Open AccessNew choristoderes (Reptilia: Diapsida) from the Upper Cretaceous and Palaeocene, Alberta and Saskatchewan, Canada, and phylogenetic relationships of Choristodera
Author(s) -
GAO KEQIN,
FOX RICHARD C.
Publication year - 1998
Publication title -
zoological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.148
H-Index - 83
eISSN - 1096-3642
pISSN - 0024-4082
DOI - 10.1111/j.1096-3642.1998.tb00580.x
Subject(s) - cretaceous , synapomorphy , paleontology , genus , cladistics , range (aeronautics) , biology , taxon , zoology , clade , phylogenetic tree , biochemistry , materials science , composite material , gene
New choristoderan fossils from the Late Cretaceous and Palaeocene of Alberta and Saskatchewan, Canada, are described: incomplete maxillae and dentaries from the Upper Cretaceous Oldman Formation, Alberta, extend the range of the primitive Cteniogenys from the Jurassic in the North American Western Interior; an incomplete dentary from the Palaeocene Ravenscrag Formation, Saskatchewan, comprises the first occurrence of the crocodile‐like Simoedosaurus in Canada and the earliest record of the genus; well‐preserved skulls and mandibles from the Oldman and Horseshoe Canyon formations, Alberta, document a new species of Champsosaurus and clarify the status of previously known species of the genus. New information about Asian choristoderes supports a Tchoiria‐ ( Ikechosaurus + Simoedosaurus ) relationship, contrary to previous work. Choristoderes share no convincing synapomorphies with either Lepidosauromorpha or Archosauromorpha, but occupy a more basal position within Diapsida, possibly as a sister‐taxon with Neodiapsida (Younginiformes + Sauria).