Laurasichersis relicta: Primitive Turtle Species Survived The Dinosaur-Killing Asteroid
When the dinosaur-killing asteroid hit the Earth about 66 million years ago, it wiped out 70 percent of all life on the planet, including many groups of primitive tortoises that were living with the dinosaurs. In fact, nearly all of the primitive turtle groups were wiped out.
However, a paleontologist discovered the only primitive turtle species that managed to survive the wipe-out in the northern hemisphere.
Today, all the turtle species we are aware of descended from two lineages that separated during the Jurassic era, about 160 million years ago. Apart from the two turtle lineages that persist until today, there were also many primitive turtle species in an earlier evolutionary position that lived with the dinosaurs as well. However, virtually all of the were wiped out by the asteroid impact.
Based on fossil records in South America and Oceania, horned turtles were the only primitive turtles that survived the asteroid impact in Gondwana, now known as the southern hemisphere. Unfortunately, their descendants were eventually hunted by humans into extinction. Apart from the horned turtles, no other primitive turtle species from the last 66 million years have been recorded.
That is, until recently, when paleontologist Adán Pérez García of the National University of Distance Education in Spain confirmed another primitive turtle species, the Laurasichersis relicta, that survived the mass extinction in the ancient continent Laurasia, now known as the northern hemisphere.
This now-extinct species had separated from Gondwana tortoises a hundred million years prior and, for reasons that still remain unknown, they survived the mass extinction when none of the other primitive turtles did.
The turtle is just about 60 centimeters long in adulthood and was not capable of retracting its head inside its shell, just like other primitive reptiles. Because of this disadvantage, it had defense mechanisms such as spikes on its legs, neck and tail.
Somehow, this species ended up surviving the asteroid impact and continued to live with the new predators in the new environment.
“The fauna of European turtles underwent a radical change: most of the forms that inhabited this continent before the extinction disappeared, and their role in many ecosystems was left vacant until the relatively rapid arrival of new groups from various places in North America, Africa and Asia,” Pérez García explained.
These surviving turtles all belong to the two turtle lineages that persist until today. With the discovery of the Laurasichersis, we now know that another primitive species survived the mass extinction event in Laurasia.
The study is published in Scientific Reports.