Showing posts with label Extinct Now. Show all posts
Showing posts with label Extinct Now. Show all posts
Thursday, October 14, 2010
October 14, 2010 : Enchodus (Extinct)
Enchodus
Enchodus is an extinct genus of bony fish. It flourished during the Upper Cretaceous and was small to medium in size. One of the genus' most notable attributes are the large "fangs" at the front of the upper and lower jaws and on the palatine bones, leading to its misleading nickname among fossil hunters and paleoichthyologists, "the saber-toothed herring". These fangs, along with a long sleek body and large eyes, suggest Enchodus was a predatory species.
The largest-known species of Enchodus is E. petrosus, remains of which are common from the Niobrara Chalk, the Mooreville Chalk Formation, the Pierre Shale, and other geological formations deposited within the Western Interior Seaway and the Mississippi Embayment. Large individuals of this species had fangs measuring 6+ cm in length, though the total body length was only about 1.5 meters, giving its skull an appearance somewhat reminiscent of modern deep-sea fishes, such as anglerfish and viperfish. Other species were smaller, some like E. parvus were only some cm (a few inches) long.
Despite being a formidable predator, remains of Enchodus are commonly found among the stomach contents of larger predators, including sharks, other bony fish, mosasaurs, plesiosaurs and seabirds such as Baptornis advenus.
In North America, Enchodus remains have been recovered from most states with fossiliferous Late Cretaceous rocks, including Kansas, Nebraska, Colorado, Alabama, Mississippi, Georgia, Tennessee, Wyoming, Texas, California, and New Jersey. The taxon is also known from coeval strata in Africa, Europe, and southwest Asia. Enchodus survived the Cretaceous–Tertiary extinction event and persisted at least into the Eocene. It was found all over the world.
Wednesday, June 30, 2010
June 30, 2010 : Helicoprion (Extinct)
Helicoprion
Helicoprion ("Spiral Saw") was a long-lived genus of shark-like cartilaginous fish that first arose in the oceans of the late Carboniferous 280 million years ago, survived the Permian-Triassic Extinction Event, and eventually went extinct during the early Triassic some 225 million years ago.
The only fossils known are the teeth, which were arranged in a fantastic "tooth-whorl" strongly reminiscent of a circular saw. It was not until the discovery of the skull of a relative, Ornithoprion, that it was realized that the tooth-whorl was in the lower jaw. The tooth-whorl represented all of the teeth produced by that individual in the lower jaw, in that as the individual grew, with the older, smaller teeth being moved into the center of the whorl by the appearance of larger, newer teeth. Comparisons with other eugenodontids suggest that Helicoprion may have grown up to 10-15 ft long.
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