A study of Crocodyliforms from the Upper Cretaceous Strata of the Shendi Formation, north central Sudan: Paleoecological and Paleobiogeographical Implications

Abstract

ABSTRACT Paleontological investigation has been conducted in the area northwest of Shendi town to study the crocodyliforms with implication for paleoecology and paleobiogeography. Numerous Crocodyliformes remains have been recovered from the Upper Cretaceous strata of the Shendi Formation, north central Sudan. Two taxa have been found in these deposits, Dyrosauridae and Crocodylia indet. Among dyrosaurids, the occurrence of Hyposaurus within the present material has been noted, and reported for the first time in the Late Cretaceous of Africa. The identification of the dyrosaurids from the Shendi Formation was based on a partial mandible, premaxilla fragment, frontal, and referred postcrania. The mandible has a reduced seventh alveolus which is a diagnostic character of Dyrosauridae. Although the present materials differ from the previously known Hyposaurus, we choose not to erect a new taxon at this time, since it needs to be catalogued. Hopefully, that will happen very soon to introduce a new species. Due to the lack of diagnostic features of some other remains, they were considered herein as Crocodylia indet. since no further classification can be made at this level. Based on paleontological and sedimentological evidences, an estuarine setting has been assigned to the Shendi Formation. The present record of Hyposaurus within the Shendi Formation extends the temporal range of this genus to Campanian, which may represent the oldest so far known record in the world. The previous hypotheses of the paleobiogeography and dispersal of dyrosaurids especially, Hyposaurus has been discussed and a tentative dispersal in this study has also been proposed. v|1|