New fossils of the oldest North American euprimate Teilhardina brandti (Omomyidae) from the paleocene–eocene thermal maximum

Abstract

More than 25 new specimens of Teilhardina brandti, one of the oldest known euprimates, are reported from earliest Eocene strata of the southern Bighorn Basin, Wyoming. The new fossils include the first upper dentitions, a dentary showing the lower dental formula for the first time, and the first postcrania ascribed to T. brandti (tarsals and terminal phalanges). The elongated navicular and long talar neck suggest that T. brandti was an active arboreal quadruped, and the terminal phalanges constitute the oldest evidence for nails in Euprimates. Phylogenetic analysis incorporating the new data indicates that T. brandti is more derived than T. belgica but less so than T. americana. The hypothesis that Teilhardina originated in Asia (T. asiatica) and dispersed westward to Europe (T. belgica) and then to North America (T. brandti and T. magnoliana) during the earliest Eocene Paleocene-Eocene Thermal Maximum is most consistent with available evidence, including the relative age of fossil samples and their stage of evolution.

Systematics and Phylogeny of Paleocene-Eocene Nyctitheriidae (Mammalia, Eulipotyphla?) with Description of a new Species from the Late Paleocene of the Clarks Fork Basin, Wyoming, USA

“…These species, Leptacodon nascimentoi, Placentidens lotus, Plagioctenodon dormaalensis, and Wyonycteris richardi all appear in the earliest Eocene, which suggests immigration in multiple clades at this time. There is also evidence for dispersal between North America and Europe at the Paleocene-Eocene boundary in other mammalian genera, including a proposed North America to Europe route for Palaeonictis (Chester et al 2010) and Europe to North America routes for both Teilhardina (Rose et al 2011) and Macrocranion (Smith et al 2002). This coincides with the Holarctic dispersal events in many other clades near the Paleocene-Eocene boundary, including hyaenodontid creodonts (Gingerich and Deutsch 1989), as well as the modern orders of primates, artiodactyls, and perissodactyls (Gingerich 2006;Smith et al 2006).…”

Hands of early primates

“…Most adapiform distal phalanges retain a feature more typically characteristic of falcular (claw bearing) phalanges: bilateral, well-developed nutrient foramina, as also seen in plesiadapiform distal phalanges, though these foramina face laterally in those of euprimates rather than ventrally as in plesiadapiforms (Maiolino et al, 2012). Known omomyiform distal phalanges are very similar to those of tarsiers and also tend to lack well-developed nutrient foramina (Dagosto, 1988;Rose et al, 2011).…”

“…While plesiadapiforms may represent primates of the Paleocene, at the beginning of the Eocene (55.8 million years ago), a new kind of primate appeared (Gingerich, 1986;Smith et al, 2006;Rose et al, 2011). These "new primates" are typically referable to either the Omomyiformes or Adapiformes, the two principal Eocene radiations of primates.…”

“…Though all manual distal phalanges identified for Eocene euprimates are unguliform, possessing a flattened apical tuft (which indicates the presence of a flattened nail rather than a claw or falcula), there appears to be substantial variation (Fig. 25) (Gregory, 1920;Dagosto, 1988;Gebo et al, 1991;Godinot, 1991Godinot, , 1992Franzen, 1993;Hamrick and Alexander, 1996;Rose et al, 2011;Ni et al, 2013). AMNH 127167 reveals Notharctus to have long, narrow, curved manual distal phalanges, possibly suggesting a more claw-like nail or functional tegulae (Godinot, 1991).…”

Evolution of postural diversity in primates as reflected by the size and shape of the medial tibial facet of the talus

“…Franzen et al, 2009). MRP analyses (run in PAUP) were then used to combine the results of these analyses with those of Springer et al (2012) and Janečka et al (2007) for extant euarchontans, Bloch et al (2007) for basal fossil euarchontans, Tornow (2008) and Rose et al (2011) for omomyiforms, Gunnell (2002) for notharctine adapiforms, Kay (2015) for living and extinct platyrrhines, and Strait and Grine (2004) for early hominins. The details of this approach closely followed Boyer and Seiffert (2013) and Boyer et al (2013a).…”