Researchers discover the oldest dinosaur fossil

Prehistoric lizards developed 15 million years earlier than expected

As in this drawing, the primordial dinosaur living 243 million years ago may have looked like Nyasasaurus parringtoni. © Natural History Museum, London / Mark Witton
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The dinosaurs probably originated earlier than previously thought. This is indicated by the finding of the oldest known fossil of such a primeval lizard in Tanzania. The 243-million-year-old relics consist of a humerus and six vertebrae and come from the well-dog-sized primordial dinosaur Nyasasaurus parringtoni. This had lived around 10 to 15 million years earlier than any previously known representatives of this group of animals.

The fossil for the first time proves that there were dinosaurs - or a very close relative of them - already in the Middle Triassic, reports the international paleontology team in the journal "Biology Letters". The discovery of the fossil in Africa also indicates that the first dinosaurs originated on the southern part of the primal continent Pangea - from this later formed the land masses of Africa, South America, Australia and the Antarctic.

"For 150 years, it has been suspected that dinosaurs may have been present in the Middle Triassic as well, but clear evidence has not been found so far, " says first-time author Sterling Nesbitt of the University of Washington at Seattle. Although footprints were discovered from this period, which could come from the primeval lizards, but one could not exclude that other animals had left them.

The earliest distinct dinosaur fossils date back to the late Triassic, around 230 million years ago. At that time, however, numerous species of these primordial lizards existed in various regions of the earth. So far it has remained unclear whether the dinosaurs were actually created until the late Triassic and then spread explosively, the researchers say. Now show that their development began earlier and probably went a little slower.

Found and then forgotten

The bones of Nyasasaurus parringtoni were discovered as far back as the 1930s near Lake Malawi in Tanzania, also known as Lake Nyasa. Although a paleontologist in the 1950s had begun to examine the fossil stored in the South Africa Museum in Cape Town closer. His description was never published and the fossil was forgotten. "Only now, 80 years later, we bring it back to light, " says Nesbitt. display

From the dimensions of the humerus and the six fossil vertebrae, paleontologists conclude that Nyasasaurus parringtoni had a shoulder height of about one meter and a tail two to three meters long. He weighed between 20 and 60 kilograms - about as much as a big dog.

Upon further examination of the bones, the researchers found several features typical of early dinosaurs. The arm bone has a characteristic ridge on which the strong muscles of the animal once attached. In addition, the bone tissue is interspersed with disordered cavities, indicating a rapid growth. "The bone tissue is exactly what we would expect for an animal at the base of the dinosaur pedigree, " says Nesbitt (doi: 10.1098 / rsbl.2012.0949).

(Biology Letters, 05.12.2012 - NPO)