An extinct mud turtle of the Kinosternon flavescens group (Testudines, Kinosternidae) from the middle Miocene (late Barstovian) of New Mexico

ABSTRACT

The complete skeleton of a fossil mud turtle, Kinosternon pojoaque, n. sp., is described from the late Barstovian Rodent Pocket, San Ildefonso Locality of Santa Fe County, New Mexico. The new species represents the oldest member of the Kinosternon flavescens group and suggests that this clade first evolved in the southwestern United States, which, along with northern Mexico, is the center of diversity for these turtles today. The new taxon exhibits plastral characters that suggest phylogenetic affinities with Kinosternon angustipons, Kinosternon dunni, Kinosternon herrerai, Kinosternon hirtipes, and Kinosternon sonoriense and is interpreted here as an example of a morphological intermediate between the clade composed of these taxa and the flavescens group. The new fossil, along with other Miocene Kinosternon fossils from New Mexico, provides evidence that the flavescens clade likely diverged from other southwestern, Central, and South American Kinosternon by at least the late Barstovian, 14.3–13.3 million years ago.

ACKNOWLEDGMENTS

I thank G. S. Morgan (NMMNHS) for helpful discussions on New Mexico fossil localities and corresponding ages; C. Mehling and E. S. Gaffney (AMNH) for allowing me to borrow, prepare, and study fossils discussed here; R. Hulbert (FLMNH) for discussions, loan assistance, and manuscript comments; J. Bloch (FLMNH) for discussions and loan assistance; A. Hastings (FLMNH) for assistance, discussions, and manuscript comments; C. Manz (FLMNH) for discussions; L. Abraczinskas (MSUM), B. Schubert, and S. Wallace (ETMNH) for specimen loans; K. Krysko and M. Nickerson (FLMNH) for modern turtle specimen loans; S. Chester (YPM) for travel and lodging assistance; D. Ehret, C. May, and E. Simons for donations of modern specimens; S. Lad for assistance and discussions; A. Kerner for donation of UF 238539; J. Waldrop for donation of UF/TRO 2621; W. Joyce, P. O’Connor, R. Nydam, P. Barrett, and an anonymous reviewer for comments that greatly improved the manuscript; and J. B. Iverson for his many contributions on kinosternid turtles whose numerous specimens collected over the years (curated at the FLMNH) made the comparative component of this study feasible. This is University of Florida Contribution to Paleobiology 637.

Handling editor: Patrick O’Connor