Discovery of oldest dinosaur bones reported in Science

October 20, 1999

A team of paleontologists has discovered jaws from two of the oldest dinosaurs ever discovered, and the remains of eight other prehistoric animals, in a rich bed of fossils in Madagascar, providing a 'time capsule' from the earliest days of dinosaurs and mammals and illuminating scientific understanding of the mid-late Triassic Period. The findings are reported in the October 22 issue of Science.

"We have discovered a spectacular new fauna of this age in southwest Madagascar," said Andre Wyss, associate professor of geology at the University of California, Santa Barbara, and co-leader of the research team. "It includes the fragmentary remains of two plant eating dinosaurs, prosauropods, about the size of a new-born calf, which are not only the earliest dinosaurs known from the island, but probably the earliest dinosaurs known from anywhere in the world."

"This fauna also includes spectacular, close mammal relatives -- mammal-like reptiles," said Wyss. "These are the first fossils of their kind known from Madagascar. Their preservation is superb, rivaling that of anything in the world."

This discovery is just the tip of the iceberg, according to Wyss. "A wealth of bones is pouring out of our quarries," he said. "Once these get cleaned up, we have no doubt that we'll know a great deal more about all of these animals, plus many others. There should be meat-eating dinosaurs present, as well as a host of other novel animals."

To establish the relative ages, scientists must look to what other kinds of fossils are found in association with the dinosaurs. "The Malagasy finding is unique in containing various kinds of animals -- such as certain non-dinosaurian reptiles and mammal relatives -- found elsewhere only in more ancient deposits, and thus lacking dinosaurs," said Wyss.

"Also, the Malagasy fauna lacks other, presumably younger, forms usually found alongside the earliest dinosaurs," he said. "The co-occurrence of dinosaurs and these more ancient kinds of animals -- as well as the non-occurrence of younger groups -- argues for the antiquity of the dinosaurs in this deposit."

Wyss explained that of the various early dinosaur sites known worldwide, it has been possible to directly date, by radioisotopic means, only one of them, the one from Argentina, which is roughly 227 million years old. "Our Malagasy fauna and its dinosaurs are possibly as much as 5 million years older, but all that we can say at this point is that all indications point to its being distinctly older than 227," he said.

The fossils are from a period that has long been a puzzle for paleontologists, the Middle to Late Triassic (225 to 230 million years ago.) At the opening of this period, a variety of reptiles, amphibians, and other vertebrates populated the land. By its close, early dinosaurs and mammals had appeared, but a sparse fossil record has left scientists with few clues about what happened in between.

The prosauropods, herbivores with small heads and long necks, could walk on two or four legs. These primitive dinosaurs either shared a common ancestor with, or were themselves ancestors to, the mighty sauropod dinosaurs that evolved later, such as Apatosaurus.

The five pre-mammalian animals that the researchers discovered should also shed light on the currently murky picture of the origins of the first true mammals. For example, an essential question is how this line of large, cold-blooded 'mammal-like' reptiles evolved into small warm blooded mammals, many of which then evolved to much larger sizes once again, following the extinction of the dinosaurs.

The paleontologists also expect that their find will provide clues about how the breakup of the supercontinent Pangaea, which began in the Triassic, affected the course of evolution.

"There were critical evolutionary events occurring in the Triassic, in response to climate changes and the beginning of the break-up of the supercontinent Pangaea, but we haven't had a good record of them until now," said J. J. Flynn of the Field Museum in Chicago.

The fossils were discovered by John Flynn, of the Field Museum in Chicago, J. Michael Parrish, of the Northern Illinois University, Berthe Rakotosamimanana, of the Universite d'Antananarivo in Madagascar, William Simpson of the Field Museum, and Robin Whatley and Andre Wyss, of the University of California, Santa Barbara.
Editors: Photographs of the fossils and the team are available. B-roll is also available. See sidebar story, 'A Tale of Finding the Oldest Dinosaur Fossils.'

"These discoveries from the Triassic of Madagascar provide an extremely important glimpse into a very poorly known chapter in the evolutionary history of dinosaurs and other backboned animals." "These new dinosaurs from Madagascar are among the earliest known from anywhere in the world. This discovery promises to fill a major gap in our understanding of the origin of mammals, dinosaurs, and their relatives. There have been precious few places where good fossils have been preserved. The new sites in Madagascar are exceptional in that they contain a diverse group of Triassic creatures from a pivotal stage in evolution." "These exciting new finds from the Triassic of Madagascar extend the record of prosauropod dinosaurs back much further than previously known. The cynodonts are some of the best specimens I have ever seen. They will be very important in working out how these close relatives of mammals were related to one another and how they were distributed across the supercontinent of Pangaea." "Early dinosaurs and their contemporaries have long been known from only small areas in South Africa, Argentina, and Brazil. The Isalo fossils from Madagascar may win the prize for being the oldest known dinosaurs. And what beautiful fossils they are -- the quality of preservation of some specimens is remarkable."

University of California - Santa Barbara

Related Dinosaurs Articles from Brightsurf:

Ireland's only dinosaurs discovered in antrim
The only dinosaur bones ever found on the island of Ireland have been formally confirmed for the first time by a team of experts from the University of Portsmouth and Queen's University Belfast, led by Dr Mike Simms, a curator and palaeontologist at National Museums NI.

Baby dinosaurs were 'little adults'
Paleontologists at the University of Bonn (Germany) have described for the first time an almost complete skeleton of a juvenile Plateosaurus and discovered that it looked very similar to its parents even at a young age.

Bat-winged dinosaurs that could glide
Despite having bat-like wings, two small dinosaurs, Yi and Ambopteryx, struggled to fly, only managing to glide clumsily between the trees where they lived, according to a new study led by an international team of researchers, including McGill University Professor Hans Larsson.

Some dinosaurs could fly before they were birds
New research using the most comprehensive study of feathered dinosaurs and early birds has revised the evolutionary relationships of dinosaurs at the origin of birds.

Tracking Australia's gigantic carnivorous dinosaurs
North America had the T. rex, South America had the Giganotosaurus and Africa the Spinosaurus - now evidence shows Australia had gigantic predatory dinosaurs.

Ancient crocodiles walked on two legs like dinosaurs
An international research team has been stunned to discover that some species of ancient crocodiles walked on their two hind legs like dinosaurs and measured over three metres in length.

Finding a genus home for Alaska's dinosaurs
A re-analysis of dinosaur skulls from northern Alaska suggests they belong to a genus Edmontosaurus, and not to the genus recently proposed by scientists in 2015.

Can we really tell male and female dinosaurs apart?
Scientists worldwide have long debated our ability to identify male and female dinosaurs.

In death of dinosaurs, it was all about the asteroid -- not volcanoes
Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers.

Discriminating diets of meat-eating dinosaurs
A big problem with dinosaurs is that there seem to be too many meat-eaters.

Read More: Dinosaurs News and Dinosaurs Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to