The discovery of a pregnant Tyrannosaurus rex may bring scientists one step closer to cloning dinosaurs, according to a study published on March 15 in the journal Nature Scientific Reports. The 68 million-year-old remains were found in Montana, which contained a preserved medullary bone that revealed its pregnancy that might have retained the dinosaur’s DNA.

According to Lindsay Zanno, an assistant research professor of biological sciences at North Carolina State University, more tests are still needed to confirm the DNA on the fossils. Apparently, this T. rex was between 16 to 20 years old when it died of unknown causes.

The medullary bone is only found in female living dinosaurs like birds, present just before and during egg laying but disappears after the female has laid eggs. It lines the marrow cavity of a bird’s long bones. Chemical analysis of the femur revealed karatan sulfate, a substance not found in other bones.

Tyrannosaurus rex holotype specimen at the Carnegie Museum of Natural History, Pittsburgh. Photo from Wikipedia/ScottRobertAnselmo

Tyrannosaurus rex holotype specimen at the Carnegie Museum of Natural History, Pittsburgh. Photo from Wikipedia/ScottRobertAnselmo

“It’s a special tissue that is built up as easily mobilized calcium storage just before egg laying,” adds Zanno. “The outcome is that birds do not have to pull calcium from the main part of their bones in order to shell eggs, weakening their bones the way crocodiles do.”

So far, the scientists do not have the technology that could clone a T. Rex and other dinosaurs. Still, the scientists believe that they could still be able to provide information on the dinosaur’s anatomy and appearance, thanks to the preserved skeleton.

Another study from the University of California and Berkeley has also found a medullary bone in an Allosaurus, a carnivorous close relative of T. rex and Tenontosaurus, a duck-billed herbivorous dinosaur. This showed that these dinosaurs could have died just before during or after laying eggs.

“We were lucky to find these female fossils,” said Assistant Professor Sarah Werning of the University of California and Berkeley. “Medullary bone is only around for three to four weeks in females who are reproductively mature, so you’d have to cut up a lot of dinosaur bones to have a good chance of finding this.”