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Galeocerdo is a genus of ground shark.Only a single species, G. cuvier, the tiger shark, is extant. [1] The earliest fossils date back to the early Eocene epoch, (), around 56–47.8 Million years ago. [2]
All vertebrate jaws, including the human jaw, evolved from early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps the most profound and radical evolutionary step in the vertebrate history". [4] [5] Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct.
Galeocerdo alabamensis is an extinct relative of the modern tiger shark. Nomenclature of this shark has been debated, and recent literature identified it more closely with the Physogaleus genus of prehistoric shark, rather than Galeocerdo. The classification of Physogaleus is known as tiger-like sharks while Galeocerdo refers to
The smalltooth sand tiger or bumpytail ragged-tooth (Odontaspis ferox) is a species of mackerel shark in the family Odontaspididae, with a patchy but worldwide distribution in tropical and warm temperate waters. They usually inhabit deepwater rocky habitats, though they are occasionally encountered in shallow water, and have been known to ...
Physogaleus teeth reach a maximum size that is smaller than that of true tiger sharks, and they lack the heavy serrations typical of Galeocerdo. They are also are more slender and the central cusp can be somewhat twisted toward the crown. This indicates individuals of Physogaleus probably had a diet of bony fish, similar to the living sand ...
Helicoprion is a genus of extinct shark-like [1] eugeneodont fish. Almost all fossil specimens are of spirally arranged clusters of the individuals' teeth, called "tooth whorls", which in life were embedded in the lower jaw. As with most extinct cartilaginous fish, the skeleton is mostly unknown.
This genus consists of a single species, the hooktooth shark, characterized by long, hooked teeth in the lower jaw and no toothless spaces at the midlines of the jaws. The gill slits are very long, the snout is wedge-shaped, and the fins are not falcate. [2] Known fossil species include C. affinis. [3]
Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes).They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and chimaeras.