A late early to early middle Eocene mammal assemblage from Bayan Ulan (Inner Mongolia,China): Implication for the reassessment of the Arshantan Asian Land Mammal Age

Paleogene mammal localities of North China are particularly well represented in the Erlian Basin, Inner Mongolia. Among them, the locality of Bayan Ulan is most famous for its late Paleocene Gashatan fauna. However, the younger Arshantan fauna of the same site is not well known, since no extensive study has been done so far. Here, we present a small mammal assemblage based on dental and tarsal material from a new Arshantan collection retrieved from the red beds of the late early to early middle Eocene Arshanto Formation at Bayan Ulan. It consists of at least six different taxa: the basal lagomorph Dawsonolagus antiquus, the large pantodont Pantolambdodon sp., the tapiroid Schlosseria magister, and the rhinocerotoids Hyrachyus crista and Rhodopagus guoi nov. sp. The assemblage is dominated by perissodactyls, especially Lophialetidae and Hyracodontidae. For the first time, p4-m1 of Dawsonolagus antiquus, tarsal material from Pantolambdodon sp., and lower dentition and tarsals of Hyrachyus crista are described and illustrated. Unlike other described Arshantan faunas, the Bayan Ulan Arshantan mammal assemblage has been collected exclusively from a single locality, which contributes to the reassessment of the misunderstood Arshantan Asian Land Mammal Age.     

A pantodont (Mammalia) from the latest Puercan North American Land Mammal Age (earliest Paleocene) of the Western Interior,USA

Abstract

Discovery of an Alcidedorbignya-like isolated upper molar in an early Paleocene (latest Puercan, Puercan 3, North American Land Mammal Age) local fauna found in the Tullock Member of the Fort Union Formation in northeastern Montana has been cited in the paleontological literature. This fossil is described, and a new genus and species, Crustulus fontanus, are established. They add to the taxonomic diversity of Puercan 3 local faunas in the North America Western Interior. The tooth’s morphology including a deep ectoflexus, nearly parallel preparacrista and postmetacrista, and expansion of the postcingulum, suggests evolution to accommodate increased herbivory. The appearance of C. fontanus with no clearly related taxa in older Puercan or Lancian (latest Cretaceous) local faunas of the currently sampled areas of the Western Interior indicates it probably was yet another post-Cretaceous/Paleogene boundary immigrant into this region. The few characters preserved in the single upper molar strongly suggest but do not conclusively indicate phylogenetic affinities with pantodonts. Perhaps C. fontanus was a member of yet another lineage stemming from the common ancestry of pantodonts and tillodonts. It is the oldest record of this complex group in North America.

http://www.zoobank.org/urn:lsid:zoobank.org:act:3643EA78-9A1A-4A2A-BFAF-4C2B6355B834     

广东南雄晚古新世哺乳类二新种

记述了发现在广东南雄晚古新世地层中的北柱兽目和钝脚目各一新种———中间沟柱兽 (Bothriostylopsmediussp .nov .)和大塘南岭兽 (Nanlingilambdadatangensissp .nov.)。中间沟柱兽的个体大小介于南方种 (B .notios)和进步种 (B .progressus)之间 ,但M3尤其是m3相对上述两种更大。大塘南岭兽比池江南岭兽 (N .chijiangensis)个体小、下颊齿跟座窄小、下后尖比下前尖高大。     

安徽贵池晚古新世哺乳类

记述了在安徽省贵池县梅埂地区红层中发现的3种哺乳动物化石,其中包括钝脚目全棱齿兽科1新属新种——翟氏贵池脊齿兽（Guichilambdazhaiigen．etsp．nov.）。新属与古脊齿兽属较为相似,但在个体大、上颊齿横宽、上臼齿中附尖弱、下颌骨具前外凸缘、下臼齿三角座和跟座V形夹角小等方面又明显不同于该属任何已知种。文中还根据所发现化石的进化水平和组合性质,并与国内外有关层位对比,定地层时代为晚古新世。     

CLASSIFICATION OF PANTOLAMBDODONTIDAE (PANTODONTA,MAMMALIA)

l.Weoriea1revlewl)PaatolambdodontidaeFossilsfoundbytheAsianExpeditionofAmericanMuseumofNaturalHistoryinSharaMurunarea,NeiMongolinl925andl928forthefirsttimeweredescribedbyGrangerandGregory(l934)asnewgenusandspe-cies,PantolambdodoninermisandP.lortis,andforwhichanewfamily,Pantola-mbdodontidae,wascreatedatthesametime.Inl978Tongdescribedafragmentary1owerjawwithm2andtrigonidofm3fromtheLatePaleoceneTaizicunFormation,Xinjiangandestablishedanewgenusandspecies,Dilambdaspeciosa.InthesameyearCho…