Browsing by Author "Krause, David W."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Kinkonychelys, a new side-necked turtle (Pelomedusoides, Bothremydidae) from the late Cretaceous of Madagascar. (American Museum novitates, no. 3662)(New York, NY : American Museum of Natural History., 2009) Gaffney, Eugene S.; Krause, David W.; Zalmout, Iyad S.The type specimen of Kinkonychelys rogersi, n. gen. et sp., is the first turtle skull to be described from the pre-Holocene fossil record of Madagascar. This specimen, a nearly complete cranium, along with several referred specimens (a series of maxillae and a partial lower jaw), was recovered from the Maastrichtian Maevarano Formation in the Mahajanga Basin of northwestern Madagascar. A braincase with the diagnostic characters of Kinkonychelys, but differing in the position of the jaw articulation, formation of the foramen nervi facialis, and a number of other characters, was found in the same rock unit and is provisionally identified as belonging to Kinkonychelys sp., a presumed distinct, but closely related species, too incomplete to be diagnosed at present. Kinkonychelys is a bothremydid because it has the diagnostic characters of an exoccipitalquadrate contact and a fully enclosed incisura columellae auris (Gaffney et al., 2006). Kinkonychelys belongs to the tribe Kurmademydini, previously known to include only Sankuchemys and Kurmademys from the late Cretaceous of India, because it has a deep fossa pterygoidea, a foramen stapediotemporale facing dorsally, a jugal not retracted from the orbit, a deep fossa precolumellaris, and a large, wide antrum postoticum. Kinkonychelys rogersi and Kinkonychelys sp. both possess a unique form of the overlapping fossa pterygoidea. A cladistic analysis of Kinkonychelys reveals that it is nested within the tribe Kurmademydini of Gaffney et al. (2006) and is related to the other taxa in the tribe as follows: (Sankuchemys (Kinkonychelys+Kurmademys)). The discovery of a Malagasy bothremydid of Maastrichtian age that is nested within the Indian members of the Kurmademydini supports the hypothesis of a connection between Madagascar and the Indian subcontinent that persisted into the late stages of the late Cretaceous.Item Sokatra, a new side-necked turtle (late Cretaceous, Madagascar) and the diversification of the main groups of Pelomedusoides. (American Museum novitates, no. 3728)(American Museum of Natural History., 2011-12-22) Gaffney, Eugene S.; Krause, David W.Sokatra antitra, n. gen. et sp., is a new side-necked turtle from the Maastrichtian (Upper Cretaceous) Maevarano Formation, Mahajanga Basin, northwestern Madagascar. Sokatra antitra is based on a series of incomplete skulls: a partial skull that lacks the premaxillae and some of the basicranium, a partial skull that has a complete ear region and partial basicranium, and other isolated specimens, including dentaries. Although this species exhibits some features of the North African and Brazilian Euraxemydidae, it does not belong to this family, but instead it is the sister taxon of the magnafamily Podocnemidera of Gaffney et al. (2006, 2011). Characters of Sokatra uniting it with the magnafamily Podocnemidera are: quadratebasisphenoid contact, ventral covering of processus interfenestralis of opisthotic, and at least half of prootic covered ventrally. The laterally open foramen jugulare posterius and the distinct accessory ridge on the maxilla are characteristic, but not unique, features shared with members of the Euraxemydidae. The presence of a small wall posterior to the columellae auris and medial to the incisura columellae auris and the formation of the foramen posterius canalis carotici interni by both the prootic and quadrate are unique to Sokatra. In a PAUP analysis using the character matrix from Gaffney et al. (2006), Sokatra resolves as: (Pelomedusidae, Araripemys (Sokatra (Euraxemydidae (Bothremydidae, Podocnemididae)))). The deep phylogenetic roots of Sokatra indicates the presence of its lineage on Madagascar prior to the beginning of the late Cretaceous.