Dinosaurs too had teenage pregnancies

January 15th, 2008 - 12:29 pm ICT by admin  


Washington, Jan 15 (ANI): A new study by researchers at Ohio University and University of California at Berkeley has found that dinosaurs reached sexual maturity long before they were fully grown, becoming pregnant in their early adolescence.

The researchers have discovered medullary bone, the same tissue that allows birds to develop eggshells, in two new dinosaur specimens: the meat-eater Allosaurus, plant-eater Tenontosaurus.

It has also been found in Tyrannosaurus rex.

The findings helped researchers identify the age of these pregnant dinosaurs, which were 8, 10 and 18.

According to the researchers, the discovery suggests that the creatures reached sexual maturity earlier than previously thought.

In order to learn more about dinosaur growth rates, the researchers originally studied the bones, which come from different geologic periods.

Andrew Lee, a postdoctoral student at the Ohio University College of Osteopathic Medicine who conducted the work as a graduate student at University of California at Berkeley with scientist Sarah Werning, said that because researchers rarely find fossils of adult dinosaurs, some have speculated that the ancient beasts never stopped developing.

The finding suggests that dinosaurs were born precocious and suffered high adult mortality, making early sexual maturity necessary for survival.

We were lucky to find these female fossils. Medullary bone is only around for three to four weeks in females who are reproductively mature, so youd have to cut up a lot of dinosaur bones to have a good chance of finding this, Werning said.

According to the researchers, their study also offers more evidence that dinosaurs were less like reptiles and more like birds.

Dinosaurs had offspring before adulthood, but their early sexual maturity was more a function of their tremendous size than any anatomical similarity to crocodiles.

When they factored in the size of the dinosaurs, the researchers found that the reptile model for sexual maturity predicted that they would have had offspring as late as age 218.

The study shows that most dinosaurs had a lifespan of about 30 years, though long-necked creatures such as Brontosaurus might have had a life of 60 years.

We hope this is the last nail in the coffin, but some scientists still cling to the notion that dinosaurs werent like birds, Lee said.

The study is published in the journal Proceedings of the National Academy of Sciences. (ANI)

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