A new Late Eocene primate from the Krabi Basin (Thailand) and the diversity of Palaeogene anthropoids in southeast Asia

According to the most recent discoveries from the Middle Eocene of Myanmar and China, anthropoid primates originated in Asia rather than in Africa, as was previously considered. But the Asian Palaeogene anthropoid community remains poorly known and inadequately sampled, being represented only from China, Myanmar, Pakistan and Thailand. Asian Eocene anthropoids can be divided into two distinct groups, the stem group eosimiiforms and the possible crown group amphipithecids, but the phylogenetic relationships between these two groups are not well understood. Therefore, it is critical to understand their evolutionary history and relationships by finding additional fossil taxa. Here, we describe a new small-sized fossil anthropoid primate from the Late Eocene Krabi locality in Thailand, Krabia minuta, which shares several derived characters with the amphipithecids. It displays several unique dental characters, such as extreme bunodonty and reduced trigon surface area, that have never been observed in other Eocene Asian anthropoids. These features indicate that morphological adaptations were more diversified among amphipithecids than was previously expected, and raises the problem of the phylogenetic relations between the crown anthropoids and their stem group eosimiiforms, on one side, and the modern anthropoids, on the other side.     

Oligocene sivaladapid primate from the Bugti Hills (Balochistan, Pakistan) bridges the gap between Eocene and Miocene adapiform communities in Southern Asia

A new species of Guangxilemur (Sivaladapidae, Adapiformes) is described from the early Oligocene Chitarwata Formation (Bugti Member) of the Bugti Hills, Sulaiman geological Province, Balochistan, Pakistan. Guangxilemur singsilai n. sp. provides further diagnostic morphological characters from its newly described upper and lower dentitions, confirming its intermediate phylogenetic position between Eocene and Miocene Asian sivaladapid adapiforms. G. singsilai possesses moderately developed shearing and puncturing molar features and maintains lingual cusps on upper molars as in Eocene hoanghoniines; in contrast, it possesses a typical molariform P(4) as in Miocene sivaladapines. The important paleogeographic changes that have affected South Asia during the Tertiary (related to the collision between the Indian and Eurasian Plates) have played a critical role in reforming circulation and climatic differentiation. The presence in Pakistan of an unique and well-diversified Oligocene primate fauna, clearly demonstrates that South Asia maintained favourable environmental conditions during the middle Caenozoic global climatic deterioration that coincides with drastic changes in faunal structure on the whole Holarctic Province, including the extinction of adapiform primates.     

The westernmost tarsier: A new genus and species from the Miocene of Pakistan

As the closest living sister group of anthropoids, tarsiers (Family Tarsiidae) are an important group in primate evolution. However, their fossil record is poor: only four species have been described, two from the Eocene of China and two from the Miocene of Thailand. All are from outside the range of the living species, which occur only on islands off Southeast Asia. Here, we describe a new fossil tarsier from Pakistan, a significant range extension. This record consists of two lower molars, an upper molar, and a lower premolar found in the Miocene Manchar Formation (∼18–16 Ma [millions of years ago]) of Sindh Province, southern Pakistan. The Pakistani tarsier is morphologically distinct from all living and fossil tarsiers, but most similar to the middle Miocene Thai species Tarsius thailandicus. Though living tarsiers have traditionally been classified in a single genus, a recent revision proposed a division into three genera, which is strongly supported by molecular data. The Pakistani species is not referable to any of these genera, and we create for it and T. thailandicus a new tarsiid genus. This discovery broadens our understanding of the geographic range and morphological diversity of Miocene tarsiers and helps to put the living tarsiers into their evolutionary context.     

亚洲土著类群硅藻鼠科的演化

硅藻鼠科是仅分布于亚洲的啮齿类类群,头骨具豪猪型咬肌结构,下颌则为松鼠型。该类群代表了一个从梳趾鼠类分化出的区域性支系,虽与豪猪次目相近,但并不是它的成员。最早的硅藻鼠化石记录发现于Baluchistan渐新世陆相地层中,稍晚的记录发现于南业晚渐新世。印度次大陆连续的地层为该科的演化历史提供了主要的化石依据。早中新世晚期至中中新世,硅藻科化石也发现了泰国、中国以及日本。其后的硅藻鼠种类少且鲜有化石记录。晚中新世早期在巴基斯坦有一个种,中国南部晚中新世也可能有一个种。尽管在最早的化石地点发现的标本较多,但其后的时段内除泰国李盆地外化石并不丰富,这指示了其特殊的生活习性或其生活区域化石保存的偏差。已知的化石记录并没有指示出该类群的多样性,也可能是缺少石化作用的结果。硅藻鼠类在水系外围区域延续生存与最近在老挝中部多岩石地带发现的现生Laonastes也是一个硅藻鼠的假设相一致。     

A revision of fossil Rhizomyid rodents from Northern India and their correlation to a Rhizomyid biochronology of Pakistan

Based on the biochronology of rhizomyid rodents of Northern Pakistan, fossil horizons in the Siwaliks of Northern India can be correlated to the late Neogene sequence of Pakistan with greater precision than previously possible. The indian Siwaliks do not include records of the most primitive Rhizomyidae, but rhizomyid faunas of India display strong affinity with those of Pakistan in the late Miocene. Pliocene differentiation of rhizomyid faunas in India and Pakistan may reflect ecological partitioning within the Indian subcontinent. Use of the term «Nagri for deposits at Haritalyangar suggests an erroneous equivalence in age to the Nagri stratotype in Pakistan.     

First record of Entelodontidae (Mammalia,Artiodactyla) from the late Eocene of Southeast Asia

We describe two entelodontid upper premolars that were recovered from the late Eocene of the Krabi coal mine in southern Thailand. The size and morphology of the material suggest that it can be referred to Entelodon aff. E. gobiensis, a species known from the late Eocene to the early Oligocene of northern Asia and southern China. The Thai material documents for the first time the southernmost occurrence of entelodontids in Asia during the Paleogene and also suggests that Eocene Southeast Asian mammal localities might potentially yield further entelodontid remains mostly associated with selenodont ungulates.     

Dietary reconstruction of the Amphipithecidae (Primates, Anthropoidea) from the Paleogene of South Asia and paleoecological implications

The primate family, Amphipithecidae, lived during the early Cenozoic in South Asia. In this study, the diet of late middle Eocene amphipithecids from the Pondaung Formation (Central Myanmar) is characterized using three different approaches: body mass estimation, shearing quotient quantification and dental microwear analysis. Our results are compared with other Paleogene amphipithecids from Thailand and Pakistan, and to the other members of the primate community from the Pondaung Formation. Our results indicate a majority of frugivores within this primate community. Pondaungia and “Amphipithecus” included hard objects, such as seeds and nuts, in their diet. Folivory is secondary for these taxa. Myanmarpithecus probably had a mixed diet based on fruit and leaves. Contrasting results and a unique dental morphology distinguish Ganlea from other amphipithecids. These render interpretation difficult but nevertheless indicate a diet tending towards leaves and fruit. However, the anterior dentition of Ganlea suggests that this taxon engaged in seed predation, using its protruding canine as a tool to husk hard fruits and obtain the soft seeds inside. Bahinia and Paukkaungia, two other Pondaung primates, are small (<500 g) and therefore would have depended on insects as their source of protein. As such, they occupied a very different ecological niche from Pondaung amphipithecids. This primate community is then compared with the Eocene-Oligocene primate communities of the Fayum from North Africa. Similarities between the late middle Eocene Pondaung primate community and extant equatorial and tropical South American primate communities are noted.     

First fossil fruits of Elaeocarpus (Elaeocarpaceae) in East Asia: Implications for phytogeography and paleoecology

The genus Elaeocarpus contains approximately 360 species and occurs in mesic forest communities from India, through to China, Southeast Asia, New Guinea, Australia, and New Caledonia. Elaeocarpus fossils are best known from the Eocene to the Miocene of Australia and the late Pliocene–early Pleistocene of India, but have not been documented from East Asia before. Here we describe six new species of Elaeocarpus, E. nanningensis sp. nov. from the late Oligocene Yongning Formation of the Nanning Basin, E. presikkimensis sp. nov. from the Miocene Erzitang Formation of the Guiping Basin, E. prerugosus sp. nov., E. prelacunosus sp. nov., E. preserratus sp. nov., and E. preprunifolioides sp. nov. from the late Miocene Foluo Formation of the Nankang Basin in Guangxi, South China. This is the first reliable report for the genus occurring in East Asia, and the fossils indicate that Elaeocarpus had colonized this region by the late Oligocene and represented by a morphologically diverse group of species by the late Miocene. This sheds new insights into the timing and migration patterns of the genus in East Asia. Elaeocarpus is typically a rainforest genus occurring in mesic forests. Based on the habitat of their morphologically similar modern relatives we propose that these three sedimentary basins were warm and wet adjacent to mountainous regions with the evergreen or rain forests during the late Oligocene to Miocene.     

An omomyid primate from the Pontide microcontinent of north-central Anatolia: Implications for sweepstakes dispersal of terrestrial mammals during the Eocene

A new genus and species of omomyid primate is described from the middle Eocene (Lutetian) Lülük Member of the Uzunçarşidere Formation, Orhaniye Basin, north-central Anatolia, Turkey. This is the first Eocene primate to be reported from the vast area between Switzerland and Pakistan. The new taxon is currently represented by a single dentary fragment, limiting the scope of morphological comparisons that can be made with related taxa. Nevertheless, its dentition differs fundamentally from that of contemporary European microchoerids. The new taxon most closely resembles North American middle Eocene omomyines such as Mytonius hopsoni, and it is therefore interpreted as a member of the Asian/North American omomyine radiation. Its occurrence on the Pontide microcontinent must have resulted from sweepstakes dispersal across the intervening Tethyan barrier that separated the Pontides from adjacent parts of Eurasia during the Lutetian. Sweepstakes dispersal by various terrestrial mammal clades, especially rodents and primates, was facilitated by Eocene greenhouse climatic conditions, which promoted extreme precipitation events and frequent flooding of major river drainages.     

Enamel microstructure defines a major Paleogene hippopotamoid clade: the Merycopotamini (Cetartiodactyla,Hippopotamoidea)

We present new material of the selenodont anthracothere Hemimeryx blanfordi from the Oligocene deposits of the Bugti Hills (Balochistan, Pakistan), collected between 1999 and 2002. This is the first undisputed Oligocene occurrence of the species, previously known from the early Miocene of Pakistan. Investigation of the molar enamel microstructure reveals a surprising mono-zonal Schmelzmuster, already detected in some middle to Late miocene selenedont anthracotheres. We include this observation combined with a morphological revision of H. blanfordi and a cladistic assessment of the dental evidence, to propose a new phylogenetic hypothesis regarding Hemimeryx and its close relatives. We confirm the clade including advanced bothriodontines, which we erect to a tribe rank and name Merycopotamini. The South Asian origin of Merycopotamini is consistent with hypothesized subsequent dispersal events of Merycopotamini from Asia to Africa.     

陕西蓝田晚中新世灞河组沙鼠类化石

沙鼠是一类由早中新世米古仓鼠类 (myocricetodontines)演化而来的啮齿动物 ,现生的种类主要分布于非洲、阿拉伯半岛和亚洲干旱的沙漠—荒漠草原地区。其高阶元的系统分类尚未取得一致的意见 ,但古生物学者一般认为 ,沙鼠类动物自成一科 ,并可分为 3个亚科 :米古仓鼠亚科 (Myocricetodontinae)、裸尾沙鼠亚科 (Taterillinae)和沙鼠亚科 (Gerbillinae) (Jaeger,1 977;Tong ,1 989;Chalineetal.,1 977;Wessels,1 999)。我国的现生沙鼠共有 3属 7种 ,均属Gerbillinae亚科 ,主要分布于蒙新高原及其南邻地带(王应祥 ,2 0 0 3)。最早的化石记录是甘肃泉头沟中中新世的Mellalomysgansus和Myocricetodonplebius (邱铸鼎 ,2 0 0 1 )。在其他新近纪地点发现的有甘肃庆阳、瓦窑堡和灵台 ,山西榆社和内蒙古化德、高德格的Pseudomerionesabbreviatus (Teilhard ,1 92 6;Young ,1 92 7;Schaub ,1 934;李传夔 ,1 981 ;Fahlbuschetal.,1 983;郑绍华、张兆群 ,2 0 0 0 ;QiuandStorch ,2 0 0 0 ;李强等 ,2 0 0 3) ,以及甘肃宁县的Pseudomerionescomplicidens (张兆群 ,1 999)。Mellalomys和Myocricetodon属归入Myocricetodontinae,而Pseudomeriones属归入Gerbillinae。本文记述Myocricetodon和Abudhabia两属沙鼠 ,后者被归     

New strepsirrhine primate from the late Eocene of Peninsular Thailand (Krabi Basin)

In this paper, we describe the newly discovered lower jaw of a primate from the late Eocene Krabi coal mine (Bang Mark pit) of Peninsular Thailand. We performed microtomographic examinations at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) to analyze different morphological aspects of the jaw and teeth. Although partially preserved, this fossil mandible reveals a set of distinctive dental traits (e.g., double-rooted P(2) and molarized P(4)) that allow us to describe a new stepsirrhine adapiform: Muangthanhinius siami, new genus and species. This taxon is somewhat atypical among Paleogene adapiforms, and more specialized than the sivaladapid adapiforms (hoanghoniines) that existed in Asia in the same epoch. In fact, Muangthanhinius shows a degree of dental specialization approximating that of some modern strepsirrhine lemuriforms, although it lacks the highly specialized anterior dentition characterizing this living primate group (canine + incisors forming a very procumbent toothcomb). In contrast, Muangthanhinius exhibits a large canine deeply anchored within the dentary that probably protruded high above the toothrow. Finally, despite the development of a molarized P(4) as in Miocene sivaladapid sivaladapines, Muangthanhinius differs in molar morphology from this group, and the position of this new taxon within the Adapiformes remains indeterminate. Clarification of its phylogenetic position will require more morphological evidence than is currently available.     

New chiropterans from the middle Eocene of Shanghuang (Jiangsu Province,Coastal China): new insight into the dawn horseshoe bats (Rhinolophidae) in Asia

Until recently, the fossil record of Paleogene bats in Asia primarily included extinct families (i.e. ‘Eochiroptera’) from the early Eocene of Vastan in India and from the middle‐late Eocene of the Liguanqiao and Yuanqu basins in central China. Here, we describe a new fauna of Chiroptera from the middle Eocene Shanghuang fissure fillings of China. The fauna includes abundant material referred to a new rhinolophid (Protorhinolophus shanghuangensis gen. and sp. n.), one specimen of a possible rhinopomatid and several indeterminate rhinolophoids. This new bat assemblage constitutes the earliest record of extant families of microbats in Asia. Because it lacks representatives of ‘Eochiroptera’, this Shanghuang bat fauna indicates significant turnover in Asian bat communities. The dental pattern of P. shanghuangensis shows a mosaic of primitive and derived features (‘Eochiroptera’ vs Rhinolophidae dental characteristics), suggesting that this taxon occupies a basal position among the Rhinolophidae. Rhinolophids were already well diversified at the end of the late Eocene in Europe. Interestingly, many dental characteristics of Protorhinolophus are also found in a primitive rhinolophoid taxon, Vaylatsia, from the middle Eocene to late Oligocene of Europe, supporting a close relationship between these taxa. These affinities testify to the widespread Eurasian distribution of rhinolophoids during the Eocene and are consistent with a westward dispersal of the group from eastern Asia to Europe owing to the greater antiquity of Protorhinolophus.     

Diets of fossil primates from the Fayum Depression of Egypt: a quantitative analysis of molar shearing

Over the last 90 years, Eocene and Oligocene aged sediments in the Fayum Depression of Egypt have yielded at least 17 genera of fossil primates. However, of this diverse sample the diets of only four early Oligocene anthropoid genera have been previously studied using quantitative methods. Here we present dietary assessments for 11 additional Fayum primate genera based on the analysis of body mass and molar shearing crest development. These studies reveal that all late Eocene Fayum anthropoids were probably frugivorous despite marked subfamilial differences in dental morphology. By contrast, late Eocene Fayum prosimians demonstrated remarkable dietary diversity, including specialized insectivory (Anchomomys), generalized frugivory (Plesiopithecus), frugivory+insectivory (Wadilemur), and strict folivory (Aframonius). This evidence that sympatric prosimians and early anthropoids jointly occupied frugivorous niches during the late Eocene reinforces the hypothesis that changes in diet did not form the primary ecological impetus for the origin of the Anthropoidea. Early Oligocene Fayum localities differ from late Eocene Fayum localities in lacking large-bodied frugivorous and folivorous prosimians, and may document the first appearance of primate communities with trophic structures like those of extant primate communities in continental Africa. A similar change in primate community structure during the Eocene-Oligocene transition is not evident in the Asian fossil record. Putative large anthropoids from the Eocene of Asia, such as Amphipithecus mogaungensis, Pondaungia cotteri, and Siamopithecus eocaenus, share with early Oligocene Fayum anthropoids derived features of molar anatomy related to an emphasis on crushing and grinding during mastication. However, these dental specializations are not seen in late Eocene Fayum anthropoids that are broadly ancestral to the later-occurring anthropoids of the Fayum's upper sequence. This lack of resemblance to undisputed Eocene African anthropoids suggests that the "progressive" anthropoid-like dental features of some large-bodied Eocene Asian primates may be the result of dietary convergence rather than close phyletic affinity with the Anthropoidea.     

A new species of the genus Microbunodon (Anthracotheriidae, Artiodactyla) from the Miocene of Pakistan: genus revision, phylogenetic relationships and palaeobiogeography

Lihoreau, F., Blondel, C., Barry, J. & Brunet, M. (2004). A new species of the genus Microbunodon (Anthracotheriidae, Artiodactyla) from the Miocene of Pakistan: genus revision, phylogenetic relationships and palaeobiogeography. — Zoologica Scripta , 33 , 97–115.
New unpublished remains of small Anthracotheriinae are described. First, materials from the upper Oligocene (MP 30) locality of La Milloque, southwest France, permit a review of the species Microbunodon minimum . Thereafter, fossils from the middle and late Miocene of the Potwar Plateau, Pakistan are attributed to the European genus Microbunodon . Microbunodon milaensis sp. n. from the Nagri Formation (between 10.3 and 9.2 Ma), Pakistan, is described and the species M. silistrensis from the Lower Manchar Formation (between 16 and 15 Ma) and from the Chinji Formation (between 12.7 and 11.5 Ma), Pakistan, is reviewed. The new species represents the last occurrence of the subfamily Anthracotheriinae, around 9.3 Ma. Similar materials from the Bugti and Siwalik Hills were previously considered as a small Anthracotherium . Comparisons with M. minimum from the European late Oligocene lead to a complete revision of the genus and permit definition of a new set of characters, which separate Microbunodon from Anthracotherium . A cladistic analysis reconsiders phylogenetic relationships among Anthracotheriinae, separating an Anthracothema–Anthracotherium clade and an Anthracokeryx–Microbunodon clade. Microbunodon appears to stem from the Asian late Eocene–lower Oligocene genus Anthracokeryx . These results imply a new distribution of the genus Microbunodon showing exchanges between Europe and Asia during the late Oligocene and probably the lower Miocene.     

ANATOMICAL REVISION OF THE GENUS MERYCOPOTAMUS (ARTIODACTYLA; ANTHRACOTHERIIDAE): ITS SIGNIFICANCE FOR LATE MIOCENE MAMMAL DISPERSAL IN ASIA

Abstract:  New fossil remains of the anthracothere genus Merycopotamus Falconer and Cautley, are described. Most of them were discovered by the Harvard University and Geological Survey of Pakistan joint research project (Y-GSP) in the well-dated Middle and Late Miocene deposits of the Potwar Plateau in northern Pakistan. This new material led us to revise the systematics of the genus with the validation of three species, M. nanus Falconer ( M. pusillus Lydekker), M. dissimilis Falconer and Cautley, and M. medioximus Lihoreau et al. , and allowed us to determine precisely their chronological distributions in a continuous Neogene sequence. Other specimens reported from the late Miocene deposits of the Khorat Plateau in north-east Thailand by the Department of Mineral Resources are the first remains of Merycopotamus to have been discovered in that region and are attributed to M. medioximus . These discoveries indicate a wider geographical distribution of the genus in the early Late Miocene. Anatomical investigations highlight the evolution of Merycopotamus through the Miocene towards more amphibious habits. Palaeobiogeographical and palaeoecological information for Merycopotamus stress the role of the Himalayan orogenesis as a dispersal barrier and the impact of a major global regression event on the evolution of Indian Subcontinent faunas from the Middle Miocene to the Late Pliocene.     

Cynocephalid dermopterans from the Palaeogene of South Asia (Thailand, Myanmar and Pakistan): systematic, evolutionary and palaeobiogeographic implications

Cynocephalid dermopterans (flying lemurs) are represented by only two living genera (Cynocephalus and Galeopterus), which inhabit tropical rainforests of South‐East Asia. Despite their very poor diversity and their limited distribution, dermopterans play a critical role in higher‐level eutherian phylogeny inasmuch as they represent together with Scandentia (tree‐shrew) the sister group of the Primates clade (Plesiadapiformes + Euprimates). However, unlike primates, for which the fossil record extends back to the early Palaeogene on all Holarctic continents and in Africa, the evolutionary history of the order Dermoptera sensu stricto (Cynocephalidae) has so far remained undocumented, with the exception of a badly preserved fragment of mandible from the late Eocene of Thailand (Dermotherium major). In this paper, we described newly discovered fossil dermopterans (essentially dental remains) from different regions of South Asia (Thailand, Myanmar, and Pakistan) ranging from the late middle Eocene to the late Oligocene. We performed microtomographic examinations at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) to analyse different morphological aspects of the fossilized jaws. The abundant material from the late Oligocene of Thailand (Nong Ya Plong coal mine) allows us to emend the diagnosis of the genus Dermotherium and to describe a new species: Dermotherium chimaera sp. n. This species exhibits an interesting mosaic of plesiomorphic cynocephalid characters shared with Cynocephalus and Galeopterus, and as such, it probably documents a form close to the ancestral morphotype from which the two extant forms are derived (supported by cladistic assessment of the dental evidence). The discovery of Palaeogene cynocephalids is particularly significant since it attests to the great antiquity of the order Dermoptera in Asia, and besides, it provides the first spatio‐temporal glimpse into the evolutionary history of that enigmatic mammal group. In that respect, these fossils testify to a long history of endemism in South Asia for dermopterans, and demonstrate that their modern geographic restriction in south‐eastern Asia is clearly a relictual distribution. Cynocephalids had a more widespread distribution during the Palaeogene, which extended from the Indian subcontinent (the rafting Greater India) to South‐East Asia. Their subsequent extinction on the Indian subcontinent was probably mediated by the major palaeogeographic and geomorphologic events related to the India‐Eurasia collision (retreat of the Paratethys Sea, formation of orogenic highlands) that have strongly affected the climate of South Asia at the end of the Oligocene.     

First partial cranium of Togocetus from Kpogamé (Togo) and the protocetid diversity in the Togolese phosphate basin

Earliest cetaceans (whales) originated from the early Eocene of Indo-Pakistan, but the group dispersed through most of the oceans of the planet by the late middle to late Eocene. This late Eocene global distribution indicates that important dispersal events took place during the middle Eocene (Lutetian), a globally undersampled time interval that is well documented in the Togolese phosphate series. We report here the first discovery of a partial cetacean cranium from middle Eocene deposits of Togo (West Africa). A 3D model of the cranium and teeth was reconstructed in order to reveal hidden anatomical features. The dental and cranial characteristics of the Togolese specimen recall those of protocetid taxa described in Africa, Asia, and North America, but also display significant differences. In particular, we show that the new specimen shares a number of morphological features with the Togolese taxon Togocetus. Such a hypothesis is further supported by a cladistic analysis including 45 taxa and 167 morphological characters, which recovers the new specimen close to Togocetus as the first offshoot of protocetids. Phylogenetic analysis including all the protocetids remains of Kpogamé confirms the singular diversity of the Togolese phosphate basin, and enables to examine potential connections with faunas from contemporaneous localities in Africa.