch to diets low in sweet and umami taste-eliciting compounds occurred Table 1. Mutations hypothesized to cause evolutionary events of loss of the sweet taste receptor in Carnivora. ...
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Controversy and misunderstanding surround the role of feeding specialization in taste receptor loss in vertebrates. We refined and tested the hypothesis that this loss is caused by feeding specializations. Specifically, feeding specializations were proposed to trigger time-dependent process of taste receptor loss through deprivation of benefit of using the receptor’s gustatory function. We propose that this process may be accelerated by abiotic environmental conditions or decelerated/stopped because of extragustatory functions of the receptor’s protein(s). As test case we used evolution of the sweet (TAS1R2+TAS1R3) and umami (TAS1R1+TAS1R3) receptors in Carnivora (dogs, cats, and kin). We predicted these receptors’ absence/presence using data on presence/absence of inactivating mutations in these receptors’ genes and data from behavioral sweet/umami preference tests. We identified 20 evolutionary events of sweet (11) or umami (9) receptor loss. These events affected species with feeding specializations predicted to favor sweet/umami receptor loss (27 and 22 species, respectively). All species with feeding habits predicted to favor sweet/umami receptor retention (11 and 24, respectively) were found to retain that receptor. Six species retained the sweet (5) or umami (1) receptor despite feeding specialization predicted to favor loss of that receptor, which can be explained by the time dependence of sweet/umami receptor loss process and the possible decelerating effect of TAS1R extragustatory functions so that the sweet/umami receptor process is ongoing in these species. Our findings support the idea that feeding specialization leads to taste receptor loss and is the main if not only triggering factor for evolutionary loss of taste receptors.
... The Mazegou Formation of the Yushe Basin, Shanxi is the horizon yielding the richest fossils of Late Pliocene large mammals, and 65 forms have been currently preliminarily identified (Flynn et al., 1991;Deng and Hou, 2011;Wang et al., 2017), which contains nearly all species of large mammals from Late Pliocene localities in North China. It is therefore a helpful standard to compare with when trying to determine if the age of a fauna is Late Pliocene. ...
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Currently, there are still different views regarding the chronology of the Late Cenozoic deposits in the Nihewan Basin, which results from the contradiction between biostratigraphic correlations based on mammalian fossils and magnetostratigraphic dating results. Biostratigraphic correlations indicate that the aeolian red clay exposed in the Sanggan River canyon, the fluvio-lacustrine red clay with sands and gravels, and the sandy clay of swamp facies on both sides of the lower reaches of the Huliu River belong to the Upper Pliocene, whereas the magnetostratigraphic dating usually correlates them to the Lower Pleistocene. In October 2011, a collection of mammalian fossils was unearthed from a block of collapsed deposits at Yegou in the Nihewan Basin, which is about 300 m north of the Laowogou section that is well known for the Pliocene mammalian fossils from its lower part. The Yegou fossils are identified herein as 10 species in 9 genera: Nyctereutes tingi, N. sinensis, Pachycrocuta pyrenaica, Homotherium sp., Hipparion (Plesiohipparion) houfenense, Dicerorhinus sp., Muntiacus sp., Axis shansius, Gazella blacki, and Paracamelus sp. The fauna is quite different from the classic Early Pleistocene Nihewan Fauna in composition and provides new evidence for the existence of the Upper Pliocene in the Nihewan Basin. Based on a systematic description of the fauna, its composition and geological age are discussed, and the compositional features of large mammals of the Late Pliocene and the Early Pleistocene mammalian faunas in the Nihewan Basin are summarized.
... However, the stratigraphic range of this species covers from the Early Miocene (Pellecahus; MN 4; [119]) to the early Late Miocene, as it has been found in Rudabánya (MN 9; [65]). The species "Paralutra garganensis" Willemsen, 1983 [122], was recently suggested to belong to a different genus [123]. ...
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The present study deals with new material of carnivorans (Mustelidae, Mephitidae, Ailuridae, Potamotheriinae and Viverridae) from the basal Tortonian (Late Miocene, late Astaracian) hominid-bearing locality of Hammerschmiede (Bavaria, Germany). The small carnivoran fauna includes 20 species belonging to nine different subfamilies (Guloninae, Lutrinae, Mellivorinae, Potamotheriinae, Leptarctinae, Mephitinae, Simocyoninae, Genettinae and Viverrinae). The identified forms include: “Martes” sansaniensis, “Martes” cf. munki, “Martes” sp., Circamustela hartmanni n. sp., Laphyctis mustelinus, Guloninae indet., Eomellivora moralesi, Vishnuonyx neptuni, Paralutra jaegeri, Lartetictis cf. dubia, Trocharion albanense, Palaeomeles pachecoi, Proputorius sansaniensis, Proputorius pusillus, Alopecocyon goeriachensis, Simocyoninae indet., Potamotherium sp., Semigenetta sansaniensis, Semigenetta grandis and Viverrictis modica. The new species Circamustela hartmanni n. sp. is differentiated from the other members of the genus by its small size and the morphology of its dental cusps in the upper and lower carnassials. This is one of the highest reported taxonomic diversities for fossil small carnivorans in the Miocene of Europe, including also first and last occurrences for several genera and species. Additionally, the assemblage comprises some rare taxa such as Palaeomeles pachecoi and Eomellivora moralesi. An ecomorphological comparison of the discovered taxa reveals possible cases of competition and niche partitioning.
... Various methods have been proposed to retrodeform taphonomically distorted fossilised skeletal remains, such as rearticulation of broken fragments (e.g., Zollikofer et al., 2005;Nyakatura et al., 2015;Porro et al., 2015;Di Vincenzo et al., 2017;Wang et al., 2018), morphing reference models (Gunz et al., 2009;Vidal and Díez Díaz, 2017), and the use of landmarks (e.g., Gunz et al., 2009;Molnar et al., 2012;Tallman et al., 2014;Lautenschlager, 2016;Schlager et al., 2018;Cirilli et al., 2020). In particular, retrodeformation has been applied to bilaterally symmetrical objects, such as cranial or axial elements, as these may offer reference points from which the directionality of plastic deformation can be deduced (Ogihara et al., 2006;Arbour and Currie, 2012;Cuff and Rayfield, 2015;Nyakatura et al., 2015;Lautenschlager, 2016;Schlager et al., 2018). ...
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Taphonomic and diagenetic processes inevitably distort the original skeletal morphology of fossil vertebrate remains. Key aspects of palaeobiological datasets may be directly impacted by such morphological deformation, such as taxonomic diagnoses and phylogenetic hypotheses, interpretations of the shape and orientation of anatomical structures, and assessments of interspecific and intraspecific variation. In order to overcome these ubiquitous challenges we present a novel reconstruction workflow combining retopology and retrodeformation, allowing the original morphology of both symmetrically and asymmetrically damaged areas of fossils to be reconstructed. As case studies, we present idealised three-dimensional reconstructions of the sternum of the crownward stem-bird Ichthyornis dispar, and cervical vertebrae of the diplodocid sauropod Galeamopus pabsti. Multiple Ichthyornis sterna were combined into a single, idealised composite representation through superimposition and alignment of retopologised models, and this composite was subsequently retrodeformed. The Galeamopus vertebrae were individually retrodeformed and symmetrised. Our workflow enabled us to quantify deformation of individual specimens with respect to our reconstructions, and to characterise global and local taphonomic deformation. Our workflow can be integrated with geometric morphometric approaches to enable quantitative morphological comparisons among multiple specimens, as well as quantitative interpolation of "mediotypes" of serially homologous elements such as missing vertebrae, haemal arches, or ribs.
... The Mazegou Formation of the Yushe Basin, Shanxi is the horizon yielding the richest fossils of Late Pliocene large mammals, and 65 forms have been currently preliminarily identified (Flynn et al., 1991;Deng and Hou, 2011;Wang et al., 2017), which contains nearly all species of large mammals from Late Pliocene localities in North China. It is therefore a helpful standard to compare with when trying to determine if the age of a fauna is Late Pliocene. ...
Preprint
Currently, there are still different views regarding the chronology of the Late Cenozoic deposits in the Nihewan Basin, which results from the contradiction between biostratigraphic correlations based on mammalian fossils and magnetostratigraphic dating results. Biostratigraphic correlations indicate that the aeolian red clay exposed in the Sanggan River canyon, the fluvio-lacustrine red clay with sands and gravels, and the sandy clay of swamp facies on both sides of the lower reaches of the Huliu River belong to the Upper Pliocene, whereas the magnetostratigraphic dating usually correlates them to the Lower Pleistocene. In October 2011, a collection of mammalian fossils was unearthed from a block of collapsed deposits at Yegou in the Nihewan Basin, which is about 300 m north of the Laowogou section which is well known for the Pliocene mammalian fossils from its lower part. The Yegou fossils are identified herein as 10 species in 9 genera: Nyctereutes tingi, N. sinensis, Pachycrocuta pyrenaica, Homotherium sp., Hipparion (Plesiohipparion) houfenense, Dicerorhinus sp., Muntiacus sp., Axis shansius, Gazella blacki, and Paracamelus sp. The fauna is quite different from the classic Early Pleistocene Nihewan Fauna in composition and provides new evidence for the existence of the Upper Pliocene in the Nihewan Basin. Based on a systematic description of the fauna, its composition and geological age are discussed, and the compositional features of large mammals of the Late Pliocene and the Early Pleistocene mammalian faunas in the Nihewan Basin are summarized.
... In the most recent combined phylogeny of otters, the extant sea otter Enhydra lutris and its sister taxon Enhydriodon spp. are embedded within the river otter (Lutrinae) clade (Wang et al., 2018). Although this same phylogenetic analysis placed Enhydritherium with other lutrine otters and distant from the sea otter we included it in our study since recent fossil evidence suggested that Enhydritherium occupied freshwater environments in addition to estuarine and coastal environments (Tseng et al., 2017). ...
... In Thailand, Semigenetta is doubtfully recorded from the Miocene locality of Li Mae Long and it is confidently reported from the middle Miocene of Mae Moh. In Mae Moh, three other taxa suggest a connection with Europe: the amphicyonid Pseudarc tos and the herpestid Leptoplesictis, both known in Europe since the early Miocene, as well as the lutrine Siamogale, whose ancestral form could be the European early Miocene Paralutra (Grohé et al. 2010;Wang et al. 2018;Grohé et al. 2020a). In Asia, as a result of the elevation of the Himalayan Mountains and Tibetan Plateau, the Oriental and Palaearctic biogeographic provinces could have emerged during the early Miocene (Wang et al. 2013). ...
The study and reanalysis of late Oligocene and middle Miocene dental material from Thailand provides evidence for long-distance stratigraphic correlations, and thus sheds new light on past terrestrial connections between Southeastern Asia and Europe. Here we report the oldest occurrence of Ursidae in southern Asia – a late Oligocene fossil from Nong Ya Plong previously referred to Mustelida but reattributed here to Cephalogale aff. geoffroyi (Ursidae, Hemicyoninae, Cephalogalini). We also describe a new Viverridae, Semigenetta cf. steinheimensis, from the middle Miocene carnivoran-rich locality of Mae Moh. The presence of these two taxa in Western Europe reinforces stratigraphic correlations of the MP29 and MN7–8 fossil sites with Southeast Asian localities. Members of the tribe Cephalogalini may have migrated several times from Asia to Europe, or vice-versa, during the Oligocene and early Miocene via either a northern route across northern China, or a southern route traversing southern Asia and the Middle East. Semigenetta could have dispersed along a corridor through Central Asia or a southern Asian route into Thailand during the middle Miocene. Our study thus indicates that medium- or large-sized carnivorans constitute a useful tool for reconstructing the paleobiogeography of extinct species.
... In the most recent combined phylogeny of otters, the extant sea otter Enhydra lutris and its sister taxon Enhydriodon spp. are embedded within the river otter (Lutrinae) clade (Wang et al., 2018). Although this same phylogenetic analysis placed Enhydritherium with other lutrine otters and distant from the sea otter we included it in our study since recent fossil evidence suggested that Enhydritherium occupied freshwater environments in addition to estuarine and coastal environments (Tseng et al., 2017). ...
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Marine mammals are key components of aquatic ecosystems. Feeding strategies identified in extant cetaceans, pinnipeds, sirenians, marine otters, and polar bears are associated with anatomical specializations of the head (rostrum, palate, temporomandibular joint, teeth/baleen, mandible). Genetic and ontogenetic evidence of skull and tooth morphology provide the mechanisms that underlie patterns of feeding diversity. Based on a comprehensive diversity data set derived from the Paleobiology Database, we considered feeding strategies (suction, biting, filter feeding, grazing), prey type (squid, fish, benthic invertebrates, zooplankton, tetrapods, sea grasses), tooth pattern and cusp shape (homodont, heterodont, pointed, rounded, edentulous), and habitat (marine, riverine, estuarine) in fossil and extant marine mammals. These variables were then tested for correlation and their changes through time examined in relation to productivity and climate variables. We provide an integrated analysis of the evolution of feeding and trophic structure in marine mammals and explore the origin and timing of particular feeding strategies over the last 50 million years. In agreement with earlier reports, updated generic counts reveal that the greatest diversity of pinnipedimorphs and cetaceans occurred during the late Miocene (Tortonian), following the Mid-Miocene Climatic Optimum. These historical data are used as a framework to inform past and present structure and trophic interactions and enable predictions about future marine ecosystems.The drivers of diet and feeding patterns are both environmental (sea level fluctuations, climate change) and biotic (anatomical specializations, competition, predator-prey). The influence of these processes on paleodiversity varies depending on taxonomic group, timing, and geographic scale.
... To date the phylogeny and coestimate the times and evolutionary rates, a "total-evidence dating" approach, was employed (Pyron, 2011;Ronquist et al., 2012bRonquist et al., , 2016Gavryushkina et al., 2016;Lee, 2016;Zhang et al., 2016;Wang et al., 2017). Also known as fossiltip calibration, this approach allows for the simultaneous analysis of extant and extinct taxa, integrating known age ranges of extinct taxa (directly associated with fossil tips) to infer phylogeny, divergence times, and macroevolutionary parameters (Ronquist et al., 2012a). ...
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In the present study, a series of phylogenetic analyses of morphological, molecular, and combined morphological-molecular datasets were conducted to investigate the relationships of 23 extant and 44 fossil caniforme genera, in order to test the phylogenetic position of putative stem pinniped Puijila within a comprehensive evolutionary framework. With Canis as an outgroup, a Bayesian Inference analysis employing tip-dating of a combined molecular-morphological (i.e., Total Evidence) dataset recovered a topology in which musteloids are the sister group to a monophyletic pinniped clade, to the exclusion of ursids, and recovered Puijila and Potamotherium along the stem of Pinnipedia. A similar topology was recovered in a parsimony analysis of the same dataset. These results suggest the pinniped stem may be expanded to include additional fossil arctoid taxa, including Puijila, Potamotherium, and Kolponomos. The tip-dating analysis suggested a divergence time between pinnipeds and musteloids of ~45.16 million years ago (Ma), though a basal split between otarioids and phocids is not estimated to occur until ~26.52 Ma. These results provide further support for prolonged freshwater and nearshore phases in the evolution of pinnipeds, prior to the evolution of the extreme level of aquatic adaptation displayed by extant taxa. Ancestral character state reconstruction was used to investigate character evolution, to determine the frequency of reversals and parallelisms characterizing the three extant clades within Pinnipedia. Although the phylogenetic analyses did not directly provide any evidence of parallel evolution within the pinniped extant families, it is apparent from the inspection of previously-proposed pinniped synapomorphies, within the context of a molecular-based phylogenetic framework, that many traits shared between extant pinnipeds have arisen independently in the three clades. Notably, those traits relating to homodonty and limb-bone specialization for aquatic locomotion appear to have multiple origins within the crown group, as suggested by the retention of the plesiomorphic conditions in early-diverging fossil members of the three extant families. Thus, while the present analysis identifies a new suite of morphological synapomorphies for Pinnipedia, the frequency of reversals and other homoplasies within the clade limit their diagnostic value.
... The Shuitangba fauna included a tapir (Ji et al., 2015) and diverse waterfowl. At Shuitangba a large otter (Wang et al., 2018) also attests to water. The Shuitangba ape (Ji et al., 2013) is very similar to Lufengpithecus lufengensis, and these suggest dependable sources of food (likely fruit) at both sites. ...
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Abstract The rabbit from the Late Miocene Shuitangba site in Yunnan Province represents the same species as that from the older site of Lufeng, Yunnan. Both settings record a wet, swampy habitat. Premolar morphology shows that the species is an early representative of the extant striped rabbit genus, which today lives in moist habitat, and should be designated Nesolagus longisinuosus (Qiu and Han, 1986). Fossil evidence for Nesolagus by about 7 Ma in the fossil record of South China is consistent with mitochondrial evidence for the Late Miocene split of the extant species of Nesolagus. We reconstruct a scenario for the origin of Nesolagus after 8 Ma, followed by rapid spread through Southeast Asia into present-day Sumatra.
... The Shuitangba fauna included a tapir (Ji et al., 2015) and diverse waterfowl. At Shuitangba a large otter (Wang et al., 2018) also attests to water. The Shuitangba ape (Ji et al., 2013) is very similar to Lufengpithecus lufengensis, and these suggest dependable sources of food (likely fruit) at both sites. ...
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The rabbit from the Late Miocene Shuitangba site in Yunnan Province represents the same species as that from the older site of Lufeng, Yunnan. Both settings record a wet, swampy habitat. Premolar morphology shows that the species is an early representative of the extant striped rabbit genus, which today lives in moist habitat, and should be designated Nesolagus longisinuosus (Qiu & Han, 1986). Fossil evidence for Nesolagus by about 7 Ma in the fossil record of South China is consistent with mitochondrial evidence for the Late Miocene split of the extant species of Nesolagus. We reconstruct a scenario for the origin of Nesolagus after 8 Ma, followed by rapid spread through Southeast Asia into present-day Sumatra.
... These traits are useful for opportunistic foraging and also for crushing bones, as is the case among extant canids (Sillero-Zubiri 2009). This set of traits together (the possession of a mesiodistal enlargement of the M1 lingual platform and the presence of a concavity on the lingual edge) are also present in some lineages of Euroasiatic Miocene lutrines such as Paralutra jaegeri, Lartetictis dubia, and Siamogale thailandica, which have been interpreted recently as badger-like otters (Wang et al. 2017) because their dentition is adapted for crushing food. Thus, the interpretation of these features found in these gulonines, lutrines, and also in melines as a convergence due to a dietary shift toward a more omnivorous or durophagous diet is reasonable. ...
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We describe new dental remains of the genus Iberictis (Carnivora: Mustelidae) from the late early Miocene of the Iberian Peninsula. The new fossils of Iberictis azanzae from Artesilla (16.5–16.3 Ma, MN4; Calatayud-Teruel Basin, Zaragoza, Spain) add important morphological information about this species. Material from another species, Iberictis buloti, is described from els Casots (16.5–16.3 Ma, MN4; Vallès-Penedès Basin, Barcelona, Spain). This material constitutes the most complete sample of Iberictis and the first record of I. buloti in the Iberian Peninsula. Our analyses confirm the taxonomic validity of both species, and confirm the more plesiomorphic status of I. buloti compared to I. azanzae. Reexamination of large mustelid Miocene genera (Dehmictis, Ekorus, Eomellivora, Hoplictis, Iberictis, Ischyrictis, and Plesiogulo) and their inclusion for the first time in a cladistic analysis indicate that Iberictis is the sister taxon of Plesiogulo, and that these genera constitute the sister group of the extant wolverine (Gulo gulo). Our analysis thus confirms a close relationship between the early Miocene Iberictis, the late Miocene Plesiogulo, and the Plio-Pleistocene Gulo. Iberictis is the oldest member of Gulonini, the total clade of wolverines, thereby tracking the fossil record of this clade back to the early Miocene. We further propose a new systematic arrangement for the aforementioned large Miocene mustelids into the subfamilies Guloninae, Mellivorinae, and Mustelinae.
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Taxon sampling is a central aspect of phylogenetic study design, but it has received limited attention in the context of total-evidence dating, a widely used dating approach that directly integrates molecular and morphological information from extant and fossil taxa. We here assess the impact of commonly employed outgroup sampling schemes and missing morphological data in extant taxa on age estimates in a total-evidence dating analysis under the uniform tree prior. Our study group is Pimpliformes, a highly diverse, rapidly radiating group of parasitoid wasps of the family Ichneumonidae. We analyze a data set comprising 201 extant and 79 fossil taxa, including the oldest fossils of the family from the Early Cretaceous and the first unequivocal representatives of extant subfamilies from the mid Paleogene. Based on newly compiled molecular data from ten nuclear genes and a morphological matrix that includes 222 characters, we show that age estimates become both older and less precise with the inclusion of more distant and more poorly sampled outgroups. These outgroups not only lack morphological and temporal information, but also sit on long terminal branches and considerably increase the evolutionary rate heterogeneity. In addition, we discover an artefact that might be detrimental for total-evidence dating: “bare-branch attraction”, namely high attachment probabilities of certain fossils to terminal branches for which morphological data are missing. Using computer simulations, we confirm the generality of this phenomenon and show that a large phylogenetic distance to any of the extant taxa, rather than just older age, increases the risk of a fossil being misplaced due to bare-branch attraction. After restricting outgroup sampling and adding morphological data for the previously attracting, bare branches, we recover a Jurassic origin for Pimpliformes and Ichneumonidae. This first age estimate for the group not only suggests an older origin than previously thought, but also that diversification of the crown group happened well before the Cretaceous-Paleogene boundary. Our case study demonstrates that in order to obtain robust age estimates, total-evidence dating studies need to be based on a thorough and balanced sampling of both extant and fossil taxa, with the aim of minimizing evolutionary rate heterogeneity and missing morphological information.
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Giant mustelids are a paraphyletic group of mustelids found in the Neogene of Eurasia, Africa and North America. Most are known largely from dental remains, with their postcranial skeleton mostly unknown. Here, we describe new craniodental and postcranial remains of the large lutrine Sivaonyx hendeyi and the leopard-size gulonine Plesiogulo aff. monspessulanus from the early Pliocene site Langebaanweg, South Africa. The new material of the endemic S. hendeyi, includes upper incisors and premolars, and fragmentary humerus, ulna and a complete astragalus. Its postcrania shares more traits with the living Aonyx capensis than the late Miocene Sivaonyx beyi from Chad. Sivaonyx hendeyi could therefore be tentatively interpreted as a relatively more aquatic taxon than the Chadian species, comparable to A. capensis. The new specimens of Plesiogulo comprise two edentulous maxillae, including one of a juvenile individual with incomplete decidual dentition, and a fragmentary forelimb of an adult individual. The new dental measurements point to this form being amongst the largest specimens of the genus. Both P3-4 differs from the very large species Plesiogulo botori from late Miocene of Kenya and Ethiopia. This confirms the existence of two distinct large species of Plesiogulo in Africa during the Mio/Pliocene, P. botori in the Late Miocene of Eastern Africa (6.1-5.5 Ma) and Plesiogulo aff. monspessulanus at the beginning of the Pliocene in southern Africa (5.2 Ma). Lastly, we report for the first time the presence of both Sivaonyx and Plesiogulo in MPPM and LQSM at Langebaanweg, suggesting that the differences observed from the locality may be produced by sedimentation or sampling biases instead of temporal replacement within the carnivoran guild.
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Global and regional environmental changes have influenced the evolutionary processes of hominoid primates, particularly during the Miocene. Recently, a new Lufengpithecus cf. lufengensis hominoid fossil with a late Miocene age of ~6.2 Ma was discovered in the Shuitangba (STB) section of the Zhaotong Basin in Yunnan on the southeast margin of the Tibetan Plateau. To understand the relationship between paleoclimate and hominoid evolution, we have studied sedimentary, clay mineralogy and geochemical proxies for the late Miocene STB section (~16 m thick; ca. 6.7–6.0 Ma). Our results show that Lufengpithecus cf. lufengensis lived in a mildly warm and humid climate in a lacustrine or swamp environment. Comparing mid to late Miocene records from hominoid sites in Yunnan, Siwalik in Pakistan, and tropical Africa we find that ecological shifts from forest to grassland in Siwalik are much later than in tropical Africa, consistent with the disappearance of hominoid fossils. However, no significant vegetation changes are found in Yunnan during the late Miocene, which we suggest is the result of uplift of the Tibetan plateau combined with the Asian monsoon geographically and climatically isolating these regions. The resultant warm and humid conditions in southeastern China offered an important refuge for Miocene hominoids.
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The origin of the Old World brevirostrine gomphotheriid taxon Sinomastodon has been debated intensively. The discovery of the oldest known Sinomastodon cranium, reported herein, supports its endemic origin and contradicts the prevalent theory of its North America origin. The new cranium was discovered from the Shuitangba locality, southwestern China, and is dated at about 6.5–6.0 Ma, corresponding to the latest Miocene. The new specimen shows distinct characters from the other species of Sinomastodon and was therefore named Sinomastodon praeintermedius, sp. nov. Newly discovered, isolated Sinomastodon-like teeth from the upper Miocene to the lower Pleistocene of southwestern China and Southeast Asia indicate a long evolution of Sinomastodon endemically. Remains of this species are frequently accompanied by those of stegodontid species. These two groups may have had a similar migration route, invading northern China and Japan during the latest Miocene, and retreating or becoming extinct from the Palearctic realm by the end of the Pliocene. The migrations of proboscideans may have been sparked by major paleoenviromental changes, i.e., the strengthened summer monsoon beginning in the late Miocene (~7–8 Ma) and global cooling due to the expansion of ice sheets from the middle Pliocene to the early Pleistocene. The new finding reveals a close relationship of the early Pliocene fauna of northern China and the latest Miocene fauna of southwestern China, and thus provides novel insight into the origin and components of Pliocene fauna in northern China.
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The fossil tapirid records of Late Miocene and Early Pliocene were quite poor in China as before known. The recent excavations of the terminal Miocene hominoid site (between 6 and 6.5 Ma) at Shuitangba site, Zhaotong in Yunnan Province resulted in the discovery of rich tapir fossils, which include left maxilla with P2-M2 and mandibles with complete lower dentitions. The new fossil materials can be referred to Tapirus yunnanensis, which represents a quite small species of the genus Tapirus. But T. yunnanensis is slightly larger than another Late Miocene species T. hezhengensis from Gansu, northwest China, both of which are remarkably smaller than the Plio-Pleistocene Tapirus species in China. The new fossils provided more information to define the species T. yunnanensis more precisely. Yunnan can be regarded as one of the centers of tapir evolution during the Mid-Late Miocene period, as quite a number of Mid-Late Miocene tapir fossils have been recovered in several localities of Yunnan, which include Xiaolongtan, Yuanmou, Lufeng, Zhaotong and others. Based on the measurements of tooth size, the late Cenozoic tapirs were generally getting larger gradually through time in China, which means the tooth sizes coincide well with their geological ages, the later the larger, and all the Mid-Late Miocene tapirs are exclusively small-sized; thus, the tooth size of fossil tapirs in China is likely to have some significance in age estimation. By contrary, both the dwarf and the normal-sized or larger-sized tapirs were discovered from Mid-Late Miocene strata in Europe and North America.
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Rescue excavations carried out from 2007 to 2010 at the Shuitangba lignite field in Zhaotong, Yunnan Province, not only resulted in the discovery of a new hominoid cranium and the addition of a new hominoid site in Yunnan, but the finding of a new muntjak with following characters: the brow tine is very close to the burr, which is moderately developed; the main beam extends backward and somewhat laterally, and then turns somewhat medially; and the neocrista and entocingulum are developed on the upper molars. The four limbs are relatively short. A cladistic analysis shows that the new materials represent a muntjak that is not in a sister-group relationship with Muntiacus leilaoensis from Yuanmou Late Miocene hominoid site, but rather represents an independent branch. Muntiacus zhaotongensis sp. nov. is proposed for the new muntjak materials. "Metacervulus sp." from the "Yongle lignite field" recovered in 1978 is a synonym of the new species. The so-called "Yongle lignite field" is actually the Shuitangba lignite field. The layers yielding the materials of M. zhaotongensis sp. nov. are all within C3An.1n based on paleomagnetic correlation, with an estimated age between 6.1 to 5.9 Ma (terminal Miocene).
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We describe here a new species of gigantic otter, Enhydriodon dikikae, sp. nov., from the Pliocene of Dikika, in the lower Awash valley of Ethiopia. The holotype consists of an associated snout and mandible, and is the most complete fossil specimen of a large bunodont otter. In some features, such as its very large size, the loss of anterior premolars, the tall protocone of P4, and the divided paraconid of m1, this species illustrates the culmination of general trends in this group, but the most remarkable part of its dentition is the broad incisor arch and powerful canine battery. The purported distinction between Enhydriodon and Sivaonyx is discussed, and the hypothesis of distinct African and Asian lineages is rejected. Postcranial remains confirm that Enhydriodon dikikae, sp. nov., was probably mostly terrestrial, but its diet remains uncertain, as none of the suggested preys fully explains the anatomical adaptations and relative abundance of this species.
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We describe here specimens of the otter Sivaonyx cf. gandakasensis from the late Middle Miocene hominoid-bearing basin of Chiang Muan, northern Thailand. Asian Sivaonyx species were previously recorded in the Late Miocene of the Siwalik Hills and Southern China. The new Thai remains could constitute the oldest occurrence of the genus in Asia (12.4-12.2 m.y.) and, more generally, in the Old World. S. gandakasensis, also occurring in the early Late Miocene and possibly Middle Miocene deposits of the Siwalik Hills, is the most primitive species of the genus. Based on the m1 morphology, we suggest a close relationship of this species with S. hessicus from the Late Miocene of Europe. In this study, we discuss the primitive morphological characters of Eurasian Sivaonyx compared to African ones, using notably the previously unknown M1 of S. cf. gandakasensis (e.g., developed M1 parastyle, high protoconid and narrow talonid basin on m1). Moreover, S. bathygnathus, the third and most derived Eurasian species known from the Late Miocene of the Siwaliks and Southern China, seems to be the most probable ancestor of Mio-Pleistocene African Sivaonyx. We therefore propose a dispersal of Sivaonyx from Asia to Africa during the Late Miocene, probably between ca. 10 and 7 m.y.
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The dental remains of mustelids from two Late Miocene localities of the Teruel Basin are described. Mionictis ginsburgi sp.n. is based on a M1 from the Ademuz locality (NM 12, Middle Turolian), and morphologically most resembles Mionictis dubia Blainville, but is larger in size and with the talon of M1 more antero-posteriorly expanded. In the Late Turolian (NM 13) locality of Las Casiones a M1 and a M1-M2 are determined as Plesiogulo monspessulanus Viret. This species is the largest representative of the genus, and it is the first time that a M1 is described as belonging to this species. -Authors
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Fossil apes are known from several late Miocene localities in Yunnan Province, southwestern China, principally from Shihuiba (Lufeng) and the Yuanmou Basin, and represent three species of Lufengpithecus. They mostly comprise large samples of isolated teeth, but there are also several partial or complete adult crania from Shihuiba and a single juvenile cranium from Yuanmou. Here we describe a new, relatively complete and largely undistorted juvenile cranium from the terminal Miocene locality of Shuitangba, also in Yunnan. It is only the second ape juvenile cranium recovered from the Miocene of Eurasia and it is provisionally assigned to the species present at Shihuiba, Lufengpithecus lufengensis. Lufengpithecus has most often been linked to the extant orangutan, Pongo pygmaeus, but recent studies of the crania from Shihuiba and Yuanmou have demonstrated that this is unlikely. The new cranium reinforces the view that Lufengpithecus represents a distinct, late surviving lineage of large apes in the late Miocene of East Asia that does not appear to be closely affiliated with any extant ape lineage. It substantially increases knowledge of cranial morphology in Lufengpithecus and demonstrates that species of this genus represent a morphologically diverse radiation of apes, which is consistent with the dynamic tectonic and biotic milieu of southwestern China in the late Miocene.
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The giant otter Enhydritherium terraenovae, a New World taxon thought to be related to both the Old World otter Enhydriodon and the extant sea otter Enhydra, was originally described on the basis of relatively limited material, mostly dental. However, an incomplete skeleton of E. terraenovae recovered from the early Hemphillian Moss Acres Racetrack site in northern Florida includes a skull, mandible, part of the axial skeleton, and most of both the fore- and hindlimbs, adding greatly to knowledge of this animal. On the basis of this new material, the osteology of this species is described in detail for the first time, with its diagnosis revised accordingly. This new osteological information, along with information about the nature of the Moss Acres Racetrack site, allows such paleoecological and functional aspects of E. terraenovae as habitat preference, mode of swimming, and diet to be inferred or interpreted in a detail previously impossible. E. terraenovae: 1) was a habitat generalist rather than a marine specialist, as previously thought; 2) was reasonably competent for terrestrial locomotion; 3) extensively used its forelimbs during swimming like living otariid seals, in contrast to the hindlimb-specialized Enhydra; and 4) had a generalized diet, potentially including soft items such as fish, as well as hard items, such as thick-shelled molluscs.
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The phylogenetic relationships of the skunks to the Mustelidae and other caniform carnivores were examined using mitochondrial-DNA (mtDNA) sequence data from portions of the 12S and 16S ribosomal RNA (rRNA) genes. Data were combined with partial sequences of the cytochrome b gene and morphological data obtained from the literature, and used in a total-evidence analysis. The Mustelidae represented a paraphyletic group, with the skunks (Conepatus, Mephitis, and Spilogale) and the Oriental stink badger (Mydaus) forming a monophyletic clade separate from a clade containing the rest of the Mustelidae and the monophyletic Procyonidae. Within the Mustelidae, minus the skunks and stink badger, only one currently recognized subfamily, the Lutrinae, represented a monophyletic group. The families Phocidae, Otariidae, and Odobenidae formed a monophyletic group that was the sister group to the clade composed of the skunks, procyonids, and mustelids. The families Ursidae and Canidae occurred at the base of the Caniformia clade. It is proposed that the skunks be elevated to the level of family and be referred to as the Mephitidae. The family Mephitidae includes the genera Mephitis (striped and hooded skunks), Conepatus (hog-nosed skunks), Spilogale (spotted skunks), and Mydaus (Oriental stink badgers).
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This study presents and attempt of interpretation of the phylogenetical relationships of the Musteloidea (sensuTedford, 1976), especially orientated towards aquatic forms (Lutrinae, Semantoridae, Phocidae). Contrary to the opinion of N. Schmidt Kittler (1981). Potamotherium is classified near the Mustelidae, in part because of the presence of a residual suprameatal fossa in the middle ear of this genus. The Mustelidae, in the traditionnal meaning, represents a paraphyletic grouping and the genera Enhydra and Enhydriodon are tentatively separated from the Lutrinae to constitute the sister group of the Phocidae and Semantoridae. The genera Potamotherium and Semantor are united in Semantoridae, a family which perhaps represents a paraphyletic grouping, taking into account the poor knowledge of Semantor. This interpretation is in agreement with the diphyletism of Pinnipeds which relates the Phocidae to the Mustelidae and the Otariidae to the Ursidae.
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We can follow the regular acquisition of the melin structures from Dehmictis of MN3 to recent Meles and Taxidea through many European Lower Miocene to Pliocene European forms, and also through Upper Miocene Asiatic and Pliocene American ones.
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Northern Thailand comprises more than 40 Tertiary intermontane basins. These basins, tectonically interpreted as grabens or half grabens, have yielded hominoid fossils and rich Neogene mammal faunas. Relative ages provided by biochronological studies are controversial and neither absolute ages nor correlations with marine deposits are available. A precise temporal framework provided by magnetic-polarity stratigraphy is therefore crucial to understand the evolution of these Southeast Asian mammalian faunas, to estimate the timing and duration of basin formation, and finally to allow correlations with other Neogene hominoid localities of the Old World. A complete magnetostratigraphic study, which significantly extends previous paleomagnetic investigations, has been conducted in the Miocene sequence of Mae Moh Basin, Lampang Province, northern Thailand. Based on the biostratigraphic constraints, the 15 polarity zones recognized from the composite section have been correlated with Chrons C5ACr-C5r.3r, between 14.1 and 12.0 Ma. The present study provides a high-resolution magnetostratigraphic reference for the continental middle Miocene of all Southeast Asia. By correlation with the Miocene sequence of the nearby basin of Chiang Muan, the large-bodied hominoid (Khoratpithecus chiangmuanensis)-bearing levels can be precisely dated between 12.4 and 12.2 Ma.
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Fossil remains of Lartetictis (Blainville 1841) from the Middle Miocene (MN 6) of Goldberg are described. Both mandibles, parts of the upper dentition, and parts of the left forelimb and the left hindlimb are preserved. All specimens are coming from the same individual. For the first time, upper and lower teeth can therebe be related to each other. Dentition as well as postcranial remains give strong evidence that the genus belongs to basale musteline mustelids. Paleobiogeographical comparison with the lutrine Paralutra jaegeri shows that, despite their differences in forelimb function, both species compete too much to be sympatrical. Instead, it seems probable that Paralutra replaced Lartetictis as semiaquatical fish-hunter
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A short account is presented here of the discovery of new material attributable to Paralutra garganensis Willemsen, 1983, the only carnivore species documented from the Late Miocene endemic "Terre Rosse" faunal complex (also referred to as the "Mikrotia fauna"). Although thousands of fossil remains of the "Mikrotia fauna" have been collected during extensive sampling campaigns carried out since the 1970's, Paralutra garganensis was to date only represented by the type specimens. The recent revision of material belonging to the "Mikrotia fauna" housed in Museum collections in Firenze and Torino (Italy) and Leiden (Netherlands) has allowed the identification of the specimens described herein and, furthermore, has highlighted new evidence regarding the ecology of the species. The latter findings in turn broaden our understanding to date of the ecological structure of the "Mikrotia fauna".
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The lowest part of the Monarch Mill Formation in the Middlegate basin, west-central Nevada, has yielded a middle Miocene (Barstovian Land Mammal Age) vertebrate assemblage, the Eastgate local fauna. Paleobotanical evidence from nearby, nearly contemporaneous fossil leaf assemblages indicates that the Middle Miocene vegetation in the area was mixed coniferous and hardwood forest and chaparral-sclerophyllous shrubland, and suggests that the area had been uplifted to 2700-2800 m paleoaltitude before dropping later to near its present elevation of 1600 m. Thus, the local fauna provides a rare glimpse at a medium- to high-altitude vertebrate community in the intermountain western interior of North America. The local fauna includes the remains of fish, amphibians, reptiles, birds, and 25 families of mammals. Carnivorans, the focus of this study, include six taxa (three of which are new) belonging to four families. Canidae are represented by the borophagine Tomarctus brevirostris and the canine Leptocyon sp. indet. The earliest record and second North American occurrence of the simocyonine ailurid Actiocyon is represented by A. parverratis sp. nov. Two new mustelids, Brevimalictis chikasha gen. et sp. nov. and Negodiaetictis rugatrulleum gen. et sp. nov., may represent Galictinae but are of uncertain subfamilial and tribal affinity. The fourth family is represented by the felid Pseudaelurus sp. indet. Tomarctus brevirostris is limited biochronologically to the Barstovian land mammal age and thus is consistent with the age indicated by other members of the Eastgate local fauna as well as by indirect tephrochronological dates previously associated with the Monarch Mill Formation. Actiocyon parverratis sp. nov. extends the temporal range of the genus Actiocyon from late Clarendonian back to the Barstovian. The Eastgate local fauna improves our understanding of mammalian successions and evolution, during and subsequent to the Mid-Miocene Climatic Optimum (∼14-17 Ma).
Article
The systematic revision of the European species classified in the Mionictis genus allows us to remove them from this North American genus. Mionictis dubia from the Middle Miocene of Sansan and Goriach is now the type species of Lartetictis n.g. and the recently described Mionictis ginsburgi from the Upper Miocene of Ademuz the type species of Adroverictis, genus that also includes Adroverictis schmidtkittleri, a new species proposed for the Peruniinae indet. from the Middle Miocene of the Yeni Eskihisar.
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A new genus and species of sea otter, Enhydritherium terraenovae is described from Hemphillian deposits of the Withlacoochee 4A site and the Upper Bone Valley Formation, Florida and from the Etchegoin and San Mateo formations, California. Cladistic analysis supports recognition of two lineages of large late Tertiary otters formerly included in the genus Enhydriodon: Enhydritherium (including E. terraenovae) and E. lluecai and Enhydriodon s.s. (including E. sivalensis, E. falconeri and E. africanus). Numerous jaw and dental characters distinguish Enhydritherium from Enhydriodon. E. terraenovae is most closely related to E. lluecai from the Turolian of Spain. The fossil record suggests imigration of Enhydritherium to North America from Eurasia during the late Miocene (7-8 Ma) either along the Pacific side of the Bering Land Bridge or via the North Atlantic. The earliest record of this genus in North America is from the early Hemphillian Withlacoochee 4A site of Florida. The occurrence of E. terraenovae, only in marine rocks or in faunas with at least an estuarine component, indicates that, like the modern sea otter, this species was adapted to coastal marine habitats.-Authors
Article
This chapter analyzes the fossil record of South Asia's Neogene small land mammals in the context of its paleobiogeography. Within the Indian Subcontinent, high faunal similarity can be observed among local small mammal assemblages distributed on a scale of 1000 kilometers, and these are distinct from assemblages to the west and northwest and northeast, beyond the subcontinent. Eastward into Thailand, Myanmar (Burma), and Yunnan, China, faunal similarity with the Indian Subcontinent is apparent but weaker than within the subcontinent. This pattern mimics the distribution of the present-day Oriental biogeographic province. This chapter examines the extent to which this paleozoogeographic pattern can be defined, as well as faunal elements that do not follow the rules. Evidence from Yunnan, Thailand, and Myanmar shows that many genera of small mammals are shared throughout southern Asia.
Chapter
Twenty-four sections in the Yuncu subbasin of the Yushe Basin complex were sampled for magnetostratigraphy. A clear pattern of resolved magnetozones indicates the distinctive pattern of Late Miocene Chron C3An for the oldest part of the sequence, the Mahui Formation. The Gaozhuang Formation is dominantly reversely magnetized and correlated with the Gilbert Chron. The superposed Mazegou Formation represents Gauss Chron, but truncated magnetozones indicate a basal hiatus of about half a million years. These two formations are therefore Pliocene in age. The overlying reversely magnetized Haiyan Formation is correlated with Chron C2r, the early reversed subchron of the Matuyama, Early Pleistocene in age. Four sections in the Tancun subbasin record late Chron C3An and C3r (the latter being early Gilbert Chron). Deposition in both subbasins, near the trunk of the Zhuozhang River, began in the Late Miocene, antedating the commencement of sedimentation in the Zhangcun subbasin. Age control, initially provided by vertebrate fossils, is refined by the magnetostratigraphy, which provides precision for dating the Yushe succession of fossiliferous localities.
Article
Euryale (Nymphaeaceae) is a monotypic genus distributed in eastern Asia, but fossils in its native distribution are sparse as compared to Europe where the genus has disappeared. Here, we describe a new fossil species, Euryale yunnanensis sp. nov., from the late Miocene Zhaotong Basin in southwestern China on the basis of seed remains. Characteristics including an ellipsoidal to almost spherical shape, a smooth surface, a germination cap that covers the micropyle, the separation of the hilum and germination cap (micropyle), elliptic testa surface cells with undulate margins and thickened cell walls collectively indicate a close affinity with the genus Euryale in Nymphaeaceae. Comparisons of seed morphology and anatomy demonstrate that the newly described fossil species differs from modern and other fossil species of Euryale and thus verify the assignment to a new fossil species. As the modern Euryale is an aquatic plant, preferably living in swamps and lakes with shallow and stable water, we hypothesize that a lake and/or swamp environment with shallow water was present near Shuitangba in the Zhaotong Basin, where the Shuitangba hominoid lived during the late Miocene. This inference is generally consistent with paleoenvironmental data extracted from avian, fish, frog, turtle and crocodile fossils, as well as from aquatic pollen. The fossil history suggests a comparatively recent (Miocene) emergence of Euryale, which is roughly in agreement with the divergence time inferred from the molecular information.
Chapter
An Astronomically Tuned Neogene Time Scale (ATNTS2012) is presented, as an update of ATNTS2004 in GTS2004. The new scale is not fundamentally different from its predecessor and the numerical ages are identical or almost so. Astronomical tuning has in principle the potential of generating a stable Neogene time scale as a function of the accuracy of the La2004 astronomical solution used for both scales. Minor problems remain in the tuning of the Lower Miocene. In GTS2012 we will summarize what has been modified or added since the publication of ATNTS2004 for incorporation in its successor, ATNTS2012. Mammal biostratigraphy and its chronology are elaborated, and the regional Neogene stages of the Paratethys and New Zealand are briefy discussed. To keep changes to ATNTS2004 transparent we maintain its subdivision into headings as much as possible.
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— 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.
Article
A new genus and species of otter-like mustelid, Teruelictis riparius, is created on the basis of a partial skeleton from the Late Miocene (Vallesian age, MN 10) locality of La Roma 2 (Teruel, Spain), including several postcranial elements, the skull, and the mandible. The combination of a typically lutrine dentition, similar to that of other fossil otters such as Paralutra jaegeri, with a very slender postcranial skeleton, including a long back and gracile long bones and metacarpals, thus lacking any aquatic adaptations, was previously unknown in the fossil record. This mosaic of features strongly suggests the possibility that the aquatic lifestyle of otters could have appeared after the initial development of the distinctive dental morphology of this specialized group of mustelids.
Article
In this paper, a revision of the Pliocene and Quaternary Lutrinae from Europe is presented. Such a revision, including fossil material, has not been published since the work of Pohle (1919). Three tribes within the Lutrinae are recognized: the Lutrini, the Aonyxini and the Enhydrini. The latter comprises both Enhydra and the Enhydriodon group. The genus Nesolutra, consisting of three insular species, is not retained. Two are included in Lutra and for N. ichnusae a new genus, Sardolutra, is proposed. The genus Isolalutra is not retained either. Its only species, I. cretensis, is included in the genus Lutrogale. Some new material of this species is described. A number of well-preserved fossils of Cyrnaonyx antiqua are described, such as the hitherto unknown skull and upper carnassial as well as postcranial material from Tornewton Cave. The systematic position of the species and genus is reviewed in detail. A new specimen of Enhydra reevei from Bramerton is described. The morphology of the M1 supports the inclusion of the species in Enhydra. The functional morphology and the ecology of the reviewed species is discussed and compared to extant lutrines. Adaptations in the postcranial skeleton indicate a very aquatic way of life for Lutra simplicidens, L. trinacriae, L. euxena and, to an even greater extent, Sardolutra. Lutrogale cretensis on the contrary shows a more terrestrial adaptation. Cyrnaonyx shows adaptations similar to Lutra and probably was a stream dweller, thus differing from its extant relative Aonyx. From the dentition and the endocranial cast, conclusions on the feeding habits are drawn. The described Lutra and Sardolutra species were probably all specialized on motile prey, viz. fish. Lutrogale, Algarolutra, Megalenhydris and Cyrnaonyx show adaptations to a mixed diet, consisting of both fish and shellfish, though differences in the feeding habits between those forms are noted also. Enhydra reevei probably fed on shellfish exclusively. In the last part, the phylogeny and palaeogeography of the Lutrinae are discussed. It is argued that the oldest Lutrinae, Mionictis spp., originated from the Melinae. The phylogeny of the Lutrini can be reconstructed relatively well. The ancestry of the island forms in the Mediterranean is discussed in some detail. For the Aonyxini, the fossil record is rather poor and a reconstruction of the phylogeny is virtually impossible. The origin of Cyrnaonyx is uncertain and the ancestry of Megalenhydris is unknown. The origin of the Enhydrini is somewhat obscure. The group reached a wide distribution and gave rise to the Enhydra line. The relationships between the species are discussed. The problems involved in island species are considered. Remarks on the presence of otters in unbalanced island faunas are made. The peculiar taphonomy of otter fossils on islands is noted.
Article
A new lutrine species, Paralutra garganensis, is described from the Miocene of the Gargano area, Italy. The material consists of a maxillary fragment with P4 and M1 and a calcaneum. There is a clear resemblance with P. jaegeri (Fraas), but the talon of the P4 is larger in the Gargano species. Also, the latter species was larger. It is concluded, that P. jaegeri was ancestral to P. garganensis, and that the latter probably fed on shellfish to a greater extent than the former.
Article
The minerals found in the no. 5 coal (Late Permian) from the Zhaotong Coalfield, Yunnan Province, southwestern China, have been examined and found to consist mainly of kaolinite, pyrite, chamosite, quartz, and calcite, with trace amounts of illite and mixed-layer illite-smectite. The proportion of chamosite in clay minerals ranges from 32 to 56 wt%, with an average of 46 wt%. Chamosite is distributed not only in collodetrinite, but also occurs as cell fillings in fusinite, semifusinite, and telinite. The high content and mode of occurrence of chamosite in this mine indicate its formation by interaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. Except for a minor amount of terrigenous quartz, most quartz is of authigenic origin and formed from kaolinite desilication. The calcite content of the no. 5 coal is 1.4-6.3% (with an average of 3%) and is distributed in collodetrinite and as cell fillings of coal-forming plants. Calcite originated from seawater invasion during peat accumulation. Pyrite occurs in several ways: as massive, framboidal, isolated enhedral/anhedral, and euhedral forms. In addition, the presence of a large amount of pyritized red algae provides strong evidence of seawater invasion during peat accumulation. The red algae may have played an important role in the enrichment of sulfur in the coal. The characteristic assemblage of minerals in this mine resulted from a unique basinal environment in which the mineral matter was derived from a basaltic source region, volcanic activity, and seawater transgression during coal formation.
Article
Foraminifera with an organic, or predominantly organic, test wall ('allogromiids' in the traditional sense) are an important, diverse but often overlooked component of marine benthic communities. This paper reviews some of the scattered literature on these protists. They vary from <50mum to a centimetre or more in length and are morphologically diverse, including spherical, oval, sausage-shaped and thread-like forms. Most are monothalamous and have either one aperture (e.g. Allogromia) or two terminal apertures at either end of the test (e.g. Nemogullmia and Thiogullmia). Some distinctive deep-sea forms (Nodellum, Placopsilinella and Resigella) are polythalamous; the test consists of more or less well-defined chambers and the wall is brownish in colour. Organic-walled allogromiids are reported from marine habitats ranging from supralittoral sands and intertidal mudflats to deep-sea trenches and are particularly abundant and diverse in cold, tranquil settings with fine-grained sediments (e.g. the deep sea, fjords, and some polar environments). Relatively few morphospecies have been formally described, and most of these are from coastal and intertidal settings, yet these delicate foraminifera often account for 10-20% of individuals and morphospecies in deep-sea samples. At Arctic coastal sites influenced by turbid glacial meltwater, and in some estuaries, allogromiids (including saccamminids) represent an even higher proportion of live foraminifera, in some cases >90%. In contrast, organic-walled allogromiids and other monothalamous forms are usually relatively uncommon in dysoxic settings. Experimental and field studies support the idea that, in a general sense, allogromiids are less tolerant of oxygen depletion than the calcareous taxa that usually dominate foraminiferal faunas in low-oxygen habitats. Organic-walled allogromiids occupy, a variety of microhabitats. Intertidal and sublittoral species have been described from the sheltered interiors of empty polychaete tubes and large foraminiferal tests. Some species are associated with the sediment-water interface while others occur at different depths within the sediment. Very elongate, thread-like morphotypes often live several centimeters below the sediment surface in bathyal and abyssal settings. The ecological role of organic-walled aliogromiids is poorly known. In general, they seem to be less responsive to inputs of fresh organic matter than calcareous foraminifera. Indirect evidence suggests that many deep-sea species, particularly forms with two terminal apertures, consume bacteria.
Article
The phylogenetic relationship of the 13 extant species of otters were analyzed by canonical variate analysis using mensural data and by Wagner analysis using qualitative characters. The results of the two analyses showed a high degree of concordance. The information of the generalized distance (D) and Wagner trees was combined in an Adams-2 consensus tree. The phylogenetic hypothesis generated deviates from currently accepted classifications chiefly in separating the species of river otters of the genus Lutra, as it is generally conceived, into two groups of genera. One, the New World river otters (Lontra), is a monophyletic group phylogenetically linked to the African and Asian clawless otters (Aonyx and Amblonyx). The other group, their Old World ecological counterparts (Lutra), constitutes a different clade. Enhydra and Pteronura are the most divergent of living otters, the former being closer to the clawless otters and the latter to the smooth-coated otter (Lutrogale), which in turn is phylogenetically close to the Old World river otters (Lutra). Available independent evidence, although incomplete, does not contradict the hypothesis.
Article
Otters are classified in the Lutrinae and are united by a suite of semi-aquatic adaptations that distinguish them from the rest of the Mustelidae. Past systematic studies have been based primarily on overall similarity of morphological characters but have not been concordant, with regard either to relationships within the subfamily or to the relationships of the Lutrinae to other taxa in the Mustelidae. We evaluate the relationships among nine of the 13 species of otters and their position in the Mustelidae through phylogenetic analysis of the complete nucleotide sequence of the mitochondrial cytochrome b gene. Based on the sequence data presented here, our results suggest that otters are divided into three primary clades that include: (1) the North American river, neotropical and marine otters; (2) the sea, Eurasian, spotted-necked, cape clawless and small-clawed otters; and (3) the giant otter. Furthermore, our results indicate that among sampled mustelid taxa, members of the genus Mustela are most closely related to otters. The hierarchical relationships among clades are not well resolved, particularly the monophyly of otters, largely because a pattern of short internal branches combined with long terminal branches suggests a rapid evolutionary radiation. Estimates of divergence time calibrated by the fossil record suggest that the lineages leading to the North American river, neotropical and marine otters, and the giant otter diverged before the end of the Miocene, much earlier than predicted from the fossil record.