copei. Retrieved from "https://extinct.fandom.com/wiki/Archelon?oldid=449" Wieland in 1895 and described by him the following year (Wieland, … , The carapace, in life, probably featured a row of ridges along the midline over the chest region, perhaps totaling in seven ridges, with each ridge peaking at either 2.5 or 5 cm (1 or 2 in). 75, 568 pp, 113 pl. Archelon is an extinct marine turtle from the Late Cretaceous, and is the largest turtle ever to have been documented, with the biggest specimen measuring 460 cm (15 ft) from head to tail, 400 cm (13 ft) from flipper to flipper, and 2,200 kg (4,900 lb) in weight. The spongy makeup is similar to the bones seen in open-ocean going vertebrates such as dolphins or ichthyosaurs, and was probably also an adaptation to reduce overall weight. Established in 1983 in recognition of the extinct species, the primary objective of Archelon (the Sea Turtle Protection Society of Greece) is to … Dinosaurs weren't the only animals that grew to immense sizes during the late Cretaceous period. The hyoplastron is slightly elliptical, and grows thinner as it gets farther from the center before the spines erupt. Hay, O. P. 1908. The plastron, as a whole, is thick, and measures, in a specimen described in 1898, 210 cm (7 ft) in length.  Brigitta is estimated to have lived to 100 years, and may have died while partially covered in mud brumating–a state of dormancy–on the ocean floor. Feb 15 2013 17:19:06. anonymous "To become extinct" is correct. There … Combined with the alien climate, the hunting by humans led to the eventual extinction of the woolly mammoths. It is known only from the Dakota Pierre Shale and has one species, A. ischyros. The spines grow thick and narrow towards their middle portion. The plates of the carapace are mostly uniform in dimensions, with the exception of the two pairs of plates corresponding to the eighth thoracic vertebra which are smaller than the others, and the pygal plate closest to the tail which is larger.  Its tail likely had a wide range of mobility, and the tail is thought to have been able to bend at nearly a 90° angle horizontally. Arrival of Humans. , A thick, continuous ridge connects the hyoplastron, hypoplastron, and xiphiplastron.  In the absence of firmly jointed neck and pleural plates, the skin over the carapace was probably thick, strong, and leathery in order to compensate and properly support the shoulder girdle. The nautilus Eutrephoceras dekayi was found in great number near an Archelon specimen, and may have been a potential food source. How and When Did the Dodo Go Extinct? So why did they finally go extinct… The outward side is slightly convex and bends somewhat away from the body. These animals can no longer be found today, as they became extinct a few million years ago, and are so ancient that they came to cohabit with the dinosaurs. It inhabited the northern Western Interior Seaway, a mild to cool area dominated by plesiosaurs, hesperornithiform seabirds, and mosasaurs. The Late Mesozoic Period . Wieland, G. R. 1902. , In 2002, a fifth specimen, a partial skeleton, was discovered from the Pierre Shale of North Dakota along the Sheyenne River near Cooperstown. Much of the length of the head derives from the elongated premaxillae–which is the front part of the beak in this animal–and maxillae. The largest Archelon fossil, found in the Pierre Shale of South Dakota in the 1970s, measures more than 4 … , As the seaway progressively migrated southward, it is possible Archelon was unable to migrate with it. , In 1900, Wieland described a second species, A. marshii, from remains collected in 1898 by American paleontologist Othniel Charles Marsh, to whom the species name refers, on the basis that the shell underside (plastron) was thicker and the humeri were straighter. The carapace may have featured a row of small ridges, each peaking at 2.5 or 5 cm (1 or 2 in) in height. What is the size of the biggest sea turtle?  Other large predatory fish include ichthyodectids such as Xiphactinus. Because of this, scientists believe the k … , A turtle plastron, the underside, comprises, from head-most to tail-most, the epiplastron, the entoplastron, which is small and wedged in between the former and the hyoplastron, then, following, the hypoplastron, and finally the xiphiplastron.  Protostegidae is more-or-less absent in Maastrichtian deposits, the latest Cretaceous, and probably died off due to a cooling trend which other turtles were able to survive due to some thermoregulatory capabilities. The turtle grouped in the reptile family had an incredible size, 4.6 meters. In 1914, he suggested that the abundant, thin-shelled, bottom-dwelling Cretaceous bivalves–some exceeding 120 cm (4 ft) in diameter–would have easily been able to sustain Archelon.  Stretch marks on the limb bones indicate fast growth, with similarities to the leatherback sea turtle, the fastest growing turtle known, whose juveniles have an average growth rate of 8.5 cm (3.3 in) per year.  Overall, it may have been a moderately-good swimmer, capable of open-ocean travel. The second to fifth ribs, in the holotype, originate with a thickness of 2.5 cm (0.98 in) and terminate with around 4 to 5 cm (1.6 to 2.0 in) in thickness. The Archelon ischyros is the only species that has been found in the Archelon genus. I just changed it to beak User:Dunkleosteus77 |push to talk 04:41, 28 December 2018 (UTC) You show the species Inoceramus steenstrupi (misspelled "steenstrup"), but did this exact species live with Archelon, or another species of the genus? He named it Archelon ischyros, genus name from the Ancient Greek ἀρχη- arkhe- "first/early," χελώνη chelone "turtle," and species name from ἰσχυρός ischyros "mighty" or "powerful".  Conversely, the large flipper-to-carapace ratio of protostegids and the similarly large flipper spread, like that of the predatory cheloniid loggerhead sea turtle (Caretta caretta), combined with a broad body, indicate they could have pursued active prey, though they probably could not have sustained high speeds. The last 19 spines are flat. This is indicated by the similarity of the humerus/arm and hand/arm ratios of it and cheloniids, which are known to have poor development of the limbs into flippers and a preference for shallow water. The second to fifth ribs project at a right angle from the midline, and, in the holotype, each measure 100 cm (3.3 ft) in length. Let us know if you have suggestions to improve this article (requires login).  Wieland placed it into the family Protostegidae, which included at the time the smaller Protostega and Protosphargis. Conversely, the beak may have been adapted for shearing flesh, and it might have been able to target larger fish and reptiles, as well as soft-bodied creatures, similar to the leatherback sea turtle, such as squid and jellyfish. 2 meters (6.5 ft) of length, while the heaviest recorded animal weighed around 650 kg (1,430 lb). Carnegie Institution of Washington, Publication No. , Archelon probably had weaker arms, and thus less swimming power, than the leatherback sea turtle, and so did not frequent the open ocean as much, preferring shallower, calmer waters. The first specimen of Archelon (YPM 3000) was collected from the Campanian-age Pierre Shale of South Dakota (a geological formation dated to 80.5 million years ago)by Dr. G.R. It was a seagoing turtle, related to present day Leatherback Sea Turtles. , Five neck vertebrae were recovered from the holotype, and it probably had eight in total in life; they are X-shaped, procoelous–concave on the side towards the head and convex on the other–and their thick frame indicates strong neck muscles. The prehistoric Archelon ischyros had paddle-like legs that served as flippers, so the …  Unlike the carapace, it features striations throughout. Humans have long been blamed for hunting the American mastodon - an ancient relative of the elephant - to extinction. About Archelon . The top edge of the T rounds off except at the center which features a small projection. It was seen floating in the ocean after is free will during the Cretaceous period, 75 millions years ago. The hypoplastron is similar to the hyoplastron, except it has more spines, a total of 54. Wieland in 1895 and described by him the following year (Wieland, 1896). The nostrils are elongated and rest on the top of the skull, slightly posited forward, and are unusually horizontal compared to sea turtles. It can now fight a variety of dinosaurs because of its improved damage and decent health with co…  The latter is now in the family Cheloniidae. Archelon (from Greek αρχελών meaning ruler turtle) is a genus of extinct sea turtles, the largest that have ever been documented. Archelon is an extinct genus of marine turtle that lived during the late Cretaceous period about 70 million years ago. Top Answer. Extinction sucks. SURVEY .  The Pierre Shale's invertebrate assemblage includes a variety of mollusks, namely ammonites–from the Pierre Shale Placenticeras placenta, Scaphites nodosus, Didymoceras, and Baculites ovatus–bivalves–such as the giant Inoceramus– the squid-like belemnites, and nautilus. Its fossils have been found in various US states, especially South Dakota and Wyoning (during this period, much of North America was covered by a shallow sea). "Extinct" is a latinized past participle of the verb "To … Corrections? This entepiplastron is T-shaped, as opposed to the Y-shaped entoplastrons in other turtles. , The holotype measures 352 cm (11.5 ft) from head to tail, with the head measuring 60 cm (2 ft), the neck 72 cm (2.4 ft), the thoracic vertebrae 135 cm (4.4 ft), the sacrum 15 cm (0.5 ft), and the tail 70 cm (2.3 ft). The Archelon became extinct at … It was a very slow mover and was seen drifting along the sea coast in search of food. Wieland in 1895 and described by him the following year (Wieland, 1896).  The xiphiplastron is boomerang-shaped, a primitive characteristic in contrast to the straight ones seen in more modern turtles. The archelon is 4.5 meters (15 ft) from head to tail and 5 meters (16’6″) wide from flipper to flipper. Answer. Debated hotly by biologists, the dodo went extinct at the end of the seventeenth century for three possible reasons, or some combination of them. turtle ever known to exist and it lived at the end of the Cretaceous. For the most part dinosaurs were probably not a threat, as assuming Archelonlaid eggs like turtles do today, it would only Archelon had a soft-shell, probably leathery shell, a pointed tail, a narrow skull, and an overbite. The jugal bones (cheekbones) are rounded as opposed to triangular in sea turtles. Razzi was a grade five kid in St. John XXIII School. 1 Facts 2 In Walking With... 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