Megalolamna Shimada, Chandler, Lam, Tanaka & Ward, 2017

Pollerspöck, Jürgen & Shimada, Kenshu, 2024, The first recognition of the enigmatic fossil shark genus Megalolamna (Lamniformes, Otodontidae) from the lower Miocene of Europe and M. serotinus (Probst, 1879) as the newly designated type species for the genus, Zitteliana 98, pp. 1-9 : 1-9

Genus Megalolamna Shimada, Chandler, Lam, Tanaka & Ward, 2017

Type species.

Otodus serotinus Probst, 1879 , Kodelsberg (E Baltringen), Baden-Württemberg ( Germany).

Emended diagnosis.

Lamniform differing from all known species of otodontids by the following combination of characters: tooth consisting of a sharply-pointed, relatively tall, triangular main cusp, in anterior or anterio-lateral teeth one prominent pair of triangular lateral cusplets, in posterior teeth sometimes a second pair of small, secondary cusplets and strongly bilobed root; main cusp erect, in anterior teeth slightly inclined distally, or gently curved distally, in posterior teeth clearly inclined distally; lingual crown face very convex without ornamentation; labial crown face flat or subtly convex except center of base with weak depression; height and width of each lateral cusplet nearly equal with tendency to point outward; both mesial and distal cutting edges of main cusp and lateral cusplets smooth and razor-like, and continuous from apex to base; main cusp and lateral cusplets nearly erect to gently curved lingually; concave crown base and distinct, chevron-shaped tooth neck on lingual face characterized as a bourlette covered with thin enameloid layer; prominent tooth neck also on labial face in tall teeth, forming rounded ledge with thin enameloid layer that grades into enameloid of main cusp and lateral cusplets; bilobed root with rounded basal tips and moderately tight basal concavity in between; root overall robust but particularly at lingual protuberance that generally exhibits one or two prominent and a few smaller nutritive foramina; root width slightly wider than total crown width; osteodentine tooth histology ( Shimada et al. in press; this study).