Late Cretaceous Non-Marine Turtles of Asia: a Review of Taxonomic Diversity and Paleobiogeography

5th Turtle Evolution Symposium Rio de Janeiro, RJ, Brazil | July, 2015

Late Cretaceous non-marine turtles of Asia: a review of taxonomic diversity and paleobiogeography

Igor G. Danilov*1, Ekaterina M. Obraztsova 2, Vladimir B. Sukhanov 3

(1) Department of Herpetology, Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia. (2) Department of Vertebrate Zoology, Saint Petersburg State University, St. Petersburg, Russia. (3) Borisyak Paleontological Institute of the Russian Academy of Sciences, Moscow, Russia. * [email protected]

s Background. This report reviews data on taxonomic diversity and paleobiogeography of Late t

n Cretaceous (K2) non-marine turtles of Asia accumulated since latest reviews in 2000s. K2 i r non-marine turtles of Asia are known from four main geographical areas: Middle Asia- P

e Kazakhstan (MAK), Mongolia (MO), China (CH) and Japan (JA). r

P Methods. We critically reviewed composition of non-marine turtle assemblages of the K2 for each of the mentioned geographical area to make estimates of taxonomic diversity for different ages of the K2. Based on these data we analyzed temporal distribution of taxa of non-marine turtles and change in taxonomic diversity of turtle assemblages.

Results. K2 turtles of MAK are represented by eight suprageneric taxa – Adocidae (Ad), Carettochelyidae (Ca), Lindholmemydidae (Li), Macrobaenidae (Ma), Nanhsiungchelyidae (Na), Trionychidae (Tr), Eucryptodira indet. (Eu), and Testudines indet. (Te), of which Ad, Li, Ma and Tr are known from the Cenomanian(CE) – early Campanian(CA), whereas other taxa only from the CE-early Turonian(TU). Taxonomic diversity changes from 10–12 species and genera, 6–8 suprageneric taxa in the CE to 7 species and genera, 4 families in the late TU- early CA. K2 turtles of MO are represented by seven suprageneric taxa – Ad, Ca, Li, Ma, Meiolaniformes (Me), Na, and Tr, of which Li, Na and Tr are known from the CE- Maastrichtian(MA), Ad, Ca, and Ma, from the CE-Santonian(SA), and Me, only from the MA. Taxonomic diversity changes from 12 species, 10 genera, 6 families in the CE – SA, 8–9 species, 7–9 genera, 3 families in the CA, and 9 species, 7–8 genera, and 4 suprageneric taxa in the MA. K2 turtles of CH are represented by three suprageneric taxa (Li, Na, and Tr), but their precise temporal distribution is poorly known. Taxonomic diversity in the K2 is 12 species, 11–12 genera, and 3 families. K2 turtles of JA are represented by six suprageneric taxa (Ad, Ca, Na, Tr, Eu, and Te), of which Na are known from the CE-SA, Tr from the

PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1087v1 | CC-BY 4.0 Open Access | rec: 18 May 2015, publ: 18 May 2015 5th Turtle Evolution Symposium Rio de Janeiro, RJ, Brazil | July, 2015

Coniacian(CO)-CA, and other taxa from the CO-SA. Taxonomic diversity changes from 1 species, genus, and family in the CE-TU to 7 species and genera, and 5–6 suprageneric taxa in the CO-SA.

Discussion. In MAK, most significant transformation of turtle assemblages occurred in the CE-TU, whereas transformation in the SA-CA was less significant. On the contrary, in MO, most significant transformation occurred in the SA-CA, and less significant in the CA-MA. The patterns of transformation of the K2 turtle assemblages of CH and JA are not clear. The differences in the patterns of diversity and transformations of the K2 turtle assemblages in different geographical areas of Asia may be explained by different environmental conditions s t in these areas at that time and influence of such factors as transgressions in coastal areas n i

r (MAK and JA) and cooling and aridizations in inland areas (MO and CH). P

e Funding statement. This research was supported by grant of the Russian Scientific Fund 14-14-0015. r

PeerJ PrePrints | https://dx.doi.org/10.7287/peerj.preprints.1087v1 | CC-BY 4.0 Open Access | rec: 18 May 2015, publ: 18 May 2015