First fossilized pregnant turtle found in Alberta
The Canadian Press
Published Friday, August 29, 2008 9:22AM EDT
CALGARY - Nine years after its discovery in the badlands of southeastern Alberta, the 75-million-year-old fossil of a pregnant turtle finally made its public debut Wednesday.
At 40 centimetres long, its turtle shape is still evident and most of its skeleton is complete but its shell is crushed. The pregnant fossil was found in 1999. Six years later, a fossilized nest of eggs was found from the same species about 50 kilometres away.
Both specimens belong to an extinct turtle called Adocus, a large river turtle that lived with the dinosaurs and resembles today's slider and cooter turtles.
"It is the first fossil of a pregnant turtle found in the world and it's only the second fossil of an animal found in the world that's pregnant," explained Darla Zelenitsky, a University of Calgary scientist whose expertise is fossil nest sites.
Both were found south of Medicine Hat in the Manyberries area by scientists and staff from the University of Calgary and the Royal Tyrrell Museum of Paleontology
"It's a very primitive turtle and it's basically an ancestor of modern turtles so we can look at characteristics of the eggs and nests and we can learn about the evolution of these traits in turtles today," she added.
So why are these discoveries only being revealed now?
"The turtle was prepared at the Royal Tyrrell Museum so basically the fossil was removed from the rock so that probably took about a year," said Zelenitsky. "Last year we finally finished the preparation of the turtle nest so I wanted to publish them together in a single paper so that's why it's out now."
Zelenitsky's discovery was published Wednesday in the British journal Biology Letters.
"Although it is relatively rare to find the eggs and babies of extinct animals, it is even rarer to find them inside the body of the mother," said Zelenitsky, who was also involved in the first discovery of a dinosaur with eggs inside its body.
It was almost by accident that scientists realized that the fossil turtle was pregnant.
"The turtle specimen was partly broken when it was first discovered. It is this fortuitous break that revealed that the fossil was a mother," says Francois Therrien, a co-investigator of the study and curator of dinosaur paleoecology at the Royal Tyrrell Museum.
"The odds of actually of finding an animal that died and was fossilized at the time it was basically laying its eggs is basically one in a million so when you find something like that you know you've found something that is unique," he said.
The remains of at least five crushed eggs were visible within the body of the fossil female and a CT scan exposed more eggs hidden under its shell.
The turtle could have produced around 20 eggs. The nest, which was laid by a different female, contained 26 eggs, each approximately four centimetres in diameter.
It's likely there are more are out there, say scientists.
"Absolutely, that's why we keep going back every summer in the hope that you actually find something new that was not known before," said Therrien.
"Those finds come once in a lifetime maybe, so you want to be there to find them when they come out of the rocks."