April 19, 2013
First New Dinosaur Species Discovered In Almost A Decade – Raises New Questions Of Evolutionary Ancestry
Brett Smith for redOrbit.com - Your Universe Online
A pair of American researchers has announced the discovery of a new species of dinosaur from Madagascar — the first such discovery in almost a decade.
According to a report in the open access journal PLOS ONE, the discovery fills a gap in the island nation´s fossil record and provides clues to the evolutionary history of Madagascar and India, which were part of the same land mass millions of years ago.
The new species which has been dubbed Dahalokely tokana, is between nine and 14 feet long, and lived around 90 million years ago, the report said.“¯Dahalokely is believed to be part of a group of carnivorous dinosaurs called abelisauroids and its name means "lonely small bandit” in the Malagasy language.
"This dinosaur was closely related to other famous dinosaurs from the southern continents, like the horned Carnotaurus from Argentina and Majungasaurus, also from Madagascar," said co-author Joe Sertich, a curator for the Denver Museum of Nature & Science.
Before the discovery of the new species, archeologists had been unable to find Madagascar dinosaur fossils dating from 165 to 70 million years ago, leaving a 95-million-year gap in the fossil record.“¯The new find closes that gap by 20 million years.
"We had always suspected that abelisauroids were in Madagascar 90 million years ago, because they were also found in younger rocks on the island.“¯Dahalokely nicely confirms this hypothesis," said lead researcher Andrew Farke, a curator of paleontology at the Raymond M. Alf Museum of Paleontology in California.
The fossils were discovered in 2007 and 2010, near the city of Antsiranana in northern Madagascar. Researchers uncovered fossilized vertebrae and ribs, and their unique structure allowed for the definitive identification of the specimen as a new species. Signature features like shape of the vertebrae are unlike those found in any other dinosaur, the researchers noted.
The researchers determined the approximate size of Dahalokely by comparing them to other more complete abelisauroid specimens that have either been detailed in literature or extrapolated from published skeletal reconstructions.
“The fossils of“¯Dahalokely are tantalizingly incomplete — there is so much more we want to know,” Farke said. “Was“¯Dahalokely closely related to later abelisauroids on Madagascar, or did it die out without descendents?"
"This just reinforces the importance of exploring new areas around the world where undiscovered dinosaur species are still waiting," Sertich added.
Dahalokely roamed Madagascar while it was still connected to India and adrift in the central Indian Ocean, according to calculations by the researchers. Previous geological studies have shown that India and Madagascar drifted apart around 88 million years ago just after“¯Dahalokely became extinct.
The dates attributed to the new species means that it could be a genetic ancestor of animals that later inhabited both Madagascar and India. However, the researchers pointed out that they do not yet know enough to outline any direct lineages. However, they noted that the bones do have features found in dinosaurs from both Madagascar and India.
In their conclusion, the authors noted that any tenuous connection between Dahalokely and other known animals could be overturned through future work.