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An analysis of a partially complete tail fin fossil shows that Cretoxyrhina had a lunate (crescent-shaped) tail most similar with modern lamnid sharks, whale sharks, and basking sharks. The transition to tail vertebrae is estimated to be between the 140th and 160th vertebrae out of the total 230, resulting in a total tail vertebral count of 70 ...
Stethacanthidae is an extinct family of prehistoric sharks. [1] It is estimated to have existed approximately between 380 and 300 million years ago. Members of this family are noted for their peculiar dorsal fin.
Xenacanthida (or Xenacanthiformes) is an order or superorder of extinct shark-like chondrichthyans (cartilaginous fish) known from the Carboniferous to Triassic. They were native to freshwater, marginal marine and shallow marine habitats. [1] Some xenacanths may have grown to lengths of 5 m (16 ft). [2]
Shark bite marks have been seen on coelacanths; sharks are common in areas inhabited by coelacanths. [66] Electrophoresis testing of 14 coelacanth enzymes shows little genetic diversity between coelacanth populations. Among the fish that have been caught were about equal numbers of males and females. [8]
Sharks could be facing extinction over the next couple of decades. Human interference is largely to blame for the species interference. Overfishing of sharks has increased as the global demand has ...
The shark was an opportunist and piscivorous, and it would have also gone after smaller fish and other sharks. [52] Many whale bones have been found with deep gashes most likely made by their teeth. [ 28 ] : 75 Various excavations have revealed megalodon teeth lying close to the chewed remains of whales, [ 28 ] : 75 [ 30 ] and sometimes in ...
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.
Some of them make mistakes," said Gavin Naylor, director of the Florida Program for Shark Research. Hardly a fair fight between humans and shark Worldwide, humans kill about 80 million sharks and ...