Researchers in Madagascar have recovered jawbones from two of the oldest dinosaurs yet discovered. Dating from between 225 and 230 million years ago, the bones may help to fill in a huge knowledge gap in an era during which early dinosaurs and mammals appeared.
The bones were first discovered in 1996 and it took teams of specialists some years to dig out the jawbones and the remains of eight other prehistoric animals. The researchers from the Field Museum, Chicago, Northern Illinois University, the University of California, Santa Barbara and the Universite d'Antananarivo, Madagascar, write about their work in the current issue of the journal, Science.
The scientists were led to what has been described as a "spectacular" find by a young local man named Mena. The team had entered a remote village on the island and asked whether anyone had ever seen buried bones. "A boy said that his older brother had found some bones," explained Dr Andrew Wyss of UC Santa Barbara. "So we waited around a half-a-day for the brother, Mena, and sure enough, he showed us a hill with a mound of them." One of the fossils will carry Mena's name in recognition of his find.
Paleontologists are puzzled by the period to which the bones have been dated, the Middle to Late Triassic. Reptiles, amphibians and other vertebrates populated the land during the opening of this period, and by its close early dinosaurs and mammals had appeared. However, there is a sparse fossil record to provide clues about what happened in between.
The new bones will help fill in at least a slice of this missing period. The two dinosaurs were prosauro pods, early herbivores with small heads and long necks that could walk on two or four legs. They appear to be older than Herrerasaurus or Eoraptor, the current record holders for dinosaur seniority.
The new fossils are being studied at the Field Museum, but once this work is completed most of them will be returned to Madagascar according to the research team.
"The villagers have been extremely helpful," Dr Wyss said. "They allow us use of their water, access to their land, and are very interested in what we are doing. Plus they have a great eye for fossils."
