An updated mammal biochronology and biogeography for the paleocene and early eocene of Asia

Paleomammalogists often use a biochronological system of regional Land Mammal Ages (LMAs) to designate intervals of time defined by specific events in the evolutionary history of mammals. In North America and Europe, this biochronological framework is fairly well known and has been partially correlated to the global timescale (Secord et al. 2006; Smith & Smith 2003). The Asian early Paleogene mammal biochronology is less precise, due to our previously limited knowledge of these faunas. Moreover, the endemic nature of these Asian faunas and the few absolute ages available have made the correlation and dating of these faunas problematic. Wang et al. (2007) provided a recent synthesis of the Chinese Paleogene mammal radiations, but Ting (1998) was the last to provide a detailed study of the Paleocene and Early Eocene Asian LMAs (ALMAs). However, in the past decade research efforts have rapidly increased the available data on the Asian faunas, creating the need for a detailed update of the existing biochronological framework and its biogeographical interpretation. Faunal data from Asian early Paleogene mammal sites were analysed with Appearance Event Ordination to obtain a temporally ordered faunal succession. Faunal data and analysis results were studied in detail to define biochronological boundaries corresponding to major faunal turnovers, and to clearly characterise the different ALMAs. The new biochronology allows an improved correlation of ALMAs with North American and European LMAs, and to better understand the biogeography of Paleocene and Early Eocene Asian mammals. The poorly known Shanghuan represents the oldest Paleocene ALMA, and is characterised by an assemblage dominated by primitive gliriforms and pantodonts. The following Nongshanian ALMA is characterised by an endemic specialisation and diversification. Especially gliriforms radiate, with the diversification of Anagalidae and Pseudictopidae, the first appearance of the gliriform family Arctostylopidae, and, most notably, the appearance of true Glires, represented by Eurymylidae and Mimotonidae. The poor knowledge and primitive, endemic nature of the Shanghuan and Nongshanian faunas complicates their correlation, but the Shanghuan-Nongshanian boundary is often correlated with the Torrejonian-Tiffanian boundary in North America, and this hypothesis was recently magnetostratigraphically corroborated (Clyde et al. 2008). Both boundaries thus seem to represent independent but synchronous turnovers of endemic taxa, and were possibly triggered by the start of a period of global cooling. The Gashatan ALMA is characterised by the first appearance of rodents, prodinoceratids and hyaenodontids, all of which supposedly evolved in Asia. However, neoplagiaulacids, nyctitheriids, cimolestids and carpolestids also make their first appearance in Asia during the Gashatan, and represent North American immigrants (Missiaen and Smith 2008). Conversely, during this period Asian mammals were also able to invade North America, with a first wave consisting of arctostylopids and prodinoceratids arriving at the start of Tiffanian-5a, and a second wave consisting of rodents, tillodonts and coryphodontids at the start of the Clarkforkian (Secord et al. 2006). The start of the Gashatan is thus no younger than Tiffanian-5a, but may prove to be even older. Although it is not possible to constrain the exact timing or duration of these migration waves at the start of the Gashatan, available evidence is most consistent with two discrete dispersal intervals approximately 1.3 Ma apart. The Bumbanian ALMA is characterised by the first appearance of artiodactyls, perissodactyls and primates, similar to their appearance in North America and Europe at the start of the Eocene, and the Gashatan-Bumbanian boundary is traditionally correlated to the Paleocene-Eocene boundary. Contrasting with dispersal at the start of the Gashatan, dispersal during the Bumbanian seems to have been possible during a more extended period of time and was also possible directly between Asia and Europe (Ting 1998; Smith et al. 2006)

Beyond the 2nd Fermi Pulsar Catalog

Over thirteen times more gamma-ray pulsars have now been studied with the Large Area Telescope on NASA's Fermi satellite than the ten seen with the Compton Gamma-Ray Observatory in the nineteen-nineties. The large sample is diverse, allowing better understanding both of the pulsars themselves and of their roles in various cosmic processes. Here we explore the prospects for even more gamma-ray pulsars as Fermi enters the 2nd half of its nominal ten-year mission. New pulsars will naturally tend to be fainter than the first ones discovered. Some of them will have unusual characteristics compared to the current population, which may help discriminate between models. We illustrate a vision of the future with a sample of six pulsars discovered after the 2nd Fermi Pulsar Catalog was written.Comment: 6 pages, to appear in the proceedings of "The Fast and the Furious: Energetic Phenomena in Isolated Neutron Stars, Pulsar Wind Nebulae and Supernova Remnants",ESAC, Madrid, Spain, 22 - 24 May 2013 http://xmm.esac.esa.int/external/xmm_science/workshops/2013_science/, to be published as a regular issue of the Astronomische Nachrichten / Astronomical Notes (AN

Cymbalophus cuniculus from the early Eocene of Erquelinnes (Belgium), and its implications for basal Perissodactyl phylogeny

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A new species of Archaeoryctes from the Middle Paleocene of China and the phylogenetic diversification of Didymoconidae

Didymoconidae are an enigmatic group of Asian endemic insectivorous mammals. We describe the new didymoconid species Archaeoryctes wangi sp. nov. from the Upper Member of the Wanghudun Formation (Middle Paleocene). This new species from the Qianshan Basin (Anhui Province, China) forms an interesting geographical intermediate between A. notialis from South China and A. borealis and A. euryalis from the Mongolian Plateau. To better understand the origin and evolutionary diversification of Didymoconidae, we performed a cladistic and stratocladistic study of the Didymoconidae and various outgroups. This study of dental material did not resolve the higher level affinities of Didymoconidae, but confirms the validity of the family and its distinctiveness from the morphologically similar Sarcodontidae. Moreover, our results corroborate the current didymoconid classification with the distinction of three subfamilies: “Ardynictinae”, Kennatheriinae and Didymoconinae; “Ardynictinae” are a paraphyletic stemgroup for the two other subfamilies. Our results suggest three distinct didymoconid radiations: (1) primitive ardynictines appeared in South China from the start of the Nongshanian; their evolution continues on the Mongolian Plateau with (2) the radiation of more evolved ardynictines and kennatheriines at the start of the Middle Eocene Arshantan and (3) the origin of didymoconines at the start of the Late Eocene Ergilian

Paleocene-Eocene Land Mammals From Three New Latest Clarkforkian And Earliest Wasatchian Wash Sites At Polecat Bench In the Northern Bighorn Basin, Wyoming

http://deepblue.lib.umich.edu/bitstream/2027.42/49356/1/Vol 31 No11 final 12-11-06.pd

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

AbstractThe 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 Indohyaenodon 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, dyrosaurids, 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