The oldest primates of modern aspect (euprimates) appear abruptly on the Holarctic continents during a brief episode of global warming known as the Paleocene-Eocene Thermal Maximum, at the beginning of the Eocene (~56 Ma). When they first appear in the fossil record, they are already divided into two distinct clades, Adapoidea (basal members of Strepsirrhini, which includes extant lemurs, lorises, and bushbabies) and Omomyidae (basal Haplorhini, which comprises living tarsiers, monkeys, and apes). Both groups have recently been discovered in the early Eocene Cambay Shale Formation of Vastan lignite mine, Gujarat, India, where they are known mainly from teeth and jaws. The Vastan fossils are dated at ~54.5 Myr based on associated dinoflagellates and isotope stratigraphy. Here, we describe new, exquisitely preserved limb bones of these Indian primates that reveal more primitive postcranial characteristics than have been previously documented for either clade, and differences between them are so minor that in many cases we cannot be certain to which group they belong. Nevertheless, the small distinctions observed in some elements foreshadow postcranial traits that distinguish the groups by the middle Eocene, suggesting that the Vastan primatesdthough slightly younger than the oldest known euprimatesdmay represent the most primitive known remnants of the divergence between the two great primate clades.
Located in
Library
/
RBINS Staff Publications 2016
The taxonomic affinities of fossils from theFrasnian succession of Be lgium previously described asphyllopod and phyllocarid crustacean shields are discussed.The rediscovery of the holotype of Ellipsocaris dewalquei,the type species of the genus Ellipsocaris Woodward inDewalque, 1882, allows to end the discussion on the taxo-nomic assignation of the genus Ellipsocaris. It is removedfrom the phyllopod crustaceans as interpreted originally andconsidered here as an ammonoid anaptychus. Furthermore, itis considered to be a junior synonym of the genus SidetesGiebel, 1847. Similarly, Van Straelen’s (1933) lower to middleFrasnian record Spathiocaris chagrinensis Ruedemann, 1916,is also an ammonoid anaptychus. Although ammonoids canbe relatively frequent in some Frasnian horizons of Belgium,anaptychi remain particularly scarce and the attribution to thepresent material to peculiar ammonoid species is not possible.
Located in
Library
/
RBINS Staff Publications 2017
