A new slider turtle (Testudines: Emydidae: Deirochelyinae:Trachemys) from the late Hemphillian (late Miocene/early Pliocene) of eastern Tennessee and the evolution of the deirochelyines

Abstract

Trachemys (Testudines: Emydidae) represents one of the most well-known turtle genera today. The evolution of Trachemys, while being heavily documented with fossil representatives, is not well understood. Numerous fossils from the late Hemphillian Gray Fossil Site (GFS) in northeastern Tennessee help to elucidate its evolution. The fossil Trachemys at the GFS represent a new species. The new taxon, Trachemys haugrudi, is described, and currently represents the most thoroughly described fossil emydid species known. A phylogenetic analysis, including 31 species, focusing on the subfamily Deirochelyinae is performed that includes the new fossil species, along with numerous other modern and fossil deirochelyine species, representing the first phylogenetic analysis published that includes several fossil deirochelyines. The phylogenetic analysis, utilizing morphological evidence, provides monophyletic clades of all modern deirochelyines, including Chrysemys, Deirochelys, Pseudemys, Malaclemys, Graptemys, and Trachemys. A strict consensus tree finds the recently described fossil species Graptemys kerneri to be part of a clade of Graptemys + Malaclemys. Three fossil taxa, including one previously referred to Pseudemys (Pseudemys caelata) and two to Deirochelys (Deirochelys carri and Deirochelys floridana) are found to form a clade with modern Deirochelys reticularia reticularia, with D. floridana sister to the other members of the clade. Chrysemys is found to be part of a basal polytomy with Deirochelys in relation to other deirochelyine taxa. Two fossil taxa previously referred to Chrysemys (Chrysemys timida and Chrysemys williamsi) form a paraphyly with the modern Chrysemys picta picta and Deirochelys, and may be referable to distinct genera. Additionally, fossil taxa previously attributed to Trachemys (Trachemys hillii, Trachemys idahoensis, Trachemys inflata, and Trachemys platymarginata) and T. haugrudi are found to form a clade separate from clades of northern and southern Trachemys species, potentially suggesting a distinct lineage of Trachemys with no modern survivors. Hypotheses of phylogenetic relationships mostly agree between the present study and previous ones, although the inclusion of fossil taxa provides further clues to the evolution of parts of the Deirochelyinae. The inclusion of more fossil taxa and characters may help resolve the placement of some taxa, and further elucidate the evolution of these New World turtles.

The Lapara Creek Fauna: Early Clarendonian of south Texas, USA

“…Trachemys appears to be the earliest record of this genus in North America, consistent with the interpretation of Fritz et al (2012). Jasinski (2018) provided a detailed discussion of the phylogenetic relationships within Trachemys and also concluded that the genus is monophyletic with multiple clades, both extinct and extant that are separated biogeographically. Although modern Trachemys is known to be saltwater tolerant for extended periods of time, it is commonly found in fresh water environments (Dunson and Seidel, 1986).…”

NeogeneCorylopsisseeds from eastern Tennessee

“…The GFS sediments preserve a diverse fauna and flora. The GFS fauna includes a wide variety of mammals (Wallace & Wang, 2004; Hulbert et al, 2009; Bourque & Schubert, 2015; Czaplewski, 2017; Doughty et al, 2018; Samuels et al, 2018) and a significant herpetofauna (Parmalee et al, 2002; Boardman & Schubert, 2011; Mead et al, 2012; McConnell & Zavada, 2013; Bourque & Schubert, 2015; Jasinski & Moscato, 2017; Jasinski, 2018), as well as birds and fish (Bourque & Schubert, 2015). The GFS flora is interpreted as a woodland community dominated by hickory ( Carya Nutt.…”

“…Specimens were photographed using a Nikon SMZ18 stereoscopic microscope with a Nikon DS-Ri2 camera under a 1.6x objective lens. Length-width measurements were taken using NIS-Elements software (1991-2018 Author Manuscript 5.10.01), and surface areas were calculated from photographs using ImageJ software (Schneider et al, 2012).…”

The first canid from the Gray Fossil Site in Tennessee: new perspective on the distribution and ecology ofBorophagus

“…Studies suggest that the site was formed when an ancient sinkhole collapsed, became a small lake, and then filled with sediment over several thousand years (Wallace and Wang, 2004; Shunk et al, 2006, 2009). This unique paleontological site records a diverse array of taxa, including a wide variety of flora, invertebrates, fish, amphibians, reptiles, birds, and small and large mammals (Parmalee et al, 2002; Wallace and Wang, 2004; DeSantis and Wallace, 2008; Boardman and Schubert, 2011; Zobaa et al, 2011; Mead et al, 2012; Ochoa et al, 2012, 2016; Worobiec et al, 2013; Bourque and Schubert, 2015; Jasinski and Moscato, 2017; Jasinski, 2018; Short et al, 2019; Siegert and Hermsen, 2020; Quirk and Hermsen, 2021). Flora and fauna at the site have been interpreted to indicate a relatively closed forested ecosystem (Ochoa et al, 2016; Samuels et al, 2018; Quirk and Hermsen, 2021).…”