The largest dinosaurs were almost independent from the moment they were born, a new study suggests.
A team of US scientists analysed the fossilised bones of a Rapetosaurus, which lived 67 million years ago, and found its bones were in the same proportion as adult specimens.
The researchers concluded that, unlike other types of dinosaurs, the animal, which was only a few weeks old, required little parental assistance after hatching.
“They were probably capable of more independent locomotion and able to forage more quickly after they arrived on the scene,” palaeontologist Kristina Curry Rogers, from Macalester College, Minnesota and author of the report in Science, told reporters.
Rogers said that being independent shortly after hatching gave the animal an evolutionary advantage as it gave it a better chance of avoiding predators.
The team took a series of detailed measurements of the baby’s bones and compared the proportions of, for instanct, mid-shaft circumference and bone length to a number of older Rapetosaurus skeletons.
The researchers estimated the young dinosaur specimen weighed between 2.5 and 4.3 kilograms when it was born. When it died between 39 and 77 days later it weighed 40 kilograms and was around 35 centimetres tall.
That is just over 10% the size of a fully grown Rapetosaurus, which were about 15 metres long with a small head, a very long neck, an elephant-like body and a short, slender tail.
“Despite massive changes in body size the proportions stayed the same,” Rogers said.
The Rapetosaurs were part of the group of dinosaurs known as titanosaurs. There have been about 30 new species of titanosaurs found in the last 15 years but this specimen, found in Madagascar, is the smallest to have been discovered.
Bill Condie is a science journalist based in Adelaide, Australia.
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