Long-neck-dinosaur

Dinosaurs 'already in decline' before asteroid apocalypse

Dinosaurs were already in an evolutionary decline tens of millions of years before the meteorite impact that finally finished them off, new research has found.

The findings provide a revolution in the understanding of dinosaur evolution. Palaeontologists previously thought that dinosaurs were flourishing right up until they were wiped out by a massive meteorite impact 66 million years ago. By using a sophisticated statistical analysis in conjunction with information from the fossil record, researchers at the Universities of Reading, UK and Bristol, UK showed that dinosaur species were going extinct at a faster pace than new ones were emerging from 50 million years before the meteorite hit.

he analyses demonstrate that while the decline in species numbers over time was effectively ubiquitous among all dinosaur groups, their patterns of species loss were different. For instance, the long-necked giant sauropod dinosaurs were in the fastest decline, whereas theropods, the group of dinosaurs that include the iconic Tyrannosaurus rex, were in a more gradual decline.

Dr Manabu Sakamoto, University of Reading, the palaeontologist who led the research, said: “We were not expecting this result. While the asteroid impact is still the prime candidate for the dinosaurs’ final disappearance, it is clear that they were already past their prime in an evolutionary sense.”

‘Losing their edge’

“Our work is ground-breaking in that, once again, it will change our understanding of the fate of these mighty creatures. While a sudden apocalypse may have been the final nail in the coffin, something else had already been preventing dinosaurs from evolving new species as fast as old species were dying out.

"This suggests that for tens of millions of years before their ultimate demise, dinosaurs were beginning to lose their edge as the dominant species on Earth.”

Professor Mike Benton of the University of Bristol, one of the co-authors of the research, said: “All the evidence shows that the dinosaurs, which had already been around, dominating terrestrial ecosystems for 150 million years, somehow lost the ability to speciate fast enough. This was likely to have contributed to their inability to recover from the environmental crisis caused by the impact.”

It is thought that a giant asteroid’s impact with Earth 66 million years ago threw up millions of tonnes of dust, blacking out the sun, causing short-term global cooling and widespread loss of vegetation. This ecological disaster meant that large animals reliant on the abundance of plants died out, along with the predators that fed on them.

The new research suggests that other factors, such as the break-up of continental land masses, sustained volcanic activity and other ecological factors, may possibly have influenced the gradual decline of dinosaurs.

'Room for mammals’

This observed decline in dinosaurs would have had implications for other groups of species. Dr Chris Venditti, an evolutionary biologist from the University of Reading and co-author of paper said: “The decline of the dinosaurs would have left plenty of room for mammals, the group of species which humans are a member of, to flourish before the impact, priming them to replace dinosaurs as the dominant animals on earth.”

Dr Sakamoto points out that the study might provide insight into future biodiversity loss. He said: “Our study strongly indicates that if a group of animals is experiencing a fast pace of extinction more so than they can replace, then they are prone to annihilation once a major catastrophe occurs. This has huge implications for our current and future biodiversity, given the unprecedented speed at which species are going extinct owing to the ongoing human-caused climate change.”

World's largest dinos were born self-reliant

Washington D.C, Apr 30 (ANI): If remains of baby Titanosaur is anything to go by, they probably were almost independent from the moment they were born.
Long-necked sauropod dinosaurs include the largest animals ever to walk on land, but they hatched from eggs no bigger than a soccer ball.
Research funded by the National Science Foundation (NSF) and led by Kristi Curry Rogers of Macalester College in St. Paul, Minnesota, sheds the first light on the life of a young Rapetosaurus, a titanosaurian sauropod buried in the Upper Cretaceous Maevarano Formation of Madagascar.
The baby behemoths were active, capable of a wider array of maneuvers than adult members of their species, and didn’t need parental care after hatching.
“These scientists employed several lines of evidence to investigate growth strategies in the smallest known post-hatching sauropod dinosaur,” said researcher Judy Skog.
Skog said the researchers developed tests that could be applied to other perinatal dinosaurs.
The preserved partial skeleton was so small that its bones were originally mistaken for those of a fossil crocodile, said Curry Rogers.
“This baby’s limbs at birth were built for its later adult mass; as an infant, however, it weighed just a fraction of its future size,” Curry Rogers said. “This is our first opportunity to explore the life of a sauropod just after hatching, at the earliest stage of its life.”
“We looked at the preserved patterns of blood supply, growth cartilages at the ends of limb bones, and at bone remodeling,” Curry Rogers said. “These features indicate that Rapetosaurus grew as rapidly as a newborn mammal and was only a few weeks old when it died.”
The tiny titanosaur was mobile at hatching and less reliant on parental care than other animals. Baby sauropods like Rapetosaurus were somewhat like miniature adults, Curry Rogers said.
When taken in the context of the intensely drought-stressed ecosystem represented in the Maevarano Formation, it’s clear that this Rapetosaurus had it rough, Curry Rogers said.
The findings are published in the journal Science. (ANI)