Bernard Marandat

A new orang-utan relative from the Late Miocene of Thailand

The fossil record of the living great apes is poor. New fossils from undocumented areas, particularly the equatorial forested habitats of extant hominoids, are therefore crucial for understanding their origins and evolution. Two main competing hypotheses have been proposed for orang-utan origins: dental similarities support an origin from Lufengpithecus, a South Chinese and Thai Middle Miocene hominoid; facial and palatal similarities support an origin from Sivapithecus, a Miocene hominoid from the Siwaliks of Indo-Pakistan. However, materials other than teeth and faces do not support these hypotheses. Here we describe the lower jaw of a new hominoid from the Late Miocene of Thailand, Khoratpithecus piriyai gen. et sp. nov., which shares unique derived characters with orang-utans and supports a hypothesis of closer relationships with orang-utans than other known Miocene hominoids. It can therefore be considered as the closest known relative of orang-utans. Ancestors of this great ape were therefore evolving in Thailand under tropical conditions similar to those of today, in contrast with Southern China and Pakistan, where temperate or more seasonal climates appeared during the Late Miocene.

Late middle Eocene epoch of Libya yields earliest known radiation of African anthropoids

Reconstructing the early evolutionary history of anthropoid primates is hindered by a lack of consensus on both the timing and biogeography of anthropoid origins. Some prefer an ancient (Cretaceous) origin for anthropoids in Africa or some other Gondwanan landmass, whereas others advocate a more recent (early Cenozoic) origin for anthropoids in Asia, with subsequent dispersal of one or more early anthropoid taxa to Africa. The oldest undoubted African anthropoid primates described so far are three species of the parapithecid Biretia from the late middle Eocene Bir El Ater locality of Algeria and the late Eocene BQ-2 site in the Fayum region of northern Egypt. Here we report the discovery of the oldest known diverse assemblage of African anthropoids from the late middle Eocene Dur At-Talah escarpment in central Libya. The primate assemblage from Dur At-Talah includes diminutive species pertaining to three higher-level anthropoid clades (Afrotarsiidae, Parapithecidae and Oligopithecidae) as well as a small species of the early strepsirhine primate Karanisia. The high taxonomic diversity of anthropoids at Dur At-Talah indicates either a much longer interval of anthropoid evolution in Africa than is currently documented in the fossil record or the nearly synchronous colonization of Africa by multiple anthropoid clades at some time during the middle Eocene epoch.

The anthropoid status of a primate from the late middle Eocene Pondaung Formation (Central Myanmar): Tarsal evidence

Primate dental and postcranial remains from the Eocene Pondaung Formation (Myanmar) have been the subject of considerable confusion since their initial discoveries, and their anthropoid status has been widely debated. We report here a well preserved primate talus discovered in the Segyauk locality near Mogaung that displays derived anatomical features typical of haplorhines, notably anthropoids, and lacks strepsirhine synapomorphies. Linear discriminant and parsimony analyses indicate that the talus from Myanmar is more similar structurally to those of living and extinct anthropoids than to those of adapiforms, and its overall osteological characteristics further point to arboreal quadrupedalism. Regressions of talar dimensions versus body mass in living primates indicate that this foot bone might have belonged to Amphipithecus. This evidence supports hypotheses favoring anthropoid affinities for the large-bodied primates from Pondaung and runs contrary to the hypothesis that Pondaungia and Amphipithecus are strepsirhine adapiforms.

Late Middle Eocene primate from Myanmar and the initial anthropoid colonization of Africa

Reconstructing the origin and early evolutionary history of anthropoid primates (monkeys, apes, and humans) is a current focus of paleoprimatology. Although earlier hypotheses frequently supported an African origin for anthropoids, recent discoveries of older and phylogenetically more basal fossils in China and Myanmar indicate that the group originated in Asia. Given the Oligocene-Recent history of African anthropoids, the colonization of Africa by early anthropoids hailing from Asia was a decisive event in primate evolution. However, the fossil record has so far failed to constrain the nature and timing of this pivotal event. Here we describe a fossil primate from the late middle Eocene Pondaung Formation of Myanmar, Afrasia djijidae gen. et sp. nov., that is remarkably similar to, yet dentally more primitive than, the roughly contemporaneous North African anthropoid Afrotarsius. Phylogenetic analysis suggests that Afrasia and Afrotarsius are sister taxa within a basal anthropoid clade designated as the infraorder Eosimiiformes. Current knowledge of eosimiiform relationships and their distribution through space and time suggests that members of this clade dispersed from Asia to Africa sometime during the middle Eocene, shortly before their first appearance in the African fossil record. Crown anthropoids and their nearest fossil relatives do not appear to be specially related to Afrotarsius, suggesting one or more additional episodes of dispersal from Asia to Africa. Hystricognathous rodents, anthracotheres, and possibly other Asian mammal groups seem to have colonized Africa at roughly the same time or shortly after anthropoids gained their first toehold there.

A new primate from the Eocene Pondaung Formation of Myanmar and the monophyly of Burmese amphipithecids

The family Amphipithecidae is one of the two fossil primate taxa from Asia that appear to be early members of the anthropoid clade. Ganlea megacanina, gen. et sp. nov., is a new amphipithecid from the late middle Eocene Pondaung Formation of central Myanmar. The holotype of Ganlea is distinctive in having a relatively enormous lower canine showing heavy apical wear, indicating an important functional role of the lower canine in food preparation and ingestion. A phylogenetic analysis of amphipithecid relationships suggests that Ganlea is the sister taxon of Myanmarpithecus, a relatively small-bodied taxon that has often, but not always, been included in Amphipithecidae. Pondaungia is the sister taxon of the Ganlea + Myanmarpithecus clade. All three Pondaung amphipithecid genera are monophyletic with respect to Siamopithecus, which is the most basal amphipithecid currently known. The inclusion of Myanmarpithecus in Amphipithecidae diminishes the likelihood that amphipithecids are specially related to adapiform primates. Extremely heavy apical wear has been documented on the lower canines of all three genera of Burmese amphipithecids. This distinctive wear pattern suggests that Burmese amphipithecids were an endemic radiation of hard object feeders that may have been ecological analogues of living New World pitheciin monkeys.

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.

New Sivaladapid primates from the Eocene Pondaung formation of Myanmar and the Anthropoid status of Amphipithecidae

Abstract Fossil primates from the late middle Eocene Pondaung Formation of Myanmar have figured prominently in recent efforts to reconstruct the early evolutionary history of anthropoids. The anthropoid affinities of Amphipithecidae, the most abundant fossil primates currently known from the Pondaung Formation, have proven to be particularly controversial. Here we describe two new genera and species, Paukkaungia parva and Kyitchaungia takaii, of sivaladapid primates from the Pondaung Formation. Tarsal elements that are appropriate in size and morphology to belong to Kyitchaungia takaii are also described. These are the first undoubted adapiforms—and the first fossil primates other than anthropoids—to be reported from the Eocene of Myanmar. The discovery of sivaladapids in the Pondaung Formation enhances the taxonomic and paleoecological diversity of the late middle Eocene primate fauna of Myanmar. In this respect, the fossil primate community from the Pondaung Formation appears to have resembled roughly contemporaneous assemblages from China, Thailand, and Pakistan. The newly discovered sivaladapid tarsal elements help to resolve conflicting interpretations regarding the taxonomic allocation of large-bodied primate postcranial elements from the Pondaung Formation. The NMMP 20 partial skeleton from the Pondaung Formation, which has often been regarded as that of an amphipithecid, is more plausibly interpreted as pertaining to a third Pondaung sivaladapid. Recognizing the sivaladapid affinities of the NMMP 20 partial skeleton solidifies the anthropoid status of amphipithecids, further constraining temporal, phylogenetic, and biogeographic hypotheses regarding anthropoid origins.

NEW REMAINS OF PONDAUNGIMYS ANOMALUROPSIS (RODENTIA, ANOMALUROIDEA) FROM THE LATEST MIDDLE EOCENE PONDAUNG FORMATION OF CENTRAL MYANMAR

Abstract Except for the few specimens previously reported from the late middle Eocene of North Africa (Algeria) and more recently from South Asia (Myanmar), the fossil record of anomaluroid rodents is relatively scarce for the Paleogene Period. In this paper, we describe new material, notably a skull, of the anomaluroid taxon Pondaungimys anomaluropsis Dawson et al., 2003, recently described from the latest middle Eocene Pondaung Formation in Central Myanmar (South Asia). Pondaungimys shows a dental pattern very similar to that of Nementchamys, an anomaluroid rodent previously reported from roughly coeval deposits in Algeria. Although Nementchamys and Pondaungimys have a dental pattern relatively more primitive in some respects than that of Miocene and modern anomalurids, in other respects they show a derived dental complexity that leads us to consider both taxa as the closest outgroups of the Anomaluridae sensu stricto (the true scaly-tailed flying squirrels) within the Anomaluroidea. Pondaungimys clearly demonstrates that the evolutionary history of the anomaluroid rodents is not limited to Africa. The widespread South Asian-North African distribution of the late middle Eocene forms strongly suggests that faunal exchanges between Africa and Asia took place during the Paleogene, a statement supported by other mammalian groups.

Talar Morphology, Phylogenetic Affinities, and Locomotor Adaptation of a Large-Bodied Amphipithecid Primate From the Late Middle Eocene of Myanmar

A well-preserved fossil talus [National Museum of Myanmar Primates (NMMP) 82] of a large-bodied primate is described from the late middle Eocene Pondaung Formation of central Myanmar. The specimen was collected at Thandaung Kyitchaung, a well-known amphipithecid primate-bearing locality near the village of Mogaung. NMMP 82 adds to a meager but growing sample of postcranial remains documenting the large-bodied primates of the Pondaung Formation. This new talus exhibits a suite of features that resemble conditions found in living and fossil haplorhine primates, notably anthropoids. As such, the phylogenetic signal deriving from the morphology of NMMP 82 conflicts with that provided by NMMP 20, a partial skeleton (including a fragmentary calcaneus) of a second large-bodied Pondaung primate showing undoubted adapiform affinities. Analysis subtalar joint compatibility in a hypothetical NMMP 82/NMMP 20 combination (talus/calcaneus) reveals a substantial degree of functional mismatch between these two tarsal bones. The functional incongruence in subtalar joint morphology between NMMP 20 and NMMP 82 is consistent with the seemingly divergent phylogenetic affinities of these specimens, indicating that two higher level taxa of relatively large-bodied primates are documented in the Pondaung Formation. On the basis of its size and morphology, we refer the NMMP 82 talus to the large-bodied amphipithecid Pondaungia. The occurrence of anthropoid-like tali in the Pondaung Formation obviates the need to invoke homoplasy to explain the shared, derived dental characters that are common to amphipithecids and undoubted anthropoids. Functionally, the NMMP 82 talus appears to have pertained to a primate that is engaged in active quadrupedalism in an arboreal environment along broad and subhorizontal branches. The primate taxon represented by NMMP 82 was capable of climbing and leaping, although it was not particularly specialized for either of these activities.

First Middle Miocene Rodents from the Mae Moh Basin (Thailand): Biochronological and Paleoenvironmental Implications

Abstract We report here the first discovery of microvertebrates from the Mae Moh coal mine, Lamphang Province, northern Thailand. This discovery sheds new light on the age and paleoenvironments of the Miocene basins of northern Thailand. Previous investigations of paleomagnetic stratigraphy in the Mah Moh Basin demonstrated that the fossiliferous Q and K coal seams there date between 13.12–13.3 Ma. The microvertebrate fauna from the Q and K coal seams includes Tarsius sp., erinaceid insectivores and rodents, the last being represented by the monospecific genera Prokanisamys and Neocometes. These microvertebrate fossils are extremely similar to elements of the Mae Long fauna from the Li Basin, which had been estimated to date between 16–18 Ma. Accordingly, the Mae Long fauna in the Li Basin appears to be contemporaneous with the fauna from the Q and K coal seams in the Mae Moh Basin, suggesting that previous estimates of the age of the Mae Long fauna were 3–5 Ma too old. The discovery of numerous fragments of the primitive deer Stephanocemas cf. rucha and the pig Conohyus thailandicus in the Mae Moh Basin confirms the correlation suggested by the microvertebrates. As a result, there is no longer any reason to advocate a west-east chronological gradient for the opening of the intermontane basins of northern Thailand. Alternatively, dating of other Tertiary basins in Thailand suggests a south-north gradient. The Krabi Basin, located in peninsular Thailand, is of latest Eocene age, the Nong Ya Plong Basin in central Thailand dates to the late Oligocene, and basins in northern Thailand are middle Miocene in age. Analysis of mammalian faunas and pollen indicate that the middle Miocene was a period of dramatic climatic fluctuations in northern Thailand. The Q and K coal seams in the Mae Moh Basin show a temperate-tropical vegetation, whereas the uppermost coal layers testify to warmer tropical vegetation. Based on magnetostratigraphic data, these climatic fluctuations were synchronous with those observed in Antarctic deep waters. Climatic fluctuations during the middle Miocene cannot be used for purposes of correlation, because they appear to have occurred in an iterative fashion.