- Rapetosaurus
Taxobox
name = "Rapetosaurus"
fossil_range=Late Cretaceous
image_width = 290px
regnum =Animal ia
phylum = Chordata
classis = Sauropsida
superordo =Dinosaur ia
ordo =Saurischia
subordo =Sauropodomorpha
unranked_familia =Titanosaur ia
familia =Nemegtosauridae
genus = "Rapetosaurus"
genus_authority = Curry Rogers & Forster, 2004
subdivision_ranks =Species
subdivision =
*"R. krausei" Curry Rogers & Forster, 2004 (type)"Rapetosaurus" is a
genus ofsauropod dinosaur that lived inMadagascar from 70 to 65million years ago , at the end of theCretaceous Period. Only onespecies ("R. krausei") has been identified.Like other sauropods, "Rapetosaurus" was a quadrupedal
herbivore ; it is calculated to have reached lengths of 15metre s (49 ft).Description
"Rapetosaurus" was a fairly typical sauropod, with a short and slender
tail , a very longneck and a huge,elephant -like body. Its head resembles the head of adiplodocid , with a long, narrow snout and nostrils on the top of itsskull . It was an herbivore and its small, pencil-liketeeth were good for ripping the leaves offtree s but not for chewing.It was fairly modest in size, for a
titanosaur . The juvenile specimen measured 8 metres (26 ft) from head to tail, and "probably weighed about as much as an elephant", according to Kristina Curry Rogers. An adult would have been about twice as long (15 meters (49 ft) in length) which is still less than half the length of its gigantic kin, like "Argentinosaurus " and "Paralititan ".Range
During the early part of the Late Cretaceous all groups of sauropods, with the exception of the titanosaurs had gone extinct. The titanosaurs were the dominant herbivores of the Late Cretaceous on the southern continents. Their reign was cut short by the
Cretaceous-Tertiary extinction event , which killed almost all thedinosaur s about 65million years ago .Discovery and naming
The discovery of "Rapetosaurus", known by the single species "Rapetosaurus krausei" (pronounced "rah-PAY-too-SORE-us KROW-sie" and meaning 'Krause's mischievous giant lizard') marked the first time a
titanosaur had been recovered with an almost perfectly intactskeleton , complete withskull . It has helped to clarify some difficult, century-old classification issues, among this large group ofsauropod dinosaur s and provides a good baseline for the reconstruction of othertitanosaur s that are known only from partialfossil ized remains.The discovery was published in 2001 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.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 tailvertebra 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 ofMahajanga . They were recovered from a layer of sandstone known as the Anembalemba Member, which is part of theMaevarano Formation . The rock formation has been dated to theMaastrichtian 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 localUniversite d'Antananarivo . The team leader, David Krause, had 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, andmammal s have been unearthed. Significant finds include:
* The skull of "Majungasaurus ", a large carnivoroustheropod like "Tyrannosaurus ", was discovered in 1996. It is similar to species found inIndia andArgentina , which indicate that land bridges between the fragments of the former supercontinent of Gondwana still existed in the late Cretaceous, far later than was previously believed. The most likely occurrence was a land bridge allowing animals to cross fromSouth America toAntarctica , and then up to India and Madagascar. "(See alsoPolar dinosaurs in Australia .)"
* "Majungasaurus" fossils have also been discovered with teeth marks that clearly come from the same species, making it the first dinosaur known to have practicedcannibal ism.
* "Masiakasaurus " is a new species oftheropod , with very unusual teeth that stick straight out from its jaw.
* A single, 70 million year oldmarsupial tooth. Madagascar was separated by water when the marsupials first evolved in the northern hemisphere, and there are no current species of marsupial on the island, which has revived the idea that colonies of animals might have somehow crossed vast stretches of water.Implications
The titanosaurs are the largest group of sauropods but are poorly represented in the
fossil record . Other groups of sauropods, even small families like thebrachiosaurid s, are known from more complete remains. Until the discovery of "Rapetosaurus", the 30 or sogenera 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 skeleton.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 nostril" sauropods, which include the titanosaurs, thenemegosaurid s and the brachiosaurids). The wholetaxon 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 box-like skulls with the nostrils midway up the snout, like the "Camarasaurus ", but "Rapetosaurus" has a long, low skull, with the nostrils on the top, similar to "Diplodocus". This has allowed genera known only by "Diplodocus"-like skulls (like "Quaesitosaurus " and "Nemegtosaurus " and other nemegtosaurids) to be classified as macronarians rather than inDiplodocoidea .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 titanosaurs.
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
Macalester College , inSt. Paul, Minnesota ) and Catherine A. Forster, an Associate Professor at the Department of Anatomical Sciences of theState University of New York at Stony Brook , inStony 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 RogersThe generic name "Rapetosaurus" is derived from "Rapeto" (see quote above) and "sauros", which is Greek for "
lizard ". The species epithet, "krausei", is named after the team leader of the expedition, David W. Krause.References
* Kristina Curry Rogers, and Catherine A. Forster. 2004. "The skull of "Rapetosaurus krausei" (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar". "
Journal of Vertebrate Paleontology ", 24(1), pages 121–144. "(Abstracts at [http://www.bioone.org/bioone/?request=get-abstract&issn=0272-4634&volume=024&issue=01&page=0121 BioOne] and [http://www.dinodata.org/index.php?option=com_content&task=view&id=7337&Itemid=67 DinoData]
* Kristina Curry Rogers, and Catherine A. Forster. August 2, 2001. "The last of the dinosaur titans: a new sauropod from Madagascar". "Nature" 412, pages 530–534. "(Abstract [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v412/n6846/abs/412530a0_fs.html here] .)"External links
* " [http://www.smm.org/research/Paleontology/Rapeto.php Paleontology News — Rapetosaurus] " from the Science Museum of Minnesota.
* " [http://naples.cc.sunysb.edu/UAff/press.nsf/0/27c07f8d01443df985256a9b00651b11?OpenDocument Stony Brook Paleontologists Discover New Dinosaur and Name It in Honor of One of Their Own] " from SUNY-Stony Brook.
* " [http://www.timeforkids.com/TFK/news/story/0,6260,169874,00.html New Dinosaur Species Found] " from Time for Kids Online.
* " [http://news.nationalgeographic.com/news/2001/08/0801_madagascardino.html Skeleton of New Dinosaur "Titan" Found in Madagascar] " from National Geographic.
* " [http://news.bbc.co.uk/hi/english/sci/tech/newsid_1469000/1469608.stm Dino skull fills knowledge gap] " from the BBC.
* " [http://www.trexmuseum.org/newsalert.html New Madagascar Dinosaur Discoveries] " from the "T. Rex" Museum.
* A [http://www.nsf.gov/od/lpa/news/press/01/pr0161.htm press release] , from the National Science Foundation, including a reconstruction (illustration).
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