Middle-Eocene artiodactyls from Shanghuang (Jiangsu Province,Coastal China) and the diversity of basal dichobunoids in Asia

A new assemblage of basal dichobunoid artiodactyls from the middle-Eocene Shanghuang fissure fillings includes the diacodexeid Jiangsudon shanghuangensis gen. and sp. nov., a new species of the lantianine dichobunoid Elaschitotherium, Elaschitotherium crepaturus sp. nov., and an indeterminate suoid which is presently the earliest record of this clade. Diacodexeids are also represented by two forms provisionally referred to cf. Diacodexis sp. and to an indeterminate Diacodexeidae, respectively. The occurrence of diacodexeids in Shanghuang contrasts with the early and earliest middle-Eocene chronological range of the family in Europe and North America and suggests that the stratigraphic range of the family in Asia extends up to the middle Eocene. This may reflect particular habitats in coastal China that may have been relatively stable during the early and middle Eocene, thus preserving forest-dwelling artiodactyls that became extinct in the other Holarctic regions. Compared to other supposedly coeval North American, European, and Asian faunas, the Shanghuang mammalian assemblage is most similar to early Uintan faunas of North America but is also remarkable in recording forms close to taxa that are characteristic of the Wasatchian and Bridgerian North American Land Mammal Ages. The Irdinmanhan age of the Shanghuang fauna is supported by the mammalian assemblage recovered from the fissure D, but an Arshantan age cannot be completely ruled out at this point. Although the Shanghuang assemblage is biased towards preservation of small components of the mammalian fauna, the Shanghuang fauna provide an important and unique window into the Eocene diversity and early evolution of cetartiodactyls in eastern Asia.     

A long-bodied centriscoid fish from the basal Eocene of Kabardino-Balkaria, northern Caucasus, Russia

The Paleocene–Eocene transition is of crucial interest for interpreting the Cenozoic evolutionary radiation of vertebrates. A substantial increase of the number of vertebrate families occurred between the Late Paleocene and Early Eocene, with the appearance of most of the representatives of extant lineages. Basal Eocene marine fish diversity is currently poorly known, exclusively restricted to two assemblages from Denmark and Turkmenistan, respectively. Exceptionally well-preserved articulated skeletal remains of fishes have recently been discovered from a basal Eocene sapropelitic layer exposed along the Kheu River in the Republic of Kabardino-Balkaria, northern Caucasus, Russia. Here, we report on Gerpegezhus paviai gen. et sp. nov., a new peculiar syngnathoid fish from this new Ciscaucasian locality. The morphological structure of the single available specimen suggests that it is the first long-bodied member of the superfamily Centriscoidea, representing the sole member of the new family Gerpegezhidae, which forms a sister pair with the extant family Centriscidae.     

The first ceratopsian dinosaur from South Korea

In 2008, a new basal neoceratopsian was discovered in the Tando beds (Albian) of Tando Basin in South Korea. It represents the first ceratopsian dinosaur in the Korean peninsula and is assigned to Koreaceratops hwaseongensis gen. et sp. nov. Autapomorphies of Koreaceratops include very tall neural spines over five times higher than the associated centra in the distal caudals, and a unique astragalus divided into two fossae by a prominent craniocaudal ridge on the proximal surface. A phylogenetic analysis indicates that Koreaceratops is positioned between Archaeoceratops and all more derived neoceratopsians, and the elongation of caudal neural spines was an important derived character in non-ceratopsid neoceratopsians. The very tall caudal neural spines in Koreaceratops, Montanoceratops, Udanoceratops, Protoceratops, and Bagaceratops appear to be homoplasious, suggesting an independent adaptation, possibly for swimming. Skeletal evidence suggests that obligate quadrupedalism occurred gradually in neoceratopsians progressing from bipedal through facultative quadrupedalism, to complete quadrupedalism in Coronosauria.     

A structural intermediate between triisodontids and mesonychians (Mammalia, Acreodi) from the earliest Eocene of Portugal

A new mammal, Mondegodon eutrigonus gen. et sp. nov., is described from the earliest Eocene locality of Silveirinha, Portugal. This species shows dental adaptations indicative of a carnivorous diet. M. eutrigonus is referred to the order Acreodi and considered, along with the early Paleocene North American species Oxyclaenus cuspidatus, as a morphological intermediate between two groups of ungulate-like mammals, namely, the triisodontids and mesonychians. Considering that triisodontids are early to early-late Paleocene North American taxa, Mondegodon probably belongs to a group that migrated from North America towards Europe during the first part of the Paleocene. Mondegodon could represent thus a relict genus, belonging to the ante-Eocene European mammalian fauna. The occurrence of such a taxon in Southern Europe may reflect a period of isolation of this continental area during the Paleocene/Eocene transition. In this context, the non-occurrence of closely allied forms of Mondegodon in the Eocene North European mammalian faunas is significant. This strengthens the hypothesis that the mammalian fauna from Southern Europe is characterized by a certain degree of endemism during the earliest Eocene. Mondegodon also presents some striking similarities with an unnamed genus from the early Eocene of India which could represent the first Asian known transitional form between the triisodontids and mesonychians.     

Comparisons of dental morphology in river stingrays (Chondrichthyes: Potamotrygonidae) with new fossils from the middle Eocene of Peruvian Amazonia rekindle debate on their evolution

Endemic South American river stingrays (Potamotrygonidae), which include the most diversified living freshwater chondrichthyans, were conspicuously absent from pre-Neogene deposits in South America despite the fact that recent phylogenetic analyses strongly suggest an older origination for this clade. To date, the rare representatives of this family were mostly represented by ambiguous isolated remains. Here, we report 67 isolated fossil teeth of a new obligate freshwater dasyatoid (Potamotrygon ucayalensis nov. sp) from the fossiliferous level CTA-27 (Yahuarango Formation), near Contamana, in the Peruvian Amazonia. We assigned this sample to a new representative of Potamotrygon by comparison with numerous fresh jaws of living specimens of Potamotrygonidae, thus providing the first detailed review of dental morphology for this poorly understood clade. These new fossils fill a long stratigraphic gap by extending the family range down to the middle Eocene (～41 Mya). Moreover, the relative modernity and diversity in tooth morphology among Eocene freshwater stingrays (including Potamotrygon ucayalensis nov. sp. and coeval North American dasyatoids) indicate that the hypothetically marine ancestor of potamotrygonids probably invaded the rivers earlier than in the middle Eocene. The first potamotrygonids and affiliates were possibly more generalized and less endemic than now, which is consistent with an opportunistic filling of vacated ecospace.     

Temporal organization among pollination systems in a tropical seasonal forest

The Placerias/Downs’ Quarry complex in eastern Arizona, USA, is the most diverse Upper Triassic vertebrate locality known. We report a new short-faced archosauriform, Syntomiprosopus sucherorum gen. et sp. nov., represented by four incomplete mandibles, that expands that diversity with a morphology unique among Late Triassic archosauriforms. The most distinctive feature of Syntomiprosopus gen. nov. is its anteroposteriorly short, robust mandible with 3–4 anterior, a larger caniniform, and 1–3 “postcanine” alveoli. The size and shape of the alveoli and the preserved tips of replacement teeth preclude assignment to any taxon known only from teeth. Additional autapomorphies of S. sucherorum gen. et sp. nov. include a large fossa associated with the mandibular fenestra, an interdigitating suture of the surangular with the dentary, fine texture ornamenting the medial surface of the splenial, and a surangular ridge that completes a 90° arc. The external surfaces of the mandibles bear shallow, densely packed, irregular, fine pits and narrow, arcuate grooves. This combination of character states allows an archosauriform assignment; however, an associated and similarly sized braincase indicates that Syntomiprosopus n. gen. may represent previously unsampled disparity in early-diverging crocodylomorphs. The Placerias Quarry is Adamanian (Norian, maximum depositional age ~219 Ma), and this specimen appears to be an early example of shortening of the skull, which occurs later in diverse archosaur lineages, including the Late Cretaceous crocodyliform Simosuchus. This is another case where Triassic archosauriforms occupied morphospace converged upon by other archosaurs later in the Mesozoic and further demonstrates that even well-sampled localities can yield new taxa.

     

A new bolosaurid parareptile, Belebey chengi sp. nov., from the Middle Permian of China and its paleogeographic significance

A new bolosaurid parareptile, Belebey chengi sp. nov., is described from Dashankou, Gansu Province, China, a Middle Permian locality which is known mostly for its therapsid fauna. The material consists of well-preserved mandibular and anterior skull remains and currently represents the largest and latest surviving member of Bolosauridae. Phylogenetic analysis of bolosaurid interrelationships, the first analysis of any clade of Early Permian parareptiles, indicates that the new taxon groups consistently with the other (Russian) members of the genus Belebey, and forms the sister clade to the genus Bolosaurus from North America. The Early Permian Eudibamus cursoris from Germany falls into the basal most position within Bolosauridae. Our analysis also shows that the split between the main bolosaurid lineages must have occurred near or before the Permo-Carboniferous boundary and that the paleo-equatorial region of Laurasia probably served as the center of origination for these parareptiles. A similar pattern can be found in other clades of Paleozoic amniotes, suggesting that this may be the general trend in early amniote evolution.     

Numerical dating of the Eckfeld maar fossil site, Eifel, Germany: a calibration mark for the Eocene time scale

 Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian. In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By ⁴⁰Ar/³⁹Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has been established. The Eckfeld basalt inverse isochron date of 44.3±0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary at 44 Ma and, together with the 1995 time scale of Berggren et al., a time span ranging from 49 to 44 Ma for the Geiseltalian and from 44 to 37 Ma for the Robiacian, respectively. Additional ⁴⁰Ar/³⁹Ar dating on a genetically related basalt occurrence close to the maar confirms a period of volcanism of ca. 0.6 m.y. in the Eckfeld area, matching the oldest Eocene volcanic activity of the Hocheifel volcanic field. Received: 27 December 1999 / Accepted in revised form: 6 April 2000     

Artiodactyls from the Pondaung Formation (Myanmar): new data and reevaluation of the South Asian Faunal Province during the Middle Eocene

Although Asia is thought to have played a critical role in the radiation of artiodactyls, the fossil record of stem selenodonts (“dichobunoids”) remains dramatically poor in tropical Asian regions. In this study, we report a new dichobunid genus and species Cadutherium kyaukmagyii and a new basal ruminant genus and species Irrawadymeryx pondaungi, from the late Middle Eocene Pondaung Formation, Central Myanmar. Although the scarcity of the present material prevents any attempts to investigate the phylogenetic relationships of Cadutherium with contemporaneous forms from other Holarctic landmasses, this new form shed new light on the diversity of these small rabbit-like ungulates during a key period of their evolutionary history. Reexamination of the small-bodied artiodactyls from Pondaung leads us to propose new identifications of certain published specimens and, in turn, to investigate the temporal and geographic distribution of taxa recognized in the Pondaung Formation. Although fragmentary, these potential new taxa reveal an unsuspected diversity of small forms among artiodactyls of Pondaung. This addition to the Eocene record of dichobunoids and early ruminants provides further insight in the diversity of dental patterns among small artiodactyls from the Pondaung Formation and attests to the antiquity of these groups in Southeast Asia.     

The earliest record of birch mice from the Early Miocene Nei Mongol,China

The earliest species of birch mouse, Sicista primus sp. nov., was recovered from the 17-Ma-old (Early Miocene) Gashunyinadege locality, central Nei Mongol, China. It is ~9 Ma older than the previous first appearance datum of Sicista in Eurasia. This study indicates that North American Macrognathomys is a synonym of Eurasian Sicista, having 12 shared dental characters. As a result, the biogeography of dipodids indicates that Asian Sicista dispersed to North America as opposed to the hypothesis that Sicista originated from the North American clade. Sicista is one of the few extant rodent genera that originated as early as the Early Miocene.     

Eocene bunoselenodont Artiodactyla from southern Thailand and the early evolution of Ruminantia in South Asia

Although Asia is thought to have played a critical role in the basal radiation of Ruminantia, the fossil record of early selenodont artiodactyls remains poorly documented in this region. Dental remains of a new bunoselenodont artiodactyl are described from the late Eocene of Krabi, southern Thailand. This new form, Krabitherium waileki gen. et sp. nov, is tentatively referred to the Tragulidae (Ruminantia) on the basis of several dental features, including a weak Tragulus fold and the presence of a deep groove on the anterior face of the entoconid. Although this new form is suggestive of the enigmatic ?Gelocus gajensis Pilgrim 1912 from the “base of the Gaj” (lower Chitarwata Formation) of the Bugti Hills (Central Pakistan), K. waileki most likely represents an early representative of a relatively bunodont group of tragulids that includes the genus Dorcabune, known from the Miocene of south Asia. This addition to the Eocene record of early ruminants attests to the antiquity of the group in Southeast Asia and lends support to the hypothesis that the Tragulidae represents one of the first offshoots in the evolutionary history of Ruminantia.     

Diversity in the later Paleogene proboscidean radiation: a small barytheriid from the Oligocene of Dhofar Governorate,Sultanate of Oman

Despite significant recent improvements to our understanding of the early evolution of the Order Proboscidea (elephants and their extinct relatives), geographic sampling of the group’s Paleogene fossil record remains strongly biased, with the first ~30 million years of proboscidean evolution documented solely in near-coastal deposits of northern Africa. The considerable morphological disparity that is observable among the late Eocene and early Oligocene proboscideans of northern Africa suggests that other, as yet unsampled, parts of Afro-Arabia might have served as important centers for the early diversification of major proboscidean clades. Here we describe the oldest taxonomically diagnostic remains of a fossil proboscidean from the Arabian Peninsula, a partial mandible of Omanitherium dhofarensis (new genus and species), from near the base of the early Oligocene Shizar Member of the Ashawq Formation, in the Dhofar Governorate of the Sultanate of Oman. The molars and premolars of Omanitherium are morphologically intermediate between those of Arcanotherium and Barytherium from northern Africa, but its specialized lower incisors are unlike those of other known Paleogene proboscideans in being greatly enlarged, high-crowned, conical, and tusk-like. Omanitherium is consistently placed close to late Eocene Barytherium in our phylogenetic analyses, and we place the new genus in the Family Barytheriidae. Some features of Omanitherium, such as tusk-like lower second incisors, the possible loss of the lower central incisors, an enlarged anterior mental foramen, and inferred elongate mandibular symphysis and diminutive P₂, suggest a possible phylogenetic link with Deinotheriidae, an extinct family of proboscideans whose origins have long been mysterious.     

A new scincomorph lizard from the Palaeocene of Belgium and the origin of Scincoidea in Europe

Well-preserved jaw fragments and skull bones of a new scincomorphan lizard are described from the continental Hainin Formation (Middle Palaeocene) of the Mons Basin in southwestern Belgium. This taxon, Scincoideus haininensis gen. et sp. nov., is characterised by vermiculate dermal rugosities and represents the earliest formally recognised scincoid in Europe. It differs from cordylids (girdled lizards) by lacking the parietal downgrowth and differs from scincids (skinks) by having robustly built bones and a well-developed lingual cusp on tooth crowns. By its mosaic characters, S. haininensis is considered here as being a basal scincoid lizard close to the origin of cordylids and scincids. Palaeobiogeographic analysis suggests that scincoids were present in Europe from the Palaeocene or maybe even before the Cretaceous/Palaeogene boundary and that they were replaced by modern scincoids such as true scincids and cordylids during the Eocene. The origin of the latter two families in Europe was very likely related with the immigration of the first modern mammals.Electronic supplementary material  Supplementary material is available for this article at and accessible for authorised users.     

New postcrania of Deccanolestes from the Late Cretaceous of India and their bearing on the evolutionary and biogeographic history of euarchontan mammals

Extant species of the supraordinal mammal clade Euarchonta belong to the orders Primates, Scandentia, or Dermoptera. The fossil record of euarchontans suggests that they underwent their initial radiation during the Paleocene (65–55 million years ago) in North America, Eurasia, and Africa. The time and place of origin is poorly resolved due to lack of definitive fossils of euarchontan stem taxa. We describe a fragmentary humerus and two fragmentary ulnae from the latest Cretaceous of India that bear significantly on this issue. The fossils are tentatively referred to Deccanolestes cf. hislopi due to their small size and the fact that Deccanolestes is the only eutherian dental taxon to have been recovered from the same locality. The new fossils are used to evaluate the existing behavioral hypothesis that Deccanolestes was arboreal, and the competing phylogenetic hypotheses that Deccanolestes is a stem eutherian versus a stem euarchontan. The humerus resembles those of euarchontans in possessing a laterally keeled ulnar trochlea, a distinct zona conoidea, and a spherical capitulum. These features also suggest an arboreal lifestyle. The ulnar morphology is consistent with that of the humerus in reflecting an arboreal/scansorial animal. Detailed quantitative comparisons indicate that, despite morphological correlates to euarchontan-like arboreality, the humerus of Deccanolestes is morphologically intermediate between those of Cretaceous “condylarthran” mammals and definitive Cenozoic euarchontans. Additionally, humeri attributed to adapisoriculids are morphologically intermediate between those of Deccanolestes and definitive euarchontans. If adapisoriculids are euarchontans, as recently proposed, our results suggest that Deccanolestes is more basal. The tentative identification of Deccanolestes as a basal stem euarchontan suggests that (1) Placentalia began to diversify and Euarchonta originated before the Cretaceous–Tertiary boundary and (2) the Indian subcontinent, Eurasia, and Africa are more likely places of origin for Euarchonta than is North America.     

An opilioacarid mite in Cretaceous Burmese amber

A fossil opilioacarid mite (Parasitiformes: Opilioacarida) in Burmese amber is described as ?Opilioacarus groehni sp. nov. This ca. 99 Ma record (Upper Cretaceous: Cenomanian) represents only the third fossil example of this putatively basal mite lineage, the others originating from Eocene Baltic amber (ca. 44–49 Ma). Our new record is not only the oldest record of Opilioacarida, but it is also one of the oldest examples of the entire Parasitiformes clade. The presence of Opilioacarida—potentially Opiloacarus—in the Cretaceous of SE Asia suggests that some modern genus groups were formerly more widely distributed across the northern hemisphere, raising questions about previously suggested Gondwanan origins for these mites.     

Gaudeamus lavocati sp. nov. (Rodentia, Hystricognathi) from the early Oligocene of Zallah, Libya: first African caviomorph?

A new African species of hystricognathous rodent, Gaudeamus lavocati sp. nov., is described herein from the early Oligocene deposits of Zallah locality (Sirt basin, Central Libya). The dental morphology of this species is very close to that of some earliest South American caviomorphs. It allows a reinterpretation of molar crest homologies among earliest caviomorphs, pentalophodonty being confirmed as the plesiomorphic molar condition in Caviomorpha. This morphological resemblance argues for close affinities between Gaudeamus and earliest South American hystricognaths. Cladistic analysis supports Gaudeamus lavocati sp. nov. as the first known African representative of Caviomorpha, implying that its ancestors were part of the African phiomyid group that crossed the South Atlantic by a direct immigration route. Alternatively, the series of derived dental features of Gaudeamus could also be interpreted as evolutionary synchronous convergences of an African hystricognath lineage towards the specialized pattern of some caviomorphs. However, the high level of similarities concerning teeth morphology and enamel microstructure and the similar age of fossiliferous strata on both continents make this interpretation less probable. The phylogenetic position of this taxon is of considerable importance because it represents an enigmatic component of the phiomorph–caviomorph radiation in Africa and appears as a new clue toward the understanding of caviomorph origins.     

Skeletal remains of a diminutive primate from the Paleocene of Germany

Most living mammal orders, including our own, started their career during the first 10 million years of the Cenozoic, the Age of Mammals. The fossil record documents that early Paleogene adaptive radiations of various clades included tiny species of the size of living shrews. Remains of particularly diminutive limb bones are described from the late Paleocene site of Walbeck, Sachsen-Anhalt. Discovered in 1939, it has remained the only known Paleocene mammal-bearing locality from Germany. The remains are referred to the family Adapisoriculidae, which is considered on the basis of the present postcranial evidence to represent plesiadapiform primates rather than alleged lipotyphlan insectivores as previously proposed. The Walbeck fossils compete with the Early Eocene species Toliapina vinealis from Europe and Picromomys petersonorum from North America for the status of the smallest known primate, fossil and living. Their estimated body weights are as small as 10 g. The limb bones show features related to enhanced flexion at the elbow and hip joint, suggesting arboreal habits and environments such as terminal branches. The diminutive size and tooth morphology suggest feeding on small insects and other invertebrates. Postcranials are important to assess early radiations, such tiny specimens as the present ones are extremely scarce in the fossil record, however.     

High bat (Chiroptera) diversity in the Early Eocene of India

The geographic origin of bats is still unknown, and fossils of earliest bats are rare and poorly diversified, with, maybe, the exception of Europe. The earliest bats are recorded from the Early Eocene of North America, Europe, North Africa and Australia where they seem to appear suddenly and simultaneously. Until now, the oldest record in Asia was from the Middle Eocene. In this paper, we report the discovery of the oldest bat fauna of Asia dating from the Early Eocene of the Cambay Formation at Vastan Lignite Mine in Western India. The fossil taxa are described on the basis of well-preserved fragments of dentaries and lower teeth. The fauna is highly diversified and is represented by seven species belonging to seven genera and at least four families. Two genera and five species are new. Three species exhibit very primitive dental characters, whereas four others indicate more advanced states. Unexpectedly, this fauna presents strong affinities with the European faunas from the French Paris Basin and the German Messel locality. This could result from the limited fossil record of bats in Asia, but could also suggest new palaeobiogeographic scenarios involving the relative position of India during the Early Eocene.     

Earliest and first Northern Hemispheric hoatzin fossils substantiate Old World origin of a “Neotropic endemic”

The recent identification of hoatzins (Opisthocomiformes) in the Miocene of Africa showed part of the evolution of these birds, which are now only found in South America, to have taken place outside the Neotropic region. Here, we describe a new fossil species from the late Eocene of France, which constitutes the earliest fossil record of hoatzins and the first one from the Northern Hemisphere. Protoazin parisiensis gen. et sp. nov. is more closely related to South American Opisthocomiformes than the African taxon Namibiavis and substantiates an Old World origin of hoatzins, as well as a relictual distribution of the single extant species. Although recognition of hoatzins in Europe may challenge their presumed transatlantic dispersal, there are still no North American fossils in support of an alternative, Northern Hemispheric, dispersal route. In addition to Opisthocomiformes, other avian taxa are known from the Cenozoic of Europe, the extant representatives of which are only found in South America. Recognition of hoatzins in the early Cenozoic of Europe is of particular significance because Opisthocomiformes have a fossil record in sub-Saharan Africa, which supports the hypothesis that extinction of at least some of these “South American” groups outside the Neotropic region was not primarily due to climatic factors.     

The oldest African fox (Vulpes riffautae n. sp., Canidae, Carnivora) recovered in late Miocene deposits of the Djurab desert, Chad

We report on the oldest fox (Canidae) ever found in Africa. It is dated to 7 Ma based on the degree of evolution of the whole fauna. It belongs to a new species. Its overall size and some morphological characteristics distinguish the Chadian specimen from all the other foxes. The presence of Vulpes and of the genus Eucyon in slightly younger African locality, as well as in southwestern Europe in the late Miocene, may indicate that canids migrated in Europe from Africa through a trans-Mediterranean route.