A Review of the Fossil Record of Turtles of the CladeBaenidae

Abstract

The fossil record of the turtle clade Baenidae ranges from the Early Cretaceous (Aptian-Albian) to the Eocene. The group is present throughout North America during the Early Cretaceous, but is restricted to the western portions of the continents in the Late Cretaceous and Paleogene. No credible remains of the clade have been reported outside of North America to date. Baenids were warmadapted freshwater aquatic turtles that supported high levels of diversity at times through niche partitioning, particularly by adapting to a broad range of dietary preferences ranging from omnivorous to molluscivorous. Current phylogenies place Baenidae near the split of crown-group Testudines. Within Baenidae three more inclusive, named clades are recognized: Baenodda, Palatobaeninae and Eubaeninae. A taxonomic review of the group concludes that of 49 named taxa, 30 are nomina valida, 12 are nomina invalida and 7 are nomina dubia.

Allaeochelys libyca, a New Carettochelyine Turtle from the Middle Miocene (Langhian) of Libya

“…Six new characters were added, mostly from the work of Meylan (1988), to help further resolve the phylogenetic relationships of the ingroup. All nonpancarettochelyid taxa were scored for the new character using the same sources as Joyce (2007). Both the complete list of characters (Appendix 1) and the final character taxon matrix (see Appendix 2, supplementary material available online) are provided.…”

“…We included the new carettochelyine fossil and a broad sample of other fossil pancarettochelyids into the phylogenetic analysis of Joyce (2007) to rigorously analyze the phylogenetic relationships of pancarettochelyids in a global context. Newer versions of this matrix were not used (e.g., Joyce et al 2011;Anquetin 2012;Sterli et al 2013) because they universally added characters and taxa not relevant to trionychian systematics and because rampant homoplasy with the existing analysis already proved difficult to handle computationally.…”

“…Joyce); Allaeochelys magnifica (Hutchison et al, 2004) (as described by Hutchison et al 2004); Allaeochelys parayrei Noulet, 1867 (as described by de Broin 1977); and the new taxon described herein. Genus assignments follow Joyce (2014). Characters 60 and 89 of Joyce (2007) were modified by adding a character state.…”

“…Genus assignments follow Joyce (2014). Characters 60 and 89 of Joyce (2007) were modified by adding a character state. Six new characters were added, mostly from the work of Meylan (1988), to help further resolve the phylogenetic relationships of the ingroup.…”

“…Even though the fossil record of Pan-Carettochelys spans the Cretaceous and the Neogene, most of the taxa are based on shell remains, and little is known about the cranial anatomy of the group (Joyce 2014). To date, cranial material has only been reported for the Late Cretaceous Kizylkumemys schultzi (Nessov 1977) and the Eocene taxa Anosteira pulchra (Gaffney 1979), Allaeochelys crassesculpta (Harrassowitz 1922) and Allaeochelys delheidi (Lydekker 1889), but all descriptions are insufficient to allow making meaningful comparisons.…”