New early Eocene vertebrate assemblage from western India reveals a mixed fauna of European and Gondwana affinities

The Ypresian Cambay Shale Formation at Vastan and Mangrol lignite mines in Gujarat, western India, has yielded a rich vertebrate fauna with numerous taxa of European affinities. Here we report a new, approximately contemporary vertebrate assemblage from two fossiliferous layers in the nearby mine of Tadkeshwar. These layers have yielded a similar mammal fauna with the co-occurrence of the perissodactyl-like cambaytheriid Cambaytherium thewissi, the adapoid primates Marcgodinotius indicus and cf. Asiadapis cambayensis, and the hyaenodontid lndohyaenodon raoi. The presence of these species in both Vastan and Tadkeshwar mines and at different levels suggests that the deposits between the two major lignite seams represent a single land mammal age. Apart from the aforementioned species there is a new, smaller species of Cambaytherium, and a new genus and species of esthonychid tillodont. This fauna also contains the first large early Eocene vertebrates from India, including an unidentified Coryphodon-like pantodont, a dyrosaurid crocodyliform and a new giant madtsoiid snake. Among the Tadkeshwar vertebrates several taxa are of Gondwana affinities, such as Pelomedusoides turtles, dyr- osaurids, and large madtsoiids, attesting that the early Eocene was a crucial period in India during which Laurasian taxa of European affinities co-existed with relict taxa from Gondwana before the India-Asia collision. Our results suggest that terrestrial faunas could have dispersed to or from Europe during episodes of contact between the Indian subcontinent and different island blocks along the northern margin of the Neotethys, such as the Kohistan Ladakh island-arc system. Gondwana taxa might represent remnants of ghost lineages shared with Madagascar, which reached the Indian subcontinent during the late Cretaceous; alternatively they might have come from North Africa and passed along the southern margin of the Neotethys to reach the Indian subcontinent. These dispersals would have been possible as a result of favourable paleogeographic conditions such as the particular Neotethys conformation during the beginning of the early Eocene.

Eocene Antarctica:a window into the earliest history of modern whales

The Eocene–Oligocene Southern Ocean is thought to have played a major role in cetacean evolution.Yet,fossils from its heart—Antarctica—are rare,and come almost exclusively from the Eocene La Meseta and Submeseta formations of Marambio(Seymour)Island.Here,we provide a summary and update of this crucial fossil assemblage,and discuss its relevance in the broader context of cetacean evolution.To date,Eocene specimens from Antarctica include basilosaurids,a group of archaic stem cetaceans that had already fully adapted to life in water;and the archaic toothed mysticete Llanocetus,the second oldest crown cetacean on record(ca.34 Ma).This Eocene co-occurrence of stem and crown cetaceans is highly unusual,and otherwise only observed in Peru.Though related,at least some of the Antarctic species appear to be different from,and notably larger than their Peruvian counterparts,suggesting an early differentiation of the high latitude cetacean fauna.

Reassessment of historical sections from the Paleogene marine margin of the Congo Basin reveals an almost complete absence of Danian deposits

The early Paleogene is critical for understanding global biodiversity patterns in modern ecosystems. During this interval, Southern Hemisphere continents were largely characterized by isolation and faunal endemism following the breakup of Gondwana. Africa has been proposed as an important source area for the origin of several marine vertebrate groups but its Paleogene record is poorly sampled, especially from sub-Saharan Africa. To document the early Paleogene marine ecosystems of Central Africa, we revised the stratigraphic context of sedimentary deposits from three fossil-rich vertebrate localities: the Landana section in the Cabinda exclave(Angola), and the Manzadi and Bololo localities in western Democratic Republic of Congo.We provide more refined age constraints for these three localities based on invertebrate and vertebrate faunas, foraminiferal and dinoflagellate cyst assemblages, and carbon isotope records. We find an almost complete absence of Danian-aged rocks in the Landana section, contrary to prevailing interpretations over the last half a century(only the layer 1, at the base of the section, seems to be Danian). Refining the age of these Paleocene layers is crucial for analyzing fish evolution in a global framework, with implications for the early appearance of Scombridae(tunas and mackerels) and Tetraodontiformes(puffer fishes). The combination of vertebrate fossil records from Manzadi and Landana sections suggests important environmental changes around the K/Pg transition characterized by an important modification of the ichthyofauna. A small faunal shift may have occurred during the Selandian. More dramatic is the distinct decrease in overall richness that lasts from the Selandian to the Ypresian. The Lutetian of West Central Africa is characterized by the first appearance of numerous cartilaginous and bony fishes. Our analysis of the ichthyofauna moreover indicates two periods of faunal exchanges: one during the Paleocene, where Central Africa appears to have been a source for the European marine fauna, and another during the Eocene when Europe was the source of the Central Africa fauna. These data indicate that Central Africa has had connections with the Tethyian realm.

The first occurrence of Troodon-morphotype tooth in Jiayin,Heilongjiang,Northeast China

Abundant dinosaur remains have been discovered from the Heilongjiang/Amur area for over one hundred years.Among these discoveries,an isolated small theropod tooth recently found from the lower part of the Yuliangzi Formation of Jiayin displays highly distinctive morphological features.It can be identified as a Troodon-morphotype tooth based on mesiodistal constriction at the base of the crown and large,hook-like denticles extending the entire length of both carinae.Previously,Troodon remains were mainly found in North America.Some isolated Troodon teeth were also discovered in Blagoveschensk and Kundur localities on the left bank of the Heilongjiang river.This specimen represents the first occurrence of Troodon-morphotype tooth in Jiayin,Heilongjiang,Northeast China.The presence of this taxon in Jiayin,Blagoveschensk and Kundur localities in the Heilongjiang area provides new evidence for faunal exchange between North America and Asia through Cretaceous Beringia.