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Hyposaurus (Dyrosauridae, Crocodyliformes) from Upper Cretaceous of Sudan



Ben Creisler
bcreisler@gmail.com

A new paper:

Khalaf Allah O. Salih, David C. Evans, Robert Bussert, Nicole Klein,
Mutwakil Nafi & Johannes Müller (2016)
First record of Hyposaurus (Dyrosauridae, Crocodyliformes) from the
Upper Cretaceous Shendi Formation of Sudan.
Journal of Vertebrate Paleontology (advance online publication)
DOI:10.1080/02724634.2016.1115408
http://www.tandfonline.com/doi/full/10.1080/02724634.2016.1115408



We describe a new record of the dyrosaurid crocodyliform genus
Hyposaurus, from the ?Campanian–Maastrichtian Shendi Formation of
Sudan, based on a partial mandibular symphysis, two posterior portions
of the upper jaw, and a fused frontal bone, all belonging to a single
individual. The material can be assigned to Hyposaurus on the basis of
the elliptical shape of the mandibular symphysis (wider than high) and
the overall flat shape of the mandible. At the same time, the fossil
material differs from other species of Hyposaurus in having (1) an
enlarged eighth alveolus of the dentary relative to the other alveoli;
(2) a reduced interalveolar space between the ninth and tenth alveoli;
and (3) a prominent ridge and groove sculpturing on the dorsal side of
the mandible along the symphyseal region. However, due to the
fragmentary nature of the material, we refrain from drawing any
higher-resolution taxonomic conclusions. The occurrence of Hyposaurus
within the Shendi Formation represents the first record of this genus
from the Late Cretaceous of Africa and potentially extends its
temporal range to the Campanian. Whereas this occurrence in the Late
Cretaceous of Sudan supports previous hypotheses of an African origin
for Hyposaurus, more complete material is needed for evaluating these
hypotheses in a phylogenetic framework. We also wish to stress that
the genus Hyposaurus requires detailed revision.