Information AboutRapetosaurus |
| CATEGORIES ABOUT RAPETOSAURUS | |
| cretaceous dinosaurs | |
| dinosaurs of india and madagascar | |
| titanosaurs | |
The discovery of the ''Rapetosaurus'', known by the single species '''''Rapetosaurus krausei''''' (pronounced ''rah-PAY-too-SORE-us KROW-sie'', and meaning "Krause's mischievous giant lizard") marks the first time a Titanosaur has been recovered with an almost perfectly intact skeleton, complete with a matching skull. It has helped sort out some sticky century-old Classification issues among this large group of Sauropod Dinosaur s, and provides a good baseline for the reconstruction of Titanosaur s known only from partial Fossil ized remains. The discovery was published in 1991 by Kristina Curry Rogers and Catherine A. Forster in the scientific journal '' Nature ''. The nearly complete skeleton is that of a juvenile, and partial remains from three other individuals were also recovered. DESCRIPTION The ''Rapetosaurus'' was a fairly typical titanosaur, with a short and slender Tail , a very long Neck , and a huge, Elephant -like body. Its head resembles the head of a Diplodocid , with a long, narrow snout, and nostrils on the top of its Skull . It was an Herbivore , and its small pencil-like Teeth were good for ripping the leaves off Tree s, but not for chewing. It was fairly modest in size, for a titanosaur. The juvenile specimen measured 8 Meter s (26 Feet ) from head to tail, and "probably weighed about as much as an elephant", according to Kristina Curry Rogers. An adult would be about twice as long, or 15 meters (50 feet) in length — which is still less than half the length of its gigantic kin, like the '' Argentinosaurus '' and the '' Paralititan ''. Range Most of the other sauropods, like the '' Brachiosaurus '' and '' Diplodocus '', became extinct in the early Cretaceous . The titanosaurs were the one exception. They evolved on the southern Supercontinent of Gondwana , and grew in numbers and diversity until they became the dominant herbivore of the late Cretaceous. Their reign was cut short by the Cretaceous-Tertiary Extinction Event , which killed almost all the Dinosaur s about 65 million years ago. THE MADAGASCAR DIG :"Only a few of the tail bones were missing." ::—Kristina Curry Rogers The dig uncovered a partial skull (UA 8698, the Holotype specimen), another partial skull, a juvenile skeleton missing only a few tail Vertebra e, and an unrelated vertebra. The juvenile skeleton, in particular, is the most complete titanosaur skeleton ever recovered, and the only one with a head still attached to the body. The fossilized remains were found in the Mahajanga basin in northwest Madagascar , not far from the port city of Mahajanga . They were recovered from a layer of sandstone known as the Anembalemba Member, which is part of the Maevarano Formation . The rock formation has been dated to the Maastrichtian Stage of the late Cretaceous, which means the fossilized bones are about 70 million years old. They were found by a field team from the State University Of New York At Stony Brook with the assistance of the local Universite D'Antananarivo . The team leader, David Krause, has been excavating fossils from the site since 1993. A treasure-trove of bone :"We dug into the hillside, and the more you dug, the more bones we found". ::—Kristina Curry Rogers The Madadgascar location has produced a large number of significant Paleontological discoveries for Krause and his team. As well as dinosaurs, fossils of Fish es, Frog s, Turtle s, Snake s, Crocodile s, Bird s, and Mammal s have been unearthed. Significant finds include:
Implications :"What's been particularly frustrating to paleontologists who study these animals is that we haven't had a clue what a titanosaur skull looks like". ::—Kristina Curry Rogers The titanosaurs are the largest group of sauropods, but they are very poorly represented in the Fossil Record . Other groups of sauropods, even small families like the Brachiosaurid s, are known from more complete remains. Until the ''Rapetosaurus'', each of the 30 or so Genera were represented by just a few bones, a partial skeleton, or a skull. The First Titanosaur , discovered in 1887, is still only known from a partial skull. This has made it difficult to determine not just the relationship between different genera of titanosaur, but even how the titanosaurs are related to other, higher-level groups like the Macronaria ns (the group of "big nosed" sauropods, which include the titanosaurs, the Nemegosaurid s, and the brachiosaurids). The whole Taxon has been used as a dumping ground, with many genera labeled as ''incertae sedis'' (belonging to an unknown group), because not enough is known about them to classify them any further. The ''Diplodocus''-like skull has demonstrated that titanosaur skulls vary more than was previously believed. Most Paleontologist s believed that titanosaurs had boxy skulls with the nostrils on the side, like the '' Camarasaurus '', but the ''Rapteosaurus'' has a long, low skull, with the nostrils on the top, like a ''Diplodocus''. This has allowed genera known only ''Diplodocus''-like skulls (like the '' Quaesitosaurus ''; and the '' Nemegtosaurus '' and the rest of the nemegtosaurids) to be positively classified as macronarians instead of Diplodocidimorph s. Analysis of the rest of the skull and the body has also confirmed what was only previous speculated: That titanosaurs are most closely related to the brachiosaurids. "The discovery of this dinosaur is particularly exciting because it confirms a close relationship between the titanosaurs and brachiosaurs, something that could only be surmised previously," according to Rich Lane, of the National Science Foundation . A complete skeleton can also serve as a baseline when reconstructing other titanosaurs from limited remains. This is the basis for new, revised estimates of the size of the super-giant titanosaurids. CLASSIFICATION The new species, ''Rapetosaurus krausei'', was described in the August 2, 2001 issue of the scientific journal ''Nature'' by Kristina Curry Rogers, then a graduate student under Catherine Forster, and now employed by the Science Museum Of Minnesota and Macalester College , in St. Paul, Minnesota ; and Catherine A. Forster, an Associate Professor at the Department of Anatomical Sciences of the State University Of New York At Stony Brook , in Stony Brook, New York . The ''Rapetosaurus'' is a member of the Nemegtosauridae Family , which is within the unranked Titanosauria taxon. ETYMOLOGY :"Rapeto is the name of a mischievous, mythical Giant in Malagasy Folklore , rather like our Paul Bunyan " ::—Kristina Curry Rogers The genera name ''Rapteosaurus'' is dervived from ''Rapeto'' (see quote above), and ''saurus'', which is Greek for '' Lizard ''. The species epithet, ''krausei'', is named after the team leader of the expedition, David W. Krause. REFERENCES
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