SCIENCE

Dinosaur Skeleton Reveals Babies May Have Lived On Their Own From Birth

Giant dinosaurs were small and cute at birth, a study of baby Rapetosaurus bones reveals.

The rare discovery of a fossilized skeleton from a newborn dinosaur suggests that some long-necked plant eaters lived on their own from the moment they hatched from eggs. 

Paleontologists who recently examined the fossils of a weeks-old Rapetosaurus, found in Madagascar, said the partial skeleton may lead to a new understanding of the group of dinosaurs known as sauropods, which included some of the largest creatures to ever walk on land.

The fossils also suggest that a baby Rapetosaurus grew rapidly toward its gigantic adult dimensions. 

"We never knew anything about what they looked like when they were babies. We haven't had any data that can shed light on the question until now," Kristi Curry Rogers, paleontologist at Macalester College in Minnesota, said in a video (above) announcing the research. She added that the skeleton was "the smallest of its kind out of an egg."

The remains were small enough that they were initially misidentified as coming from a fossilized crocodile. They were mixed among other fossils until Rogers recognized their significance. Rogers and her team published their findings in the journal Science on Thursday. 

A comparison of an adult <i>Rapetosaurus</i>, a baby <i>Rapetosaurus</i> and a human.
A comparison of an adult Rapetosaurus, a baby Rapetosaurus and a human.

Living about  67 million years ago, an adult Rapetosaurus -- a type of titanosaur -- could reach a length of 15 meters, or 49 feet. The fossils were from a specimen that "was probably only about 35 centimeters, or knee height," Rogers said. "You could have picked this animal up and carried it just like you could carry a golden retriever."

After analyzing the fossils, the researchers estimated that the baby dinosaur may have grown from being around 7.5 pounds (3.4 kilograms) when it hatched to about 88 pounds (40 kilograms) when it died, National Geographic reported.

"That’s like going from chihuahua to a Great Dane in six weeks," Sarah Werning, a paleontologist at Des Moines University who was not involved in the study, told National Geographic.

The egg that it hatched from was likely the size of a soccer ball, according to the National Science Foundation, which funded the research.

The baby dinosaur not only was small, but also likely adorable.

"There is no doubt that these baby titanosaurs would have had some of the features we would normally associate with cuteness or baby-ness: short snout, large eyes, big head for a body -- like a puppy," Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles, who wasn't involved in the research but praised it, told The Associated Press.

The preserved skeleton of the baby <i>Rapetosaurus</i>, including several vertebrae from the hip and tail.
The preserved skeleton of the baby Rapetosaurus, including several vertebrae from the hip and tail.

From birth, the Rapetosaurus was more coordinated than full-grown adults and survived without parental care, according to the scientists. 

"These little sauropods would hatch from their eggs and they would really be on their own in a really rough environment," said Rogers in the video.

An analysis of the cartilage growth plates of this particular dinosaur suggests it may have died of starvation.

Rogers also published a paper in 2001 about discovering the first fossils of an adult Rapetosaurus in Madagascar in 1996, when she was a graduate student

Earlier this week, other scientists published a report concluding that dinosaurs may have already been dying off tens of millions of years before a devastating asteroid led to their demise. According to that paper, sauropods like the Rapetosaurus were the kinds of dinosaurs dying at the fastest rate.

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