New Fossils, Systematics, and Biogeography of the Oldest Known Crown Primate <em>Teilhardina</em> from the Earliest Eocene of Asia, Europe, and North America
Project
ID: 00000C463
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Omomyiform primates are the most basal fossil haplorhines, with the oldest classified in the genus <i>Teilhardina</i> and known contemporaneously from Asia, Europe, and North America during the Paleocene-Eocene Thermal Maximum (PETM) ~56 mya. Characterization of morphology in this genus has been limited by small sample sizes and fragmentary fossils. A new dental sample (N=163) of the North American species <i>Teilhardina brandti</i> from PETM strata of the Bighorn Basin, Wyoming, documents previously unknown morphology and variation, prompting the need for a systematic revision of the genus. The P<sub>4</sub> of <i>T. brandti</i> expresses a range of variation that encompasses that of the recently named, slightly younger North American species ‘<i>Teilhardina gingerichi</i>,’ which is here synonymized with <i>T. brandti</i>. A new partial dentary preserving the alveoli for P<sub>1-2</sub> demonstrates that <i>T. brandti</i> variably expresses an unreduced, centrally-located P<sub>1</sub>, and in this regard is similar to that of <i>T. asiatica</i> from China. This observation, coupled with further documentation of variability in P<sub>1</sub> alveolar size, position, and presence in the European type species <i>T. belgica</i>, indicates that the original diagnosis of <i>T. asiatica</i> is insufficient at distinguishing this species from either <i>T. belgica</i> or <i>T. brandti</i>. Likewise, the basal omomyiform ‘<i>Archicebus achilles</i>’ requires revision to be distinguished from <i>Teilhardina</i>. Results from a phylogenetic analysis of 1,890 characters scored for omomyiforms, adapiforms, and other euarchontan mammals produces a novel clade including <i>T. magnoliana</i>, <i>T. brandti</i>, <i>T. asiatica</i>, and <i>T. belgica</i> to the exclusion of two species previously referred to <i>Teilhardina</i>, which are here classified in a new genus (<i>Bownomomys americanus</i> and <i>Bownomomys crassidens</i>). While hypotheses of relationships and inferred biogeographic patterns among species of <i>Teilhardina</i> could change with the discovery of more complete fossils, the results of these analyses indicate a similar probability that the genus originated in either Asia or North America.