Titanosaurs may have been the largest dinosaurs ever to walk the Earth, but new evidence shows that they started small and were basically forced to fend for themselves almost immediately after hatching, according to a new study published Friday in the journal Science.
Kristina Curry Rogers, a paleontologist at Macalester College in Minnesota, and her colleagues found fossils from a baby Rapetosaurus in an ancient 70- to 66-million-year-old rock formation in Madagascar. The specimen, which died (probably of starvation) 39 to 77 days after birth, was found to already have adult-sized proportions and was 14 inches (35 cm) tall at the hip.
Their research suggests that the newborn Rapetosaurus likely would have had a far greater range of movement than an adult member of the species, and the findings support a hypothesis that this type of gigantic dinosaur would have been able to move independently at a very early age, unlike contemporary dinosaurs such as theropods and ornithischians, which required parental care.
“Until now, we haven’t been able to access the earliest record of life for any sauropod dinosaur. This few-week-old baby skeleton tells us a great deal about the growth and early life of newborn sauropods like Rapetosaurus,” Curry Rogers explained in a statement Thursday.
Findings helped in development of a new guidebook
Curry Rogers, who originally named the long-necked, armored, herbivorous Rapetosaurus back in 2001, told National Geographic that she and her fellow researchers found the baby titanosaur fossil while sifting through turtle and crocodile bones from the Madagascar rock formation. This fortuitous discovery presented them with a rare opportunity to study early dinosaur life.
“Our record of the earliest lives of sauropods up to this point has been limited” to a handful of embryos still in the egg and a few juvenile specimens, limiting their ability to learn more about how titanosaurs lived during this part of their lives, she told the publication. Thus, she said that her team “wanted to glean everything we could from these bones, from anatomy and body size estimates to details of bones under the microscope and with micro-CT scanning.”
Through this analysis, they were able to learn that the baby Rapetosaurus likely weighed little more than 7.5 pounds (3.4 kg) at birth, but less than three months later, had grown to nearly 88 pounds (40 kg) when it died. Furthermore, the similarity of its bones to those in adults, and the apparent signs of bone remodeling under stress, indicates that the infant dinosaur was essentially on its own, moving around independently and without parental care shortly after hatching.
The bones, which included a thigh bone, a shin and arm bone, also revealed that the dinosaur was most likely born in a drought-stricken region, which the authors believe may have contributed to its eventual demise. Curry Rogers and her colleagues have used their research to develop a guide for other scientists to help determine if a specific dinosaur species was independent at birth, or if it spend an extended amount of time being cared for by its parents.
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Image credit: Wikimedia Commons
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