by Fred Bervoets
 

A team of paleontologist of the Field Muesum have discovered what appear to be the oldest dinosaur fossils ever found in a 225 to 230 million years old (from Middle to Late Triassic) layer in Madagascar. The fossilized remains consists of jaw bones from two unknown plant-eating prosauropod dinosaurs.

The paleontologists of the Field Museum where working in Madagascar during four separate expeditions from 1996 to 1999, the team discovered the exquisitely preserved remains of eight other prehistoric animals of the same age, providing a freezeframe picture of life during the earliest days of dinosaurs and mammals - a picture that has been largely obscured until now.

The fossils were found by John J. Flynn, MacArthur Curator and Chair of the Department of Geology at The Field Museum; William F. Simpson, Collections Manager, Fossil Vertebrates, The Field Museum; J. Michael Parrish, of Northern Illinois University; Berthe Rakotosamimanana, of the Université d\'Antananarivo in Madagascar; and Robin Whatley and Andrew Wyss of the University of California at Santa Barbara.

According to Flynn this project is only beginning to fill in huge gaps in the fossil record of Madagascar that was to be thought having a poor fossil record but now is turning out to be a treasure trove. Previously, radioisotope dating has shown the oldest known dinosaurs, Herrerasaurus and its contemporaries to be just under 228 million years old.

The rock layers at the Madagascar sites have not yet yielded the right minerals for radioisotope dating. But judging from the anatomical details of the fossils, two of the animals (one a parrot-beaked reptile, the other an early relative of mammals) appear to be more primitive cousins to similar animals already known to be younger than 228 million years old.

Because the Madagascar record is so far lacking fossils of aetosaurs - small armored reptilian herbivores that were abundant beginning about 228 million years ago the scientists believe the newly found fossils were even more ancient thats why Flynn and the other team members concluded that their find is probably closer to 230 million years old, which would make the two new prosauropods the oldest dinosaurs ever discovered.

Professor James Hopson, Professor, Department of Organismal Biology and Anatomy, and Committee on Evolutionary Biology (CEB), University of Chicago said that these exciting new finds extend the record of prosauropod dinosaurs back much further than previously known.

None of the new species has been officially named yet but geologist Andrew Wyss of the University of California at Santa Barbara, who worked on the study, said some of the names would honor local residents who found the fossil bed.

Earlier discoveries on Madagascar are not from the Triasic period.

Bothtrospondylus magagascariensis Jurassic Middle

Lapparentosaurus magagascariensis Jurassic Middle

Majungasaurus crenatissimus Cretaceous Late

Majungtholus atopus Cretaceous Late

Stegosaurus madagascariensis Cretaceous Late

Titanosaurus madagascariensis Cretaceous Late .

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