Garden City (dpa) – The exponential growth of dinosaurs has evolved independently of one another more frequently than previously thought. According to a new study, these giant animals originated in 36 lineages with different characteristics and ecological niches over a period of 100 million years. In his study, Michael Dimmick of Adelphi University in Garden City (USA) used measurement data from fossil leg bones, which he calculated the evolution of body mass for nearly 200 dinosaurs. Presents the findings in the journal “Current Biology.”
All of the dinosaurs studied belonged to the group of sauropods, which gave rise to such famous genera as Brontosaurus, Brachiosaurus, and Diplodocus. Sauropods are characterized by a massive body on thick legs, a very long tail, and a neck with a relatively small head. “It was previously believed that sauropods evolved their exceptional size independently several times in their evolutionary history, but with the new analysis we now know that this number is much higher,” Demic said in a statement from his university.
As a maximum for giants, the researcher chose the body mass of the largest mammal that ever lived on Earth: the mammoth. “These larger sauropod species were ecologically diverse, with differently shaped teeth and heads, and differently proportioned bodies, which suggests that they occupied the ‘large body’ niche somewhat differently,” Dimmick said.
There are also no features that distinguish those sauropods that exceed the size of land mammals, the author of the study writes. Climate probably plays a minor role in evolution, as there is no relationship between global mean temperature and body mass in sauropods. Hence the new research question as to why some strains developed giants while others did not.
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