Dinosaurs survived 2 mass extinctions and 50 million years before taking over the world and dominating ecosystems

Sep 30, 2008
A herd of primitive carnivorous dinosaurs (Coelophysis, foreground) is enveloped by a sandstorm, while a large carnivorous crocodile-like archosaur (Postosuchus) and several early sauropodomorph dinosaurs lurk in the background. This reconstructed scene is taken from Steve Brusatte´s new book Dinosaurs which is advised by Mike Benton and will be published in October 2008 by Quercus Publishing, London.

Reporting in Biology Letters, Steve Brusatte, Professor Michael Benton, and colleagues at the University of Bristol show that dinosaurs did not proliferate immediately after they originated, but that their rise was a slow and complicated event, and driven by two mass extinctions.

"The sheer size of dinosaurs like Tyrannosaurus makes us think there was something special about these animals that preordained them for success right from the beginning," Brusatte said. "However, our research shows that the rise of dinosaurs was a prolonged and complicated process. It isn't clear from the data that they would go on to dominate the world until at least 30 million years after they originated."

Importantly, the new research also shows that dinosaurs evolved into all their classic lifestyles – big predators, long-necked herbivores, etc. – long before they became abundant or diversified into the many different species we know today.

Brusatte added: "It just wasn't a case of dinosaurs exploding onto the scene because of a special adaptation. Rather, they had to wait their turn and evolved in fits and starts before finally dominating their world."

Dinosaurs originated about 230 million years ago and survived the Late Triassic mass extinction (228 million years ago), when some 35 per cent of all living families died out. It was their predecessors dying out during this extinction that allowed herbivorous dinosaurs to expand into the niches they left behind.

The rapid expansion of carnivorous and armoured dinosaur groups did not happen until after the much bigger mass extinction some 200 million year ago, at the Triassic-Jurassic boundary. At least half of the species now known to have been living on Earth at that time became extinct, which profoundly affected life on land and in the oceans.

Historically the rise of the dinosaurs has been treated as a classic case in which a group evolves key features that allow it to rapidly expand, fill many niches, and out-compete other groups. But Professor Benton said the story isn't so simplistic: "We argue that the expansion of the dinosaurs took up to 50 million years and was not a simple process that can be explained with broad generalizations."

Source: University of Bristol

Explore further: Aging white lion euthanized at Ohio zoo

add to favorites email to friend print save as pdf

Related Stories

International team maps 'big bang' of bird evolution

Dec 11, 2014

The genomes of modern birds tell a story of how they emerged and evolved after the mass extinction that wiped out dinosaurs and almost everything else 66 million years ago. That story is now coming to light, ...

Recommended for you

A vegetarian carnivorous plant

Dec 19, 2014

Carnivorous plants catch and digest tiny animals in order and derive benefits for their nutrition. Interestingly the trend towards vegetarianism seems to overcome carnivorous plants as well. The aquatic carnivorous bladderwort, ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Adam
not rated yet Oct 01, 2008
The Age of Dinosaurs was preceeded by the Age of Protomammals & Archosaurs - both of which lost many species in the terminal Permian and Triassic extinctions. Was never a sure thing, the rise to dominance, for any animal group - mammal, archosaur or dinosaur - and that should be a lesson to ourselves.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.