Dinosaurs never had a rapid evolution and they evolved slowly. This notion goes against previous theories that talk about a sudden surge in evolution.
This new fact has been reinforced by the discovery of fossils in Brazil where two small dinosaurs and a lagerpetid were found together. The latter is a precursor of dinosaurs.
According to scientists, the discovery is unique as it is the first time a dinosaur and lagerpetid were found together, giving proof that they lived side by side during the early phase of dinosaur evolution.
Published in the Nov. 10 issue of the journal Current Biology, the study draws the conclusion that dinosaurs and their precursors coexisted nicely and the evolution process had been gradual.
"We now know for sure that dinosaurs and dinosaur precursors lived alongside one another and that the rise of dinosaurs was more gradual, not a fast overtaking of other animals of the time," said Max Langer, a paleontologist at the University of Sao Paulo in Brazil.
The Carnian Santa Maria Formation, from where the fossils of lagerpetid (Ixalerpeton) and Saurischian dinosaur (Buriolestes) were spotted, is an old rock formation with an approximate age of 230 million years.
Affirming that the animals were contemporaries during the formative stages of dinosaurs' evolution, the scientists reiterated that the lagerpetid specimen had all the supporting features - skull, forelimb elements, associated vertebrae and scapular - to assert this.
Their tooth also bore evidence that the early dinosaurs ate "all kinds of small animals, but most probably not plants."
As dinosaurs acquired their characteristic anatomical traits gradually, it follows that Buriolestes must have been the oldest known Sauropodomorpha - the long-necked dinosaurs.
Noting the two animals have filled important gaps in the evolutionary history of dinosaurs' anatomical features, the researchers are now using CT scans to come up with more in-depth descriptions of the animals' anatomy. They are planning to obtain a more specific radio isotopic date on the oldest rocks where dinosaurs have been found while being on the lookout for more Triassic fossils.
Mud Dragon Fossils In China
Meanwhile, a dinosaur fossil discovery at a building site in southern China has given scientists vital clues to a family of creatures that thrived immediately before the species was wiped out.
Naming the bird-like species "Mud Dragon," the scientists said it was lying with wings outstretched. They believe the creature must have died after having been stuck in the mud about 70 million years ago.
Bearing the scientific name Tongtianlong limosus, the scientists said the two-legged animal was part of a group of feathered dinosaurs known as oviraptorosaurs.
They are mainly distinguished by crests of bone on the heads that are used in luring mates and attacking rivals.