A new Chalicothere from the Pondaung Formation (late Middle Eocene of Myanmar)

The 2002 field work campaign of the joint Myanmar–French Expedition has resulted in the discovery of new material particularly in the Bahin area (Pondaung Formation, Middle–Upper Eocene, Myanmar). The Nyaung Pin Le outcrop has yielded, among other fossil mammals, a maxillary of a primitive chalicothere, the first ever discovered in the southeastern Asia Palaeogene, which is assigned to the Eomoropidae, Eomoropus pawnyunti nov. sp. This form is distinguished from the other representatives of the family by its small size, its brachyodonty and the few derived shape of the molar ectolophs, nevertheless provided with low mesostyles. To cite this article: J.-A. Remy et al., C. R. Palevol 4 (2005).     

Proximal femoral anatomy of a sivaladapid primate from the late middle Eocene Pondaung formation (central Myanmar)

The postcranial anatomy of the Asian sivaladapid adapiforms is still virtually undocumented, whereas dental remains of these primates have been known for several decades. Little is known about their positional behavior as a result. In this article, we describe a partial left femur of a medium-sized primate preserving its entire proximal portion and a significant length of its shaft. This fossil was recently recovered from the fossiliferous locality of Thamingyauk in the late middle Eocene Pondaung Formation (central Myanmar). This femur is considered to pertain to the same individual as two tarsal elements (fragmentary talus and calcaneus) from the same locality (same location), and attributed to a medium-sized sivaladapid adapiform primate (Kyitchaungia takaii). This new postcranial element provides the first documentation of femoral anatomy among Sivaladapidae from Asia. The mechanical implications deriving from the musculoskeletal interpretation of this bone indicate an animal that probably engaged in a kind of active arboreal quadrupedalism with some degree of proficiency in leaping. Even though many musculoskeletal aspects suggest that branch walking and running were important parts of its locomotor repertoire, in other details it appears that relatively complex movements at the hip joint were actually possible and probably associated with climbing or some hindlimb suspensory activities.     

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.     

Anatomy of the bony pelvis of a relatively large-bodied strepsirrhine primate from the late middle Eocene Pondaung Formation (central Myanmar)

Recent survey of the fossiliferous variegated mudstones of the PK1 locality (Sabapondaung) in the late middle Eocene Pondaung Formation (central Myanmar) has led to the recovery of a partial right innominate of a relatively large-bodied primate. Given its size and provenance, this bone probably belongs to the same individual represented by the NMMP 20 primate partial skeleton described previously from the same locality. The new fossil, which preserves the region around the acetabulum and the adjacent part of the ilium, clearly exhibits strepsirrhine rather than anthropoid affinities. This addition to our knowledge of the NMMP 20 partial skeleton allows us to reassess the different locomotor interpretations that have been proposed for this specimen. Aspects of pelvic morphology suggest that the NMMP 20 partial skeleton documents a primate that probably engaged in active arboreal quadrupedalism similar to that practiced by medium-sized Malagasy lemurids rather than lorislike slow moving and climbing. Given the conflicting phylogenetic signals provided by NMMP 39 (a talus showing anthropoid affinities) and NMMP 20 (a partial skeleton bearing adapiform affinities), it appears that two higher-level taxonomic groups of relatively large-bodied primates are documented in the Pondaung Formation. The recent discovery of two taxa of sivaladapid adapiforms from the Pondaung Formation indicates that the assumption that the NMMP 20 partial skeleton belongs to an amphipithecid can no longer be sustained. Instead, this specimen apparently documents a third large-bodied sivaladapid species in the Pondaung Formation.     

Taxonomic status of purported primate frontal bones from the Eocene Pondaung Formation of Myanmar

Two isolated cranial fragments from the late middle Eocene Pondaung Formation of central Myanmar have previously been interpreted as frontal bones of the amphipithecid primate Amphipithecus mogaungensis. Aside from a few maxillary fragments, these specimens provide the only potential source of information currently available regarding the cranial anatomy of Amphipithecidae. Were this taxonomic attribution correct, these specimens would indicate that amphipithecids retained numerous primitive skull features, including the absence of a postorbital septum, the retention of a voluminous olfactory chamber, and strong separation between the forebrain and the orbital fossa. However, several anatomical details observable on these specimens are incompatible with their attribution to any primate and strongly suggest that they cannot be ascribed to Mammalia. Particularly problematic in this regard are the extreme thickness of the dermal bone, the odd structure of the alleged "frontal trigon," and the mediolateral orientation and uniquely robust construction of the descending process of the frontal bone (which partially segregates the orbital and temporal fossae). Because these isolated elements can no longer be attributed to Amphipithecus, the anatomical, phylogenetic, and behavioral inferences regarding amphipithecid paleobiology that have been drawn from these specimens can no longer be sustained.     

A new basal tapiromorph (Perissodactyla, Mammalia) from the middle Eocene of Myanmar

A new genus and species of tapiromorph, Skopaiolophus burmese nov. gen., nov. sp., is described from the middle Eocene Pondaung Formation in central Myanmar. This small form displays a striking selenolophodont morphology associated with a mixture of primitive “condylarthran” dental characters and derived tapiromorph features. Skopaiolophus is here tentatively referred to a group of Asian tapiromorphs unknown so far. The occurrence of such a form in Pondaung suggests that primitive tapiromorphs might have persisted in southeast Asia until the late middle Eocene while they became extinct elsewhere in both Eurasia and North America.     

Sedimentary facies of the late Middle Eocene Pondaung Formation (central Myanmar) and the palaeoenvironments of its Anthropoid Primates

The primate-bearing Pondaung Formation (northwestern part of central Myanmar) is mainly composed of cyclic sequences of sandstones and variegated clays that are divisible into 12 lithofacies and are grouped under seven facies associations. These established facies associations represent the deposition in a fluvio-deltaic environment. The anthropoid primate remains occur in swale-fill sediments, sometimes in carbonate nodules of pedogenetic origin and also, in small crevasse channel deposits of the upper part of the Pondaung Formation. The sedimentary facies associated to these anthropoid primates contribute to the understanding of their morpho-anatomic features. To cite this article: A.N. Soe et al., C. R. Palevol 1 (2002) 153–160.     

Additional materials of Myanmarpithecus yarshensis (Amphipithecidae, Primates) from the middle Eocene Pondaung Formation

Myanmarpithecus yarshensis is an amphipithecid primate from the middle Eocene Pondaung Formation in Myanmar. It was previously known based on maxillary fragments with P⁴–M³ and mandibular fragments with C–P₃ and M_2–3. This study reports new materials for the genus, including a humeral head fragment, a lingual fragment of the right M², a lingual fragment of the right M³, and a left I¹. These new materials were collected from approximately the same point, and likely belonged to the same individual. The upper molar morphology and size of the new materials show similarity to those of the type specimen, indicating that the new materials can be assigned to M. yarshensis. The humeral head is the first postcranial element that is associated with dental materials for amphipithecids. The morphological similarity between the previously reported larger humerus and this specimen confirms the assignment of the former specimen to Amphipithecidae and suggests common locomotor adaptations in the family. The upper central incisor is large relative to the molar fragments, but is within the variation among extant platyrrhines. The tooth is spatulate-shaped and high crowned, and lacks the mesial process, indicating similarity to I¹ of haplorhines and clear differences from that of adapoids. It has been suggested that amphipithecids, including Myanmarpithecus, have affinities with notharctine adapoids, but the morphology of I¹ does not support the notharctine hypothesis of the Amphipithecidae.     

A new middle Eocene insectivore from the Mongolian People's Republic

A new genus and species, Bogdia orientalis, (Mammalia,Proteutheria, Pantolestidae) is described from the middle Eocene site of Tsagan-Khutel, from the valley of Lakes of the People's Republic of Mongolia. It is the first pantolestid species described from Asia.     

Squamate reptiles from the middle Eocene of Lissieu (France). A landmark in the middle Eocene of Europe

In Europe, faunas of squamates (lizards and snakes) from the middle Eocene are very poorly known, with the exception of those from the level MP 16 (latest middle Eocene). From the MP 11-MP 15 interval, squamates were previously reported only from Messel (MP 11, earliest middle Eocene) and from the untere and obere Mittelkohle of Geiseltal (MP 12 and MP 13 respectively) in Germany. The present report describes the middle Eocene assemblage of squamates from Lissieu (France), the first fauna reported from the level MP 14. Whereas fossils from Messel and Geiseltal are mostly articulated skeletons, fossils from Lissieu are represented by disarticulated bones; such fossils may be more easily compared to those from other Cenozoic localities, in which bones are almost always disarticulated. The fauna from Lissieu is more diverse than those from the Geiseltal sites and approximately as diverse as that from Messel as they are presently known; it is comprised of 17 distinct taxa. These taxa cannot be all identified to the species or genus level. They belong to iguanids, gekkonids, lacertids, anguids, thecoglossan platynotans, ophidians incertaesedis, boids, ?tropidophiines, “tropidophiids” incertaesedis, booids incertaesedis, and perhaps russellophiids. The fauna includes several new taxa but only a presumed tropidophiine snake may be named on the basis of the available material. The fauna from Lissieu is a mixture of taxa restricted to the middle Eocene and taxa known from older or younger levels. Taxa shared by Lissieu and the few other localities from the middle Eocene of Europe are rare. This fauna from Lissieu represents a stratigraphical landmark for the middle Eocene.     

A new genus and species of adapid primate from the middle Eocene of Alsace, and a new genus for 'Adapis' ruetimeyeri Stehlin, 1912

A new primate genus and species, represented by isolated teeth, is described from the middle Eocene Alsatian site of Bouxwiller. This new form is closely related to Egerkingen 'Adapis' ruetimeyeri, for which a new genus is proposed because of the important distinctions from type Adapis present in its dentition. Nonetheless, both new genera are closely related to Adapis and Leptadapis.     

Endocranial cast and morphology of the olfactory bulb of<Emphasis Type="Italic"> Amphipithecus mogaungensis</Emphasis> (latest middle Eocene of Myanmar)

A detailed endocranial cast of the olfactory bulb of Amphipithecus mogaungensis, a latest middle Eocene primate from the Pondaung Formation (Myanmar), was studied in comparison with some Paleogene primates, the olfactory bulb of which has been reported. The olfactory bulb of Amphipithecus is located just anterior to the postorbital constriction, that is, within the interorbital septum. It is relatively large and pedunculate, not overlapped by the frontal lobe, and consists of two parallell aligned bodies. The relative volume of the olfactory bulb shows the same pattern as in adapiforms, but the location and bilobed form are more similar to those of omomyoids than of adapiforms. Electronic Publication     

A new species of the bee genus Ctenoplectrella in middle Eocene Baltic amber (Hymenoptera, Megachilidae)

A new species of the extinct bee genus Ctenoplectrella Cockerell (Megachilinae: Ctenoplectrellini) is described and figured from two females preserved in middle Eocene (Lutetian) Baltic amber. Ctenoplectrella phaetonsp. n. is distinguished from its congeners on the basis of its body proportions, integumental sculpturing, wing venation, and pubescence, and is one of the more distinctive members of the genus. A revised key to the species of Ctenoplectrella is provided.     

New primate hind limb elements from the middle Eocene of China

The continued washing, sorting, and identification of middle Eocene (45 Mya) primates from the Shanghuang fissure-fillings (Jiangsu Province, China) have produced additional hind limb elements. All are isolated elements. The strepsirhine hind limb elements include a first metatarsal and a talus, which are appropriate in size and morphology to pertain to Adapoides troglodytes. Adapoides is interpreted as a quadrupedal-climbing (nonleaping) primate with similarities to living lorises and the fossil primate Adapis. The haplorhine hind limb elements are estimated to span a range of adult body sizes from tiny (17 g) to small (200 g). Included among the new sample of haplorhine hind limb specimens is the smallest primate talus reported thus far. These new postcranial specimens expand our understanding of early haplorhine hind limb anatomy and demonstrate additional similarities between Shanghuang eosimiids and other anthropoids.     

Amphibians and squamates from the middle Eocene of Namibia,with comments on pre-Miocene anurans from Africa

Three middle Eocene localities (Silica North, Silica South, Black Crow) recently discovered in Namibia have produced terrestrial faunas that rank among the few known from the period of insulation of Africa (Aptian-early Miocene). Collectively, the three localities have yielded anuran amphibians (one pipid frog, the earliest assemblage [three taxa] of ranoid frogs in Africa, one indeterminate family) and squamate reptiles (an amphisbaenian ‘lizard’, a snake that likely represents a colubroid, and two indeterminate ‘lizards’). These Eocene faunas suggest that ranoids, colubroids and African pipids are autochthonous to Africa. However, whereas pipids are vicariants inherited from West Gondwana, ranoids and colubroids (if really autochthonous) originated in Africa from unknown stems. Silica North and Silica South correspond to aquatic environments, permanent fresh water being present in the first locality; the environment of Black Crow was drier.