A Review of the Fossil Record of Turtles of the CladePan-Kinosternoidea

Abstract

Turtles of the total clade Pan-Kinosternoidea have a relatively poor fossil record that extends back to the Late Cretaceous (Campanian). The clade is found only in North America during its early history, but dispersed to Central America no later than the Miocene and to South America no later than the Pleistocene. Ancestral pan-kinosternoids were likely aquatic, bottom-walking omnivores or carnivores that preferred low-energy freshwater habitats. The Pan-Dermatemys lineage is often recovered in more fluvial habitats, and some are specialized to feed on aquatic vegetation. Alternatively, many representatives of Kinosternon evolved specializations (e.g., plastral lobe kinesis) that allowed them to successfully inhabit and disperse across more terrestrial habitats such as savannas and floodplains. A taxonomic review of the group concludes that of 42 named taxa, 27 are nomina valida (including two species of the controversial taxon Planetochelys), 14 are nomina invalida and only one a nomen dubium.

A Review of the Fossil Record of Turtles of the CladePan-Chelydridae

“…Although the available character evidence is conflicting, I here agree that E. cretacea is a pan-kinosternoid and therefore discuss it elsewhere (see Joyce and Bourque 2016). Finally, although Tullochelys montana Hutchison, 2013 from the early Paleocene of Montana was recently described as a new species of pan-chelydrid, I tentatively regard this as a pan-kinosternoid and therefore discuss it elsewhere as well (see Joyce and Bourque 2016).…”

“…Similarly, the Late Cretaceous (Maastrichtian) Emarginachelys cretacea Whetstone, 1978 was originally described as a pan-chelydrid (Whetstone 1978b) but was later reinterpreted to be a pan-kinosternoid, although an explicit rationale was not provided for this assessment (e.g., Meylan and Gaffney 1989;Holroyd and Hutchison 2002;Holroyd et al 2014). Although the available character evidence is conflicting, I here agree that E. cretacea is a pan-kinosternoid and therefore discuss it elsewhere (see Joyce and Bourque 2016). Finally, although Tullochelys montana Hutchison, 2013 from the early Paleocene of Montana was recently described as a new species of pan-chelydrid, I tentatively regard this as a pan-kinosternoid and therefore discuss it elsewhere as well (see Joyce and Bourque 2016).…”

An alternative interpretation of the Paleogene turtle Cardichelyon rogerwoodi as a hinged kinosternoid

“…Plastral scutes.-Testudinoids are unique among extant turtles by possessing paired gulars, humerals, pectorals, abdominals, femorals, and anals (Hutchison and Bramble, 1981), in contrast to extant chelydrids and kinosternoids, which possess intergulars, but lack pectorals (Joyce, 2016;Joyce and Bourque, 2016). A recent phylogenetic analysis of Americhelydia with focus on Chelydroidea (i.e., the clade consisting of Chelydridae and Kinosternoidea) concluded that the lack of pectorals is a synapomorphy of Chelydroidea, but that pectorals were secondarily reacquired within this clade, for instance in the Paleocene dermatemydid Agomphus pectoralis (Cope, 1868) (Lyson et al, 2017).…”

Projected changes in climatic suitability for Kinosternon turtles by 2050 and 2070

“…Kinosternon are relatively sparse (Bourque, 2012;Cadena, Jaramillo, & Paramo, 2007). The fossil record indicates that by the early to middle Miocene, Kinosternon existed across North America (Bourque, 2012(Bourque, , 2015Holman, 1998;Joyce & Bourque, 2016). Kinosternon were Multiple modeling approaches exist for evaluating how the distribution of organisms may change through time (Bakkenes et al, 2002;Huntley et al, 1995;Matthews et al, 2011).…”

“…Despite their widespread distribution, fossil examples of Kinosternon are relatively sparse (Bourque, ; Cadena, Jaramillo, & Paramo, ). The fossil record indicates that by the early to middle Miocene, Kinosternon existed across North America (Bourque, , ; Holman, ; Joyce & Bourque, ). Kinosternon were present in Central America by at least the early Pleistocene (Cisneros, ), and South America by the late Pleistocene (Cadena et al., ).…”