Fossil musk turtles (Kinosternidae, Sternotherus) from the late Miocene–early Pliocene (Hemphillian) of Tennessee and Florida

ABSTRACT

The oldest fossil musk turtles, genus Sternotherus, are reported from the Hemphillian of eastern Tennessee and central Florida. Sternotherus palaeodorus, n. sp., is known from five partial shells discovered at the late Miocene–early Pliocene (7–4.5 Ma; late Hemphillian) Gray Fossil Site in Washington County, Tennessee. Sternotherus palaeodorus possesses an enlarged intergular scute, wide first vertebral scute that overlaps peripheral set 1, posteriorly extensive hypoplastron to peripheral 7 contact, and a posteriorly situated inguinal musk duct pore (characteristics more typically seen in Kinosternon). A cladistic analysis recovered S. palaeodorus within crown group Sternotherus in the strict consensus and on the stem of Sternotherus in the majority rule consensus. Sternotherus bonevalleyensis, n. sp., from the Palmetto Fauna (5.5–5 Ma; late Hemphillian) of central Florida was perhaps contemporaneous with S. palaeodorus and is known only from isolated shell fragments. It is morphologically most similar to the Sternotherus minor complex and Sternotherus depressus. Subsequent Blancan fossils from the Suwannee River of Florida represent aff. S. minor peltifer. Additionally, a fragmentary left hyoplastron of cf. Sternotherus from Haile 19A, Alachua County, Florida, could be the oldest record for the genus (ca. 9–8.5 Ma; early Hemphillian). These accounts reveal that Sternotherus was diverse and moderately well distributed geographically by its first known fossil occurrences and support previous hypotheses that the Sternotherus minor complex evolved in the Gulf coastal plain and dispersed throughout that region since at least the latest Miocene–earliest Pliocene.

http://zoobank.org/urn:lsid:zoobank.org:pub:A1B8586C-0FCB-4B5E-B0B3-BD2D55B1ADC8

SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

ACKNOWLEDGMENTS

We thank J. Mead, S. Wallace, and B. Woodward (ETMNH) for fossil specimen loans, collections assistance, and discussions; S. Haugrud, B. Compton, J. Supplee, and numerous students and volunteers for their preparation efforts; K. Krysko (FLMNH), C. Guyer (AUM), and helpful personnel at the Guyer lab for modern specimen loans; P. Morse (FLMNH) for generating the maps used in Figure 1; E. Woodruff (FLMNH) for cladistic analysis assistance; R. Hulbert and J. Bloch (FLMNH) for discussions, collections assistance, and equipment use; K. MacKenzie (FLMNH) for collections assistance; T. Landberg for field assistance and modern specimen donations; C. Manz and S. Lad (FLMNH, UF) for discussions and assistance; W. Joyce, E. Cadena, R. Hulbert, and J. Sterli for helpful comments on the manuscript; A. Kerner for donation of US 19 Bridge Site and Aucilla River fossils; and J. Waldrop for his donation of the TRO Collection to the FLMNH, which included most of the Bone Valley specimens that were presented here. Curation of the TRO Collection was supported in part by the National Science Foundation (NSF) under grant CSBR 1203222. Excavation and curation of the GFS material was supported by NSF grant 0958985 and the Office of Research and Sponsored Programs at East Tennessee State University. This is University of Florida Contribution to Paleobiology 651.

Handling editor: Juliana Sterli.