Qualitative and quantitative analyses of Middle Eocene odontaspidid shark (Brachycarcharias) from Wadi Garawi area, north Eastern Desert, Egypt

The present study performs various analyses on the fossil shark teeth qualitatively and quantitatively. Fifty-eight fossil teeth were collected from the Middle Eocene deposits exposed at Wadi Garawi area, north Eastern Desert, Egypt. This succession is represented by the Guishi Member of the Observatory Formation, consisting mainly of limestones rich in shark teeth, with fossiliferous marls and sandstone interbeds. Through qualitative analysis, the collected teeth were assigned to three Brachycarcharias species; B. atlasi (Arambourg), B. lerichei (Casier), and B. twiggsensis (Case). In order to discriminate among the different Brachycarcharias species, the ImageJ and MorphoJ software packages were utilized to perform various morphometric analyses, including configuration of distinct landmarks, procrustes superimposition analysis, principal component analysis, and thin plate spline deformation plots. Besides these quantitative analyses, careful qualitative examination highlights considerable variations among the different Brachycarcharias species. In addition, these analyses support that the species Brachycarcharias twiggsensis (Case) can be attributed to a different genus, Tethylamna Cappetta and Case 2016.