Dinosaur was female and pregnant: Fossilized bone tissue reveals
AFTER 68 million years, it’s something of a challenge to even guess the sex of a dinosaur.
But, in the case of one Tyrannosaurus rex fossil recently found in the US state of Montana, we know she was feeling somewhat clucky.
A close look at the broken femur of this particular example revealed a type of tissue — medullary bone — found only in female birds while they are carrying eggs.
“It’s a dirty secret, but we know next to nothing about sex-linked traits in extinct dinosaurs,” study co-author Lindsay Zanno of the North Carolina Museum of Natural Sciences said in a release.
“Just being able to identify a dinosaur definitively as a female opens up a whole new world of possibilities,” she added. “Now that we can show pregnant dinosaurs have a chemical fingerprint, we need a concerted effort to find more.”
Could such fossil contain DNA?
“Yes, it’s possible,” Zanno told Discovery News. “We have some evidence that fragments of DNA may be preserved in dinosaur fossils, but this remains to be tested further.”
SEVERAL BONES TO PICK
The study’s lead author is no stranger to fossil breakthroughs. In 2005 Mary Schweitzer uncovered what she believed to have been soft blood vessels preserved in fossilised bone for millions of years.
While that research remains controversial, the new find opens up a world of possibilities when it comes to understanding dinosaur behaviour.
In this study, a large portion of the T-Rex’s fossil was recovered — including its skull. We know the mum-to-be was about 16 years old. We don’t know why she died.
But having her sex confirmed will allow researchers to seek further gender-specific traits among her bones.
“This analysis allows us to determine the gender of this fossil, and gives us a window into the evolution of egg-laying in modern birds,” she said in a statement.
The theropod family of dinosaurs, of which T-Rex is among the most famous, eventually evolved into the birds we know today.
The medullary tissue is built up as an activate calcium store to harden the shells of their eggs just before laying.
While Schweitzer said all indications are the tissue is medullary bone, chemical analysis needs to be completed to ensure it’s not a disease such as osteopetrosis.
The main giveaway, however, is the presence of keratin sulfate — a substance only present while eggs are forming and carried.
“The discovery of medullary bone is just one more piece of evidence that blurs the line between birds and other theropod dinosaurs like T. rex,” Schweitzer said.
The researchers compared their results with those done on modern ostrich femurs.
However, the overall usefulness of detecting such medullary bone tissue is not certain as it only lingers for a short time after pregnancy. And finding it involves breaking up fossils — and dissolving them.
An artist’s impression of Timurlengia euotica. Picture: Proceedings of the National Academy of SciencesSource:Supplied
T-REX WAS LITHE AND BRIGHT IN ITS EVOLUTIONARY YOUTH
The king of the dinosaurs wasn’t always a lumbering, clumsy clot. Fragments of a new dinosaur found in Uzbekistan suggests tyrannosaurs got smart long before they got big.
The horse-size T-Rex predecessor lived as far back as 170 million years ago, in the Jurassic period. Its regal descendant, among the biggest carnivores to have stalked the Earth, date from 80 million years ago.
But palaeontologists have been struggling to fill in an evolutionary gap to explain how the tyrannosaur got its keen eye, ear and nose.
This new fossil, found in the Kyzylkum desert and dating from 90 million years ago, appears to show a horse-sized predator with a remarkably well developed inner ear.
It’s been named Timurlengia euotica: “well-eared Timurleng”.
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