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The iconic sabretooth Homotherium is thought to have hunted cooperatively, but the origin of this behaviour and correlated morphological adaptations are largely unexplored. Here we report the most primitive species of Amphimachairodus ( Amphimachairodus hezhengensis sp. nov.), a member of Machairodontini basal to Homotherium , from the Linxia Basin, northeastern border of the Tibetan Plateau (9.8–8.7 Ma). The long snout, laterally oriented and posteriorly located orbit of Amphimachairodus suggest a better ability to observe the surrounding environment, rather than targeting single prey, pointing to an adaptation to the open environment or social behaviour. A pathological forepaw of Amphimachairodus provides direct evidence of partner care. Our analyses of trait evolutionary rates support that traits correlated with killing behaviour and open environment adaptation evolved prior to other traits, suggesting that changes in hunting behaviour may be the major evolutionary driver in the early evolution of the lineage. A. hezhengensis represents one of the most important transitions in the evolution of Machairodontini, leading to adaptation in open environments and contributing to their further dispersal and radiation worldwide. This rapid morphological change is likely to be correlated with increasingly arid environments caused by the rise of the Tibetan Plateau, and competition from abundant large carnivores in this area.

The Yuanmou hominid site is a rare Late Miocene fossil locality in southern China, where thousands of fossil specimens of the ape Lufengpithecus hudiensis have been found. These have been well studied, but the taxonomy of other mammalian groups is not fully understood. This is especially the case for large predator Felidae, which play a key role in the palaeo-environment in which these fossil apes lived. Here we study the systematics of fossil Felidae from Yuanmou, which is composed of four species of machairodonts: Amphimachairodus cf. horribilis, Longchuansmilus xingyongi gen. & sp. nov., aff. Yoshi sp., Machairodontinae gen. & sp. indet. and one species of feline, Felinae gen. & sp. indet. Longchuansmilus xingyongi is a member of Machairodontini, related to Lokotunjailurus and possibly two derived species of Paramachaerodus, i.e. P. orientalis and P. maximiliani. The high diversity of machairodonts suggests a unique palaeo-environment of the Yuanmou Basin during the Late Miocene, different from northern Eurasia or modern south-eastern Asia. An analysis of body size and intraguild competition suggests that aff. Yoshi sp. and Machairodontinae gen. & sp. indet. are probably regular predators of the fossil great ape, which may have pushed the high evolutionary rate of the fossil ape.

Jiangzuo, Qigao, Flynn, John J., Wang, Shiqi, Hou, Sukuan, Deng, Tao (2023): New Fossil Giant Panda Relatives (Ailuropodinae, Ursidae): A Basal Lineage of Gigantic Mio-Pliocene Cursorial Carnivores. American Museum Novitates 2023 (3996): 1-72, DOI: 10.1206/3996.1, URL: https://bioone.org/journals/american-museum-novitates/volume-2023/issue-3996/3996.1/New-Fossil-Giant-Panda-Relatives-Ailuropodinae-Ursidae--A-Basal/10.1206/3996.1.full

We name a rare, hypercarnivorous and durophagous mustelid Sonitictis moralesi, new genus and species, in honour of Jorge Morales for his contributions to carnivore palaeontology. Sonitictis morales...

The age when the giant panda (Ailuropoda melanoleuca) transitioned to a bamboo dominant diet has not been well established due to the lack of fossil evidence. In particular, a radial sesamoid bone,...

The fossil records of large amphicyonids in Asia are rare and fragmentary, and their evolution and dispersal are also unclear. Here we present new dental material from Laogou, Linxia Basin, Gansu P...

Martes is one of the most widely spread genera and probably has the longest evolutionary history among the living Carnivora, yet its fossil record is incomplete, especially those related to the crown group of Martes. Here we describe a fossil species, Martes crassidens sp. nov. from the Jinyuan Cave, Luotuo Hill, Dalian Puwan Economic Zone, Liaoning Province in northeastern China. The materials were found from the lower deposits belonging to the early-middle Early Pleistocene. Our morphological comparison, morphometric and morphotype analyses suggest the fossil species shows a clear affinity to the Holarctic marten group (here referred to HMG), i.e. Martes martes, Martes zibellina, Martes melampus, Martes americana, in having robust dentition, enlarged P4 protocone and M1 inner lobe. It also has unique characters, e.g. relatively large body size, very robust carnassial, high crowned m1 and relatively short talonid, which is different from any living and known fossil species and probably suggests a durophagous dietary behavior. Martes crassidens represents so far the earliest record of the HMG, and provides evidence for the chronological framework of the crown marten diversification.

The origin of Elasmotherium has been a puzzle for many years. Herein, we report the earliest representative of Elasmotherium, based on a Late Miocene skull from Dingbian County in Shaanxi, northwes...

Recently, rich fossiliferous deposits dated to the late Cenozoic have been discovered from Jinyuan Cave at Luotuo Hill, an extremely large-sized cave site situated within in the Dalian Puwan Economic Zone of Dalian Municipality, Liaoning Province in Northeast China. Abundant and diverse vertebrate fossils unearthed from different fossiliferous layers of Jinyuan Cave, a site of enormous size with a sedimentary thickness of over 40 m and its deposits can be roughly divided into three fossiliferous deposit units, altogether containing six fossiliferous layers belonging to different ages from the Late Pliocene to the Middle Pleistocene. Based on a combination of biostratigraphic and geochronological evidence, the fossil assemblages from Jinyuan Cave can be divided into three successive faunas that span the Late Cenozoic (ca. 3.60–0.35 Ma): the Wanghai fauna from upper faunal unit (Middle Pleistocene, 0.78–0.35 Ma), the Jinyuan fauna from middle-lower faunal unit (Early Pleistocene, 2.60–0.78 Ma) and the Luotuoshan fauna of the bottommost faunal unit (Late Pliocene, 3.6–2.6 Ma). The mammalian faunal evolution of Jinyuan Cave can be divided into four temporal stages during the late Cenozoic. The new discovered Jinyuan Cave provides a unique and nearly-continuous faunal and sedimentary sequence stretching from the Late Pliocene to the Middle Pleistocene, hugely significant for establishing the Quaternary Mammal Fauna Sequence of Northeast China for the first time based on a combination of biostratigraphy, geochronology, and for discussing the environmental background.

The giant short-faced hyena, Pachycrocuta brevirostris, was the largest and most spectacular bone-cracking hyena that ever existed. Although already extinct long ago, it was extensively distributed across Eurasia during the Early and Middle Pleistocene. P. brevirostris is remarkable for a series of iconic craniodental adaptations in sway with a commitment to scavenging off carcasses of other large herbivores, such as the powerfully built skull and massive premolars, yet the most eye-catching aspect is the enormous size as emphasized by its vernacular name. The largest hitherto known skull of this species is the holotype from Sainzelles in Auvergne, France, discovered over a century ago. We hereby report a new discovery from Jinyuan Cave in Dalian, China, which slightly surpasses the holotype in craniodental dimension, posing a new record in Pachycrocuta body size. Three skull fragments of the same individual unearthed from the site are described in detail herein and compared with other P. brevirostris discoveries from both Europe and Asia. Thorough comparative studies show that the newly discovered materials are very close to the holotype from Sainzelles both metrically and morphologically, which fully indicates that the European morphotype, namely Pachycrocuta brevirostris brevirostris, surprisingly appeared in Northeast Asia as well, and further challenges the conventional concept of the population or subspecies. The giant hyenas from Asia were originally proposed as independent species, such as Pachycrocuta licenti or P. sinensis, but now broadly accepted as conspecifics of the European Pachycrocuta brevirostris, forming only different subspecies. The occurrence of P. b. brevirostris in Northeast Asia forcefully demonstrates that the differentiation is more of temporal than geographical significance, i.e., the subspecies of Eurasia basically constituted an ancestor-descendant sequence, from licenti to sinensis via brevirostris. Moreover, represented by the newly discovered specimens, the forerunner of P. b. brevirostris with transitional features appeared in Northeast Asia as early as 2.0 Ma, which implies the population of Europe most likely originated and dispersed from Northeast Asia. A hypothesis of “out of Northeast Asia” is hereby proposed for P. b. brevirostris. In the present paper, a series of diagnostic craniodental characters, such as carnassial morphology, the accessory cuspids of the premolars and the shape of the skull profile, are also discussed and re-valuated to investigate their potential significance in phylogenetic analysis.

The sabertoothed cat Megantereon is an iconic carnivore in the Pleistocene of Eurasia, yet its fossil record is extremely rare and highly fragmentary in southern China (and the whole Oriental Realm...

With advances in molecular phylogeny, the Ursidae affinity of Ailuropoda is no longer controversial. However, the early evolution of Ailuropoda and its close relatives (the tribe Ailuropodini) is still unclear. In this study, we describe a new fossil discovery from Bulgaria, which represents a new taxon of Ailuropodini, ?Agriarctos nikolovi. The materials of Ailurarctos are restudied and the evolution and dispersal of Ailuropodini are discussed. Early Ailuropodini split into two lineages, one in Europe as Agriarctos (three species, whose assignment to the same genus is not certain), and one in southeastern Asia as Ailurarctos and later Ailuropoda. Ailurarctos is a paraphyletic group, with both known species as successive direct ancestors to Ailuropoda. Subtribe Ailuropodina is proposed here to include Ailurarctos and Ailuropoda. Turolian European Agriarctos paralleled with Ailuropodina in many aspects, which reflects similar adaptation towards a specific herbivorous diet.

Lufengpithecus keiyuanensis from the Xiaolongtan Coal Mine is the earliest known Miocene fossil hominoids in southern China, yet its chronological context has long been subjected to disputes, in being either of late Middle Miocene or early Late Miocene age. This controversy is largely due to the uncertainty of the exact positions of previously discovered fossils in the outcrops, and the different chronological interpretations for some proboscidean and suid fossils from associated fossil faunal assemblages. Here we report the first discovery of Stegolophodon latidens from Xiaolongtan with an unambiguous stratigraphic provenance, which provides important evidence in constraining the age of Lufengpithecus keiyuanensis . Stegolophodon has a very high evolutionary rate of dental morphology, and exhibits a pronounced evolutionary trend with time: from the pentalophodont m3 of the Early Miocene or early Middle Miocene, to the pentalophodont M3 and hexalophodont m3 of the late Middle Miocene, to the 5.5-lophed (five principal lophs followed by an extreme well-developed cingulum) M3 and hexa- to heptalophodont m3 of the early Late Miocene, and to the hexalophodont M3 and hepta- to octalophodont m3 of the middle Late Miocene. The newly discovered Stegolophodon latidens bears a 5.5-lophed M3 and a heptalophodont m3, the second and subsequent lophs/lophids show a slight chevron structure, and the pretrite mesoconelets shift mesially and fuse with the corresponding pretrite anterior central conules, forming a “Y-shape”. These traits are similar to, or even slightly more derived than those of Stegolophodon from the lower part of the Dhok Pathan Formation (9.3−8.3 Ma) in the Middle Siwaliks of the Indian Subcontinent. The materials described here can all be assigned to Stegolophodon latidens which was originally discovered from the Yenangyaung fauna, the lower Irrawaddy Formation of Myanmar, deemed of early Late Miocene age. Revisions on the other proboscidean and suid materials also support an early Late Miocene age for Xiaolongtan Fauna. The new fossils were discovered from the upper part of the lignite layers, close to the bottom of the greyish marls of the Buzhaoba Formation. Based on the original records in the geological reports of the Xiaolongtan Coal Mine, the descriptions of the previous publications, as well as the accounts of the fossil finders, the Xiaolongtan coal mine possesses only one fossiliferous layer, which locates in the upper part on the Xiaolongtan Formation (lignite layers). Therefore, the new fossils situate possibly in the same layer as Lufengpithecus keiyuanensis that were found in the 1950’s and 1980’s. From the recent palaeomagnetic investigations, the age of this fossil layer should be 11.6/11.7 Ma, close to the boundary between the Middle and the late Miocene; however, seems to be slightly older than Stegolophodon latidens from the Siwaliks. Further investigations should be carried out to resolve this inconsistency.

Felids from G.E. Lewis’ Yale Peabody Museum collection of Siwalik fossil mammals are described, and palaeobiogeography is interpreted based on these specimens. Five felid taxa are recognised from t...

The construction of morphological character matrices is central to paleontological systematic study, which extracts paleontological information from fossils. Although the word information has been repeatedly mentioned in a wide array of paleontological systematic studies, its meaning has rarely been clarified nor specifically defined. It is important, however, to establish a standard to measure paleontological information because fossils are hardly complete, rendering the recognition of homologous and homoplastic structures difficult. Here, based on information theory, we show the deep connections between paleontological systematic study and communication system engineering. Information is defined as the decrease of uncertainty and it is the information in morphological characters that allows distinguishing operational taxonomic units (OTUs) and reconstructing evolutionary history. We propose that concepts in communication system engineering such as source coding and channel coding, correspond to the construction of diagnostic features and the entire character matrices in paleontological studies. The two coding strategies should be distinguished following typical communication system engineering, because they serve dual purposes. With character matrices from six different vertebrate groups, we analyzed their information properties including source entropy, mutual information, and channel capacity. Estimation of channel capacity shows character saturation of all matrices in transmitting paleontological information, indicating that, due to the presence of noise, oversampling characters not only increases the burden in character scoring, but also may decrease quality of matrices. We further test the use of information entropy, which measures how informative a variable is, as a character weighting criterion in parsimony‐based systematic studies. The results show high consistency with existing knowledge with both good resolution and interpretability., Resembling a communication system, the fundamental problem of paleontological studies is reconstructing at present either exactly or approximately organisms living in another age. Information theory provides a new perspective in paleontological systematic studies.

A new troodontid (LH PV39) recovered from the Upper Cretaceous Wulansuhai Formation, Inner Mongolia, China, is described, highlighting the dorsoventrally compressed sacral centra. The completely fused neurocentral junctions indicate that LH PV39 had reached adulthood at the time of death, but its size is nevertheless 20% smaller than that of the sympatric Philovenator, demonstrating that it is the second small-bodied troodontid recovered from the Wulansuhai Formation. Phylogenetic analyses scoring LH PV39 using different strategies and performed with different algorithms unambiguously recovered it as a troodontid. While the parsimony-based analysis scoring LH PV39 as an independent OTU with all of its available characteristics included recovered it as a basal troodontid, the Bayesian analysis suggests a closer relationship of LH PV39 to Almas and an unnamed troodontid from Ukhaa Tolgod, Mongolia (MPC-D100/1126+D100/3500). Body size analysis confirmed a single trend of gigantism throughout the evolution of troodontids, and suggests that the Late Cretaceous troodontids evolved in two directions: (i) several size-independent characteristics evolved while retaining the small sizes that are typical of the Early Cretaceous relatives, resulting in the Late Cretaceous small-bodied troodontids; and (ii) size-dependent characteristics (e.g., the elongation of the rostrum) evolved accompanying the size increase, resulting in large-bodied derived troodontids. The mosaic features of the Late Cretaceous small-bodied troodontids place them intermediate between their Early Cretaceous basal relatives and the Late Cretaceous large-bodied taxa in a well-resolved phylogeny, which is crucial for understanding the size and morphological evolution of troodontids.

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 de...

The tribe Lyncodontini (Mammalia, Carnivora, Mustelidae) was widely distributed in Eurasia during the Plio-Pleistocene. In East Asia, only Eirictis and Oriensictis are known so far. Herein, we describe a new complete cranium of Lyncodontini from Layer 2 of Jinyuan cave of Luotuo Hill, Puwan area of Dalian, Liaoning Province in Northeast China and undertake detailed comparisons with related taxa. The specimen is similar to Oriensictis, especially Oriensictis melina in Locality 1 of Zhoukoudian in tooth morphology and represents the same species of the latter, but the cranial characters are strikingly similar to those of Enhydrictis galictoides from Sardinia. We therefore relegate Oriensictis to a subgenus of Enhydrictis as East Asian members of the clade in the Middle Pleistocene, whereas the subgenus Enhydrictis is endemic to Sardinia. The craniodental characters of E. melina are more derived than those of E. galictoides in many aspects, so it is unlikely to be a direct ancestor to E. galictoides. The Early Pleistocene Martellictis ardea from Saint Vallier probably represents the ancestor group of this genus. This clade immigrated along the Paratethys during the Late Villafranchian. Part of this metapopulation probably dispersed into East Asia during the late Early Pleistocene or early Middle Pleistocene along with other carnivores (e.g. Xenocyon sp. and Panthera youngi) during interglacial period, whereas others dispersed back to Europe during the Middle Pleistocene, as represented by the Sardinia population. The E. melina from Layer 2 of Luotuo Hill is morphologically more derived than the Middle Pleistocene E. nipponica from Japan, thus the age of Layer 2 is possibly not older than Middle Pleistocene.

For a long time, it is controversial whether cave bears have ever lived in China during the Pleistocene. Here we checked the published and unpublished bear fossils from Zhoukoudian (North China) housed in Institute of Vertebrate Paleontology and Palaeoanthropology, CAS and Zhoukoudian Site Museum, and compared them with contemporary cave bears and brown bears. Our observation confirms the existence of cave bears only in Loc. 1 of Zhoukoudian. The general morphology of cave bears in China is similar to that of the early Middle Pleistocene cave bears in Europe and this bear can be assigned to Ursus deningeri. The metacarpals of U. deningeri from Loc. 1 of Zhoukoudian are much plumper than those of the approximately contemporary U. deningeri from Hundsheim (Austria) and are similar to those of the Late Pleistocene U. spelaeus/ingressus, presumably with a good digging ability. In contrast to Europe and Caucasus, cave bears from China are much less abundant than brown bears during the Middle Pleistocene.

Summary In Carnivora, increases in body size often lead to dietary specialization toward hypercarnivory. Ursine bears (Tremarctos and Ursus), however, are the only omnivorous Carnivora that evolved large body sizes (i.e., >50 kg). Traits contributing to their gigantism, and how those traits evolved, have never been studied. Here we propose that special dental characters of Ursinae (parallel buccal and lingual ridges) permit a sagittally oriented mastication associated with increasing emphasis on plant foods. This pattern can be traced back to a new early diverging bear of plant-dominated omnivorous diet, Aurorarctos tirawa gen. et sp. nov. from the late Middle Miocene of North America, which was supported as the earliest known ursine bear by phylogenetic analysis. The anatomical transition to increased masticatory efficiency, probably together with the ability to hibernate, helped bears break prior ecological limitations on body size and led to the evolution of a distinctive lineage of herbivorous-omnivorous, large-bodied Carnivora., Graphical Abstract, Highlights • We describe the earliest known ursine bear, supported by phylogenetic analyses • The new fossil bear has the earliest evidence of plant-dominated omnivory diet • We discuss how traits helped ursine bears breaking energetic limitations on body size, Biological Sciences; Evolutionary Biology; Phylogenetics

Canis mosbachensis is a widely distributed species from the Early to Middle Pleistocene in Europe. In Eastern Asia, Canis variabilis was supposed to be a local subspecies of C. mosbachensis, but such hypothesis has never been tested in details. Here we restudied the Canis materials from type locality, Loc.1 of ZKD (Zhoukoudian) of Middle Pleistocene, as well as other localities that produced important materials of this taxon (e.g. Loc.13 of ZKD). To better evaluate the variability of the Pleistocene Canis, a series of morphotypes are described. Based on morphotype and morphometric, the present study reveals there is only one species present at Loc.1 and Loc.13 of ZKD, which is quite similar to European C. mosbachensis and should be revised as a subspecies of C. mosbachensis, namely C. mosbachensis variabilis. C. m. variabilis is more derived and less hypercarnivorous than the Early Pleistocene Canis chihliensis (as well as European Canis etruscus and Canis arnensis) in craniodental characters, whereas it is less derived and less hypercarnivorous than Canis lupus. A review of fossil records of C. m. variabilis in China was made based on these different characters. Canids from Gongwangling, Lantian of Shaanxi Province (middle or late Early Pleistocene) are the earliest known representatives of C. mosbachensis in China, which are still more primitive than C. m. variabilis from the Middle Pleistocene sites of ZKD. Reliable records of C. mosbachensis are only known from the Early Pleistocene to the late Middle Pleistocene in Northern China. C. m. variabilis is not direct ancestor to C. lupus but a close relative of the latter, while it is far from the Early Pleistocene C. chihliensis. The latter remains more primitive characters that are more similar to those of European Canis etruscus and Canis arnensis.

“Arctonyx” fossil remains from the Liucheng Gigantopithecus Cave, Guangxi, are redescribed and analysed in details. Detailed tooth character differences between Arctonyx and Meles are analysed. It is shown that materials from the Liucheng Gigantopithecus Cave actually belong to two species of Meles: Meles minor and Meles magnus n. sp. At the same time, a review of Late Pliocene and Early Pleistocene Meles records in China is made. During Late Pliocene, Meles are only represented by M. chiai and one archaic form. During Early Pleistocene, Meles from northern and central part of China are represented by two nearly sympatric species Meles chiai and Meles teihardi. Meles from South China are represented by M. minor and M. magnus n. sp., though the distribution of the two species is still unclear. M. magnus n. sp. is so far only known from the Liucheng Gigantopithecus Cave, whereas M. minor is probably also known from Longgupo, Chongqing in the central part of China besides Liucheng. Great diversity of Meles in Early Pleistocene in China indicates that the genus radiated earlier than previously thought. Phylogenetic analysis suggests M. magnus n. sp. is sister group to living M. leucurus, whereas M. minor and M. chiai are early branches in Meles evolution.

Amphicyonidae is one of the most widely distributed families of Carnivora in the Early and Middle Miocene, yet the fossil record of this family is extremely poor in Eastern Asia. In this study, we ...

A central premise of bioclimatic envelope modeling is the assumption of niche conservatism. Whereas such assumptions are testable in modern populations, it is unclear whether niche conservatism holds over deeper time spans and over very large geographic ranges. Hyaenids occupied a diversity of ecological niches over time and space, and until the end-Pleistocene they occurred in Europe and most of Asia, with Asian populations of Crocuta suggested as being genetically distinct from their closest living relatives. Further, little is known regarding whether and how the dietary ecology of extinct populations of Crocuta differed from those of their extant African counterparts. Here, we use a multiproxy approach to assess an assumption of conserved dietary ecology in late Pleistocene extant spotted hyenas via finite element analysis, dental microwear texture analysis, and a novel dental macrowear method (i.e., whether teeth are minimally, moderately, or extremely worn, as defined by degree of dentin exposure) proposed here. Results from finite element simulations of the masticatory apparatus of Chinese and African Crocuta demonstrate lower skull stiffness and higher stress in the orbital region of the former when biting with carnassial teeth, suggesting that Chinese Crocuta could not process prey with the same degree of efficiency as extant Crocuta crocuta. Dental microwear texture data further support this interpretation, as Chinese Crocuta have intermediate and indistinguishable complexity values (indicative of hard-object feeding) between the extant African lion (Panthera leo) and extant hyenas (C. crocuta, Hyaena hyaena, and Parahyaena brunnea), being most similar to the omnivorous P. brunnea. The use of dental macrowear to infer dietary behavior may also be possible in extinct taxa, as evinced by dietary correlations between extant African feliforms and dental macrowear assignments. Collectively, this multiproxy analysis suggests that Chinese Crocuta may have exhibited dietary behavior distinct from that of living C. crocuta, and assumptions of niche conservatism may mask significant dietary variation in species broadly distributed in time and space.

Bears are a group of carnivores with diverse diets and complicated dental structure. Several large rearrangements of dental structures are known in different lineages of bears, making the homology of dental structures between the different bears difficult to evaluate. By tracing the evolutionary processes of the two lineages of bears with the most complicated dental structure, i.e., the giant panda lineage (Ailuropodinae) and cave bear lineage (Ursinae), we were able to clarify the homology of dental structures of the two subfamilies. We define a new assemblage of dental nomenclature (based mainly on the homology to the giant panda) that can be very useful to infer the evolution of fossil bears. The evolutionary positions of some fossil bears are reviewed based on our results.