not Tamiobatis (Williamns 1998; Late Devonian; CMNH 9280) was considered a new specimen of Tamiobastis vetustus, but here nests with Isurus, the mako shark. The pointed teeth appear to be out of scale.

Ptychodus sp (Agassiz 1837 Late Cretaceous) was a large shark with gently rounded, pavement stone, crushing teeth. Until recently only the teeth and a lower jaw were known. In the LRT Ptychodus is close to CMNH 9280 specimen (above).

Carcharodon charcharias (Smith 1838, originally Squalodon carcharias Linneaus 1758, up to 5.8m) is the extant great white shark, here a relative to Isurus, the mako shark.

Isurus oxyrinchus (Rafinesque 1810; 3.2m in length) is the extant shortfin mako shark here nesting with the sturgeon, Pseudoscaphirhynchus, contra tradition. Here the nasal is extended to form a rostrum. The lacrimal, premaxilla, maxilla, jugal, squamosal and quadrate are all fused together. The postorbital is fused to the postfrontal. A deep valley divides the skull. The orbit is confluent with the lateral temporal fenestra. The premaxillary teeth are posteriorly oriented. The jugal produced a lateral flange for increased muscle attachment. The skeleton is cartilaginous.

Photo copyright © Sebastian Enault, originally published by Science Connected and used with permission. https://www.gotscience.org/2015/12/preserving-soft-skeleton-backs-without-bones/ Bone colors added here.