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However, since the sharks’ presence in the fossil record has mostly consisted of isolated teeth, scientists have been left to speculate on what the rest of this ancient predator looked like ...
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 ...
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.
However, viruses are still poorly understood and may have arisen before "life" itself, or may be a more recent phenomenon. Major extinctions in terrestrial vertebrates and large amphibians. Earliest examples of armoured dinosaurs. 195 Ma First pterosaurs with specialized feeding (Dorygnathus). First sauropod dinosaurs.
A team of scientists recently captured the elusive bluntnose sixgill shark, a deep-sea fish that has been on Earth before dinosaurs, on film.
Get excited for the 35th official Shark Week, from July 23 to July 29, with these shark facts.
A possible explanation is an increased competition by sharks, Teleostei, and the first Plesiosauria. Like the dinosaurs, the ichthyosaurs and their contemporaries, the plesiosaurs, survived the Triassic–Jurassic extinction event, and quickly diversified again to fill the vacant ecological niches of the early Jurassic.
In the oceans, the K–Pg extinction killed off plesiosaurs and mosasaurs and devastated teleost fish, [27] sharks, mollusks (especially ammonites, which became extinct), and many species of plankton. It is estimated that 75% or more of all species on Earth vanished. [28]