Durnonovariaodus maiseyi: A new species of Hybodont Shark from the Upper Jurassic Kimmeridge Clay Formation of Dorset, England.
[sciencythoughts.blogspot.com]
The Hybodonts were a distinctive group of Sharks, which first appeared in the Late Devonian and persisted until the end of the Cretaceous, reaching their maximum diversity in the Triassic and Jurassic. They were the sister group to the Elasmobranchs (the group which includes all modern Sharks and Rays), and had a distinctive morphology with two dorsal fins supported by heavily ornamented spines exhibiting numerous retrorse denticles arranged along the posterior midline, the males in addition having a single or double pair of cephalic spines each with a trifid base carrying a prominent hook-shaped spine on the skull posterior to the orbit. Like other Shark groups, living and extinct, Hybodonts continuously produced and shed teeth throughout their lives, but had a skeleton comprised entirely of cartilage, resulting in an extensive fossil record based upon disarticulated teeth, but relatively few body skeletons, making understanding the taxonomy of the group difficult.
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