Mackerel Sharks of the genus Cretalamna are known from Early Cretaceous to Early Eocene deposits around the world, and are thought to have been ancestral to modern species such as the Great White and Mako, as well as distinctive prehistoric species such as the giant Carcharocles megalodon. Like other fossil Sharks these species are usually only represented by their teeth, which are mineralised and grown and shed throughout their lives, rather than their skeletons, which are made of soft cartilage. Consequently differentiating these Sharks to species level is difficult, and many Late Cretaceous specimens have been assigned to a catch all species, Cretalamna appendiculata.
In a paper published in the journal PeerJ on 8 January 2018, Jun Ebersole of the McWane Science Center and Dana Ehret of the Alabama Museum of Natural History at the University of Alabama and the New Jersey State Museum, describe a new species of Cretalamna from the Late Cretaceous Tombigbee Sand of Alabama.
The new species is named Cretalamna bryanti, in honour of the Bryant family for their support of the University of Alabama, the Alabama Museum of Natural History, and the McWane Science Center. Teeth assigned to Cretalamna have been collected from the Tombigbee Sand for many years, but assigned to Cretalamna appendiculata. Ebersole and Ehret carried out a morphometric analysis, a method that relies on comparing the ratios of different measurements to one-another rather than simply assigning the samples to groups based upon their obvious shape, in order to determine that these specimens did not belong to any previously described species.
Cretalamna bryanti, anterior teeth. (A)-( E) Upper right anterior tooth in (A) oral, (B) basal, (C) mesial, (D) lingual, and (E) labial views. (F)-( J) Upper right anterior tooth in (F) lingual, (G) labial, (H) mesial, (I) oral, and (J) basal views. (K )-(O) Upper left anterior tooth, large morphology, in (K) oral, (L) basal, (M) mesial, (N) lingual, and (O) labial views. (P)-( T) Lower right anterior tooth in (P) lingual, (Q) labial, (R) mesial, (S) oral, and (T) basal views. Scale bars equal 1.0 cm. Ebersol & Ehret (2018).
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