The controversial family Adapisoriculidae, a group of shrew-sized Paleocene mammals, had proposed relationships with insectivores, marsupials and more recently to plesiadapiforms. Adapisoriculid remains are numerous in the early Paleocene locality of Hainin, Belgium, and allow us a test of these different phylogenetic hypotheses. Here, we identify the first tarsal bones of adapisoriculid mammals. The highly specialised bones indicate an arboreal mode of life with euarchontan affinity. Moreover, the tarsal bones are morphologically very close to those of the late Cretaceous Deccanolestes from the Deccan intertrappean beds of India, and also share several characters with the Paleocene plesiadapiforms and the extant cynocephalid dermopterans. The adapisoriculid affinities of Deccanolestes are also confirmed by tooth morphology, indicating that Deccanolestes is a primitive member of this family. These phylogenetic affinities suggest a paleobiogeographic scenario for the family with dispersal either via East Africa or across the Tethys area.
The Picrodontidae from the middle Palaeocene of North America are enigmatic placental mammals that were allied with various mammalian groups but are generally now considered to have close affinities to paromomyid and palaechthonid plesiadapiforms based on proposed dental synapomorphies. The picrodontid fossil record consists entirely of dental and gnathic remains except for one partial cranium of (AMNH 17180). Here, we use µCT technology to unveil previously undocumented morphology in AMNH 17180, describe and compare the basicranial morphology of a picrodontid for the first time, and incorporate these new data into cladistic analyses.
Objective: On the talus, the position and depth of the groove for the flexor hallucis longus tendon have been used to infer phylogenetic affinities and positional behaviors of fossil primates. This study quantifies aspects of the flexor hallucis longus groove (FHLG) to test if: (1) a lateral FHLG is a derived strepsirrhine feature, (2) a lateral FHLG reflects inverted and abducted foot postures, and (3) a deeper FHLG indicates a larger muscle.
Methods: We used linear measurements of microCT-generated models from a sample of euarchontans (n = 378 specimens, 125 species) to quantify FHLG position and depth.
Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have questioned its affinities to primates or even to placental mammals. Here we report the first (to our knowledge) nondental remains (tarsal bones) attributed to Purgatorius from the same earliest Paleocene deposits that have yielded numerous fossil dentitions of this poorly known mammal.
Department of Anthropology, Yale University, New Haven, CT 06520, USA Division of Vertebrate Paleontology, Yale Peabody Museum of Natural History, New Haven, CT 06520, USA.
Small-bodied, insectivorous Nyctitheriidae are known in the Palaeogene fossil record almost exclusively from teeth and fragmentary jaws and have been referred to Eulipotyphla (shrews, moles and hedgehogs) based on dental similarities. By contrast, isolated postcrania attributed to the group suggest arboreality and a relationship to Euarchonta (primates, treeshrews and colugos). Cretaceous-Palaeocene adapisoriculid insectivores have also been proposed as early euarchontans based on postcranial similarities.
Plesiadapids are extinct relatives of extant euarchontans (primates, dermopterans, and scandentians), which lived in North America and Europe during the Paleocene and Early Eocene. The only genus of plesiadapid whose species are absent from Paleocene strata is Platychoerops. Further, Platychoerops is the only group found in sediments post-dating the Paleocene-Eocene boundary (PEB) by a substantial period of time based on large samples.
