The fossilized remains of a new, nearly complete longnecked sauropod dinosaur were recently unearthed on the island of Madagascar. The discovery was announced today in the journal Nature by National Science Foundation (NSF)-funded scientists from State University of New York (SUNY), Stony Brook and the Science Museum of Minnesota.
"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," says Rich Lane, program director in NSF's division of earth sciences, which funded the research. "The prolific northern Madagascar dinosaur sites uncovered by the team of scientists continue to shed new and exciting light on Mesozoic reptiles."
The new plant-eating sauropod ("Brontosaurus"-like) dinosaur was discovered in 1995 in northwestern Madgascar, near the port city of Mahajanga, by a field crew from the State University of New York (SUNY) at Stony Brook and the Universite d'Antananarivo.
The specimens found by the team include an adult skull and a nearly complete juvenile skull and skeleton. The scientists, Catherine Forster of Stony Brook and Kristina Curry Rogers of the Science Museum of Minnesota, named the new dinosaur Rapetosaurus krausei (RaPAY-to-SORE-us KRAUSE-eye).
Rapetosaurus lived near the end of the dinosaur age, approximately 70 million years ago in the Late Cretaceous Period. An adult Rapetosaurus approached 50 feet in length, with a small head perched at the end of an elongate neck, and a long, slender tail. It walked on all fours.
Rapetosaurus belongs to a group of sauropod dinosaurs called titanosaurs, the last family of sauropod dinosaurs to evolve. They have been found all around the world and are common in the southern hemisphere. More than 30 kinds of titanosaurs are known, but none have been described that are represented by complete skulls and skeletons. In contrast, nearly every bone in the body of Rapetosaurus is known.
"What's been particularly frustrating to paleontologists who study these beasts is that we haven't had a clue what a titanosaur skull looks like," says Curry Rogers. "Rapetosaurus gives us our first view of a titanosaur from head to tail."
Until now, the lack of crucial skull fossils associated with complete skeletons has made figuring out how titanosaur species are related to one another a daunting task. The skull of Rapetosaurus shows that its nostrils lay on the top of the skull rather than in the front of the snout like a horse or a dog.
While this seems like a very odd arrangement, it is actually similar to that found in the Diplodocus family of sauropods. But Curry Rogers and Forster also discovered that despite this similarity, the rest of the skull and skeleton more closely resembles the Brachiosaurus-like sauropods.
The discovery of the skull of Rapetosaurus showed Curry Rogers and Forster that two enigmatic sauropods from Mongolia (Nemegtosaurus and Quaesitosaurus) are actually titanosaurs, and not, as theorized, more closely related to other sauropod families. Rapetosaurus was key in this resolution, since it provides both a skull and skeleton for comparing titanosaurs (previously only known from skeletons) to these two Mongolian dinosaurs (known only from skulls).
Funding for the Madagascar project was also provided by the National Geographic Society, with additional support from The Dinosaur Society and the Field Museum of Natural History, Chicago.
Program Contact: Rich Lane 703-292-8551 hlane@nsf.gov.
Note: Images available at: http://www.nsf.gov/od/lpa/news/press/01/pr0161.htm
Journal
Nature