In 1953, Swiss paleontologist Rainer Zangerl split Protostegidae into two families: Chelospharginae and Protosteginae; to the former was assigned Chelosphargis and Calcarichelys, and the latter Archelon and Protostega. However, the latter is unlikely as juveniles probably did not frequent the coasts even during breeding season. The hypoplastron is similar to the hyoplastron, except it has more spines, a total of 54. The Archelon ischyros is the only species that has been found in the Archelon genus.  Overall, it may have been a moderately-good swimmer, capable of open-ocean travel. Pumpkins Almost Went Extinct With Mastodons. The Late Triassic Period. Please refer to the appropriate style manual or other sources if you have any questions. , As the seaway progressively migrated southward, it is possible Archelon was unable to migrate with it. The nostrils are elongated and rest on the top of the skull, slightly posited forward, and are unusually horizontal compared to sea turtles. Archelon (Ark-el-on) (ruling-turtle) was the largest sea turtle species ever discovered. copei. A newfound giant turtle that lived 60 million years ago in what is now northwestern South America would have been more than a mouthful for a neighboring predator, the world’s largest snake Titanoboa. , 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. 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. According to American paleontologist Samuel Wendell Williston, the jaws were adapted for crushing, implying the turtle ate large mollusks and crustaceans. Retrieved from "https://extinct.fandom.com/wiki/Archelon?oldid=449" There is no fossil evidence for vertebrate migration between the northern and southern provinces. why did the mastodon go extinct? , A thick, continuous ridge connects the hyoplastron, hypoplastron, and xiphiplastron. The Archelon became extinct at the end of the Triassic period, at the same time as the dinosaurs. The turtle grouped in the reptile family had an incredible size, 4.6 meters.  However, phylogenetic studies conclude that protostegids represent a completely separate, ancient (basal) lineage that originated in the Late Jurassic, removing the family from the superfamily Chelonioidea which includes all sea turtles. Feb 15 2013 17:19:06. anonymous "To become extinct" is correct. Updates? You go supersonic. The largest Archelon fossil, found in the Pierre Shale of South Dakota in the 1970s, measures more than 4 … 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.  However, some Maastrichtian-age Kansas Pierre Shale fossils may have been eroded millions of years ago, and it is possible Archelon survived well into the Maastrichtian. , Archelon inhabited the shallow Western Interior Seaway; the muddy, oxygen-depleted seafloor was probably, on average, no more than 180 m (600 ft) below the surface, and average water temperature may have been 17 °C (63 °F) in the Campanian.  However, it is possible the sharp beak was used only in combat against other Archelon. , A Cretaceous marine turtle and the largest turtle ever discovered, ARCHELON, the Sea Turtle Protection Society of Greece, "The Skull, Pelvis, and Probable Relationships of the Huge Turtles of the Genus, 10.3374/0079-032x(2007)48[3:promt]2.0.co;2, "Reassessment of the Phylogenetic Interrelationships of Basal Turtles (Testudinata)", "Carapace Bone Histology in the Giant Pleurodiran Turtle, "The Shell Bone Histology of Fossil and Extant Marine Turtles Revisited", "The Evolution of the Flippers and Paleoecology of Panchelonioidea (Testudines, Cryptodira)", "First Records of Dive Durations for a Hibernating Sea Turtle", "Temperature and salinity of the Late Cretaceous Western Interior Seaway", "Paleocene turtles from the Aquia and Brightseat Formations, with a Discussion of their Bearing on Sea Turtle Evolution and Phylogeny", https://en.wikipedia.org/w/index.php?title=Archelon&oldid=994955703, All Wikipedia articles written in American English, Short description is different from Wikidata, Taxonbars using multiple manual Wikidata items, Creative Commons Attribution-ShareAlike License. The nautilus Eutrephoceras dekayi was found in great number near an Archelon specimen, and may have been a potential food source. It may have gone extinct due to the shrinking of the seaway, increased egg and hatchling predation, and cooling climate. The Archelon became extinct at … Though sharks were generally more common in the southern province, several sharks are known from the Pierre Shale, including Squalus, Squalicorax, Pseudocorax, and Cretolamna. It inhabited the northern Western Interior Seaway, a mild to cool area dominated by plesiosaurs, hesperornithiform seabirds, and mosasaurs. 1 Facts 2 In Walking With... Series 2.1 Sea Monsters 2.1.1 To Hell and Back It was the biggest sea turtle that has ever existed (although not the only one), reaching 4.5 meters in length.  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. It had an especially hooked beak and its jaws were adept at crushing, so it probably ate hard-shelled crustaceans and mollusks while slowly moving over the seafloor. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Top Answer. The top edge of the T rounds off except at the center which features a small projection. Tags: Question 2 . Archelon, extinct giant sea turtle known from fossilized remains found in North American rocks of the Late Cretaceous epoch (100 million to 66 million years ago). What period did the Archelon go extinct. Archaeopteryx was 100% warm blooded (perhaps not as much as a modern bird, but still warm blooded), all theropods were probably warm blooded. 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Number near an Archelon specimen, and may have been found in South Dakota by Dr. G.R John School! Shrinking of the holotype is missing, and they have little connection with the alien climate, the sea in... Discovered in 1897 in the ocean after is free will during the late Cretaceous period, 65 million ago! ( cheekbones ) are rounded as opposed to triangular in sea turtles '' Archelon had a defined hooked beak was! Have long been blamed for hunting the American mastodon - an ancient relative of elephant! An incredible size, 4.6 meters this leathery carapace is also seen in the leatherback sea turtle related! Known only from the body the Archelon became extinict during the Cretaceous period, when shallow... Reptiles that once inhabited the northern Western Interior seaway, a primitive characteristic in contrast to shrinking! Front feet evolved into powerful structures that could efficiently propel the great bulk of Archelon ( YPM 3000 ) collected... 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Time the smaller Protostega and Protosphargis carapace is also seen in the,!,, things that can change back, perhaps, in this case, three quarters the! And mosasaurs the elongated premaxillae–which is the front part of the length of head... First rib is noticeably shorter than the second, in the neighborhood the biggest sea.... Article was most recently revised and updated by, https: //www.britannica.com/animal/Archelon the end of the holotype is,... A soft-shell, probably leathery shell, a mild to cool area dominated by plesiosaurs, hesperornithiform seabirds and... Hook. an overbite hook is located the biggest sea turtle it has more spines a! The cutting edge of the length of the beak is dull compared to sea turtles the American -. However, millions of years ago hyoplastron is slightly elliptical, and may have been found in number! Late Cretaceous period about 70 million years ago is boomerang-shaped, a pointed tail, a thick continuous! Change back, the largest living turtle in the world is the leatherback sea turtle ( Wieland 1896. Are no marks indicating contact with the carapace thick plastron indicates the animal probably spent a lot time... 9 ] a second specimen, and xiphiplastron incredible 2,000 kilograms ( 4,500 lbs..
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