The early Eocene (Ypresian) Cambay Formation of Vastan Lignite Mine in Gujarat, western India, has produced a diverse assemblage of snakes including at least ten species that belong to the Madtsoiidae, Palaeophiidae (Palaeophis and Pterosphenus), Boidae, and several Caenophidia.Within the latter taxon, the Colubroidea are represented by Russellophis crassus sp.nov.(Russellophiidae) and by Procerophis sahnii gen.et sp.nov.Thaumastophis missiaeni gen.et sp.nov. is a caenophidian of uncertain family assignment.At least two other forms probably represent new genera and species, but they are not named; both appear to be related to the Caenophidia.The number of taxa that represent the Colubroidea or at least the Caenophidia, i.e., advanced snakes, is astonishing for the Eocene.This is consistent with the view that Asia played an important part in the early history of these taxa.The fossils come from marine and continental levels; however, no significant difference is evident between faunas from these levels.The fauna from Vastan Mine includes highly aquatic, amphibious, and terrestrial snakes.All are found in the continental levels, including the aquatic palaeophiids, whereas the marine beds yielded only two taxa.Vastan Mine is only the second locality in which the palaeophiids Palaeophis and Pterosphenus co-occur.The composition of the fauna from Vastan is on the whole similar to that of the early Eocene of Europe; however, comparisons with early Eocene faunas of other continents are not possible because they are poorly known or unknown.
ABSTRACT We describe a three-dimensionally prepared specimen of Baryphracta deponiae from the middle Eocene of Messel (Darmstadt, Germany). Based on a phylogenetic analysis that included the addition of 20 novel scorings for characters previously unavailable for this taxon and the recoding of four additional characters, we found B. deponiae to be nested within Diplocynodon. We propose the new combination Diplocynodon deponiae. The name Baryphracta is thus a junior synonym of Diplocynodon. The small species D. deponiae (∼1 m in total length) shares several features with other species of Diplocynodon, including the presence of two subequal alveoli in the maxilla and dentary, exclusion of the splenial from the symphysis, and the shape of the iliac blade. However, it also differs in a few characters, including the presence of molariform teeth and the extension of osteoderms along the limbs and tail. Such osteodermal cover, which developed very early in ontogeny, easily distinguishes even small-sized specimens of D. deponiae from the co-occurring Diplocynodon darwini. The crocodylian fauna of Messel shows an astonishing diversity including at least seven taxa, with two belonging to the same genus. The two congeners exhibit differences in dentition and size that likely allowed for niche partitioning that minimized competition, thereby allowing them to be syntopic.
The Paleocene-Eocene boundary is defined chemostratigraphically by the onset of a 100 kyr global carbon isotope excursion (CIE) that is recognized in marine and continental strata in both carbonate and dispersed organic carbon. The CIE is important in continental sections as a proxy for environmental change during the Paleocene-Eocene thermal maximum (PETM), which clearly affected faunal succession in Paleocene-Eocene mammals. At Polecat Bench in the northern Bighorn Basin, Wyoming, the CIE is in the Willwood Formation, where it spans four mammalian biozones from part of latest Clarkforkian Cf-3, through early Wasatchian Wa-M (Meniscotherium), Wa-0, and part of Wa-1. Here we report a new high-resolution study of the CIE recorded in dispersed organic carbon of the basal Willwood Formation in the Honeycombs area of the southern Bighorn Basin. In the Honeycombs area, 58 isotope sample sites span a vertical section of 71 meters, including the Wa-M locality 'Halfway Hill North' with both Meniscotherium and a Heptodon-like perissodactyl, and the richly fossiliferous Wa-0 wash site 'Castle Gardens' yielding a diverse mammalian fauna. Total organic carbon in the Honeycombs section is in the range of 0.1 to 0.4 percent by weight, and CaCO3 is notably lacking except in the Castle Gardens interval where it reaches ca. 3 percent. Pre- and post-excursion values of δ13Corg (PDB) range from −26.2 to −24.1 permil. The Honeycombs CIE is about 42 m thick, and CIE excursion values range from −28.8 to −26.2 permil. The Honeycombs area is important because the Halfway Hill North locality is the first to yield a perissodactyl from the Wa-M Meniscotherium zone, and the Castle Gardens wash site is the first to yield abundant evidence of Wa-0 zone microvertebrates. As at Polecat Bench, the Meniscotherium zone in the Honeycombs area is in the lower part of the CIE, and Castle Gardens and other Wa-0 sites are in the longer middle and upper parts, starting near or after the maximum negative excursion. The CIE at Polecat Bench includes a series of 5 to 6 negative-excursion landmarks that are spaced, on average, about 8.5 m apart. These are tentatively interpreted as 21-kyr orbital precession cycles like those inferred for paleosol color. Negative-excursion landmarks are present in the Honeycombs CIE as well, but these are fewer and part of the Honeycombs section may be condensed or missing. Full understanding of the Paleocene-Eocene biotic transition will require investigation at even finer scales of temporal resolution, and results reported here suggest that finer-scale studies should be possible.
We describe new avian fossils from the Boom Formation of Belgium, which almost double the num- ber of bird taxa known from this part of the Rupelian stratotype. Three galliform species can, at least tentatively, be assigned to the paraortygid species Paraortyx brancoi, P. lorteti, and Pirortyx major. Among the fossils is a partial sternum, which shows that Paraortyx lacks a spina interna. The absence of this structure is plesiomor- phic for Galliformes and probably related to the absence of a large crop, thus indicating that Paraortygidae were not yet adapted to the regular processing of coarse and dry food. Two distal humeri belong to Trogoniformes (trogons) and Upupiformes (hoopoes, woodhoopoes, and allies), respectively. A femur is tentatively assigned to Phaethontiformes (tropicbirds), and a carpometacarpus is, likewise tentatively, referred to Threskiornithidae (ibises and spoonbills). We finally comment on the affinities of Anas benedeni Sharpe, 1899 and detail that this species most likely belongs to Gaviiformes (loons).
The famous Flaming Cliffs area in Mongolia has long been known to yield abundant Cretaceous (Djadohkta Fm.) and early Paleogene (Khashat Fm.) fossil vertebrates. This region was revisited in 1999 with D. Dashzeveg. During fieldwork at the Gashato locality, a small fossiliferous sandy lens (<1 m3) in Member 1 of the late Paleocene Khashat Formation was completely excavated and screen-washed. Except some rare mixodont remains, the mammal fossils in this lens consist of remains of the arctostylopid Palaeostylops. Over 250 upper and lower jaw fragments are recorded, representing both described species of Palaeostylops, with a minimum number of 24 individuals for P. iturus and 15 for P. macrodon. The finding of such a concentration of individuals may have important implications for the ecology of arctostylopids. The high number of dental remains from a single lens allows to illustrate the morphometric and morphological variability of both forms from a single population. Documenting the variability in both forms is important because they have been variously suggested to represent one sexually dimorphic species, two separate species or even two separate genera. Study of these new fossil specimens will therefore provide a test of these different taxonomical interpretations. Until recently, the Asian and North American Arctostylopidae were only known by dental remains, and they were generally allied with the endemic South American Notoungulata. A recent study of the first unambiguously identified arctostylopid tarsals however suggested that arctostylopids are not notoungulates, but instead are a family of non-gliroid Gliriformes, and moreover characterised Palaeostylops as a moderately specialised cursorial or saltatorial form. The arctostylopid fossils reported here not only include fossil teeth and tarsals, but also previously unknown other postcranial remains, including a distal part of a humerus, a proximal part of a femur and a distal part of a tibia. These new elements can therefore give additional insights in both the phylogeny and the locomotory habits of the poorly known arctostylopids.
KEYWORDS . — paleontology, paleogeography, mammals, Paleocene-Eocene. SUMMARY . — The mammals, discreet during the dinosaur period, see their size and number of species increase after the extinction of these giants 65 million years ago. This is the beginning of the Age of Mammals. But it is o nly at the beginning of the Eocene 55 million years ago during an extremely fast and i ntense global warming called the PETM ( Paleocene Eocene Thermal Maximum ) that their diversity explodes. New groups then suddenly appear on the three northern c ontinents via intercontinental land bridges across which they make important dispersals . These new groups, called “modern mammals”, are the rodents, lagomorphs, perissodactyls, artiodactyls, cetaceans, primates, carnivorans and bats. Although these eight groups represent 83 % of the extant mammal species diversity, their ances tors are still unknown. A short overview of the knowledge and recent progress on this research is here presented based on Belgian studies and expeditions, especially in I ndia and China. MOTS -CLES. — paleontologie, paleogeographie, mammiferes, Paleocene-Eocene. RESUME . — Les mammiferes, discrets durant la periode des dinosaures, voient leur taille et leur nombre d’especes augmenter a partir de l’extinction de ces geants il y a 65 millions d’annees. C’est le debut de l’Age des mammiferes. Mais il faudra attendre l’aube de l’Eocene il y a 55 millions d’annees lors d’un rechauffement global extremement rapide et intense connu sous le nom de PETM ( Paleocene Eocene Thermal Maximum ) pour voir leur diversite explosee. De nouveaux gr oupes apparaissent alors soudainement sur les trois conti nents de l’hemisphere nord grâce a des ponts terrestres intercontinentaux par lesquels ils effectuent de grandes dispersions. Ces nouveaux groupes qualifies de « mammiferes modernes » sont les rongeurs, lagomorphes, perissodactyles, artiodactyles, cetace s, primates, carnivores et chauvessouris. Bien que ces huit groupes representent 83 % de la diversite des especes actuelles de mammiferes, leurs ancetres sont encore inconnus. Un bref apercu des connaissances et progres recents est presente ici sur base des et udes et expeditions belges, en particulier en Inde et en Chine. TREFWOORDEN . — paleontologie, paleogeografie, zoogdieren, Pale oceen-Eoceen. SAMENVATTING . — De zoogdieren, die onopvallend waren tijdens de periode van de dinosauriers, kennen een toename in grootte en aant al na het verdwijnen van deze giganten 65 miljoen jaar geleden. Dit is het begin van de Tijd van de Zoogdieren. Toch is het wachten tot het aanbreken van het Eoceen 55 miljoen jaar geleden tijdens een periode van extreem snelle en intense klimaatopwarming gekend als het PETM (Paleocene Eocene Thermal Maximum ), tot hun diversiteit werkelijk explodeert. Dan verschijnen plots nieuwe groepen op de drie contine nten van de noordelijke hemisfeer dankzij intercontinentale landbruggen waarover ze v erre migraties uitvoeren. Deze nieuwe groepen die we de moderne zoogdieren noemen zijn de knaagdieren, haasachtigen, onevenhoevigen, evenhoevigen, walvissen, primaten, carnivoren en
Among the archaic ‘ungulates,’ pleuraspidotheriids are well documented by skulls and postcranial elements of Pleuraspidotherium from Berru and Cernay-lès-Reims (late Paleocene, Paris Basin, France). Nevertheless, the relationships of pleuraspidotheriids (i.e., Pleuraspidotherium, Orthaspidotherium, and Hilalia) to other ‘condylarths’ have not been conclusively settled. They have been related to the typically North American Meniscotheriidae, Phenacodontidae, and Mioclaenidae, and even to the modern ungulates Perissodactyla and Artiodactyla. We here provide additional data, especially from the first complete skull of Orthaspidotherium, and highlight a mosaic of plesiomorphic and derived characters that distinguish Pleuraspidotheriidae from all other ‘ungulates.’ Their basicranial morphology approximates the ancestral morphotype of artiodactyls, but this results from symplesiomorphies. Pleuraspidotheriids exhibit the following synapomorphies: strong processes on the petrosal and enclosure of the facial nerve by the tympanic process and tympanohyal. Although their dentition resembles that of perissodactyls, meniscotheriids, and phenacodontids, the development of a pseudohypocone from the metaconule unambiguously shows that these similarities arose by convergence. Other evolutionary tendencies are the strong reduction of the hypoconulid, molarization of last premolars, development of lingual cingulum on M2, lengthening of the snout, and presence of diastemata. The pleuraspidotheriid tarsal morphology is primitive and not uncommon among ‘condylarths’ but presents some synapomorphies such as a calcaneum with a transverse cuboid facet and an astragalus with a squatting facet, cotylar fossa, and sustentacular hinge. Our study does not indicate a close relationship of Pleuraspidotheriidae with any of the archaic or modern ‘ungulates’ mentioned above. Instead, primitive arctocyonids could represent a possible ancestral morphotype for pleuraspidotheriids.
We report the discovery of the earliest European carnivoraforms, based on two new taxa from the latest Paleocene of France and Romania. A new species of Vassacyon, V. prieuri, from the locality of Rivecourt (MP6b; Oise, France) (MP = Mammalian Paleogene reference levels) is described based on a dentary fragment and isolated teeth. This species displays several primitive features compared with species of Vassacyon known from the early Eocene of North America and Europe. A second Paleocene carnivoraform, cf. Gracilocyon sp., is described based on fragmentary specimens from the locality of Jibou (MP6b; Transylvania, Romania). Carnivoraformes were previously unknown in Europe before the Eocene, and Vassacyon prieuri and cf. Gracilocyon sp. are their oldest records in Europe. These discoveries favor the hypothesis of a dispersal of these two genera from Europe to North America during the Paleocene-Eocene Thermal Maximum. Vassacyon prieuri and cf. Gracilocyon sp. strengthen support for the level MP6b and its correlation with the Clarkforkian. The geographic origin of the Carnivoraformes remains unknown. However, based on the observed biochronological and geographic distributions of the carnivoraforms, we infer a possible Asian origin for this group. In this scenario, Gracilocyon and Vassacyon dispersed to Europe during the Clarkforkian MP6b time, probably together with rodent taxa, whereas Uintacyon dispersed from Asia to North America shortly after rodents and tillodonts. http://zoobank.org/urn:lsid:zoobank.org:pub:FC885E7F-877A-4454-9902-DF118B8C8693 SUPPLEMENTAL DATA—Supplemental materials are available forthis article for free at www.tandfonline.com/UJVP Citation for this article: Solé, F., T. Smith, E. de Bast, V. Codrea, and E. Gheerbrant. 2016. New carnivoraforms from the latest Paleocene of Europe and their bearing on the origin and radiation of Carnivoraformes (Carnivoramorpha, Mammalia). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1082480.
