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 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." |
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