Humans and dinosaurs coexisted cartoonish flintstone, some of our very early ancestors may have shared a brief moment with the likes of Titanosaurus and the iconic Triceratops. According to one report, these distant relatives survived a catastrophic extinction event caused by an asteroid that hit Earth and wiped out non-avian dinosaurs. The study was published in the journal on June 27 biology today.
[Related: The fiery end of the dinosaurs kicked off the golden age of mammals.]
The study reveals that placental mammals, a diverse group that includes humans, dogs and bats, originated during the Cretaceous period and briefly coexisted with dinosaurs before they went extinct. placental mammals All offspring are nourished through an organ called the placenta in the womb.
On a spring day 66 million years ago, an asteroid collided with Earth near Mexico’s Yucatan Peninsula. The ensuing devastation wiped out non-bird dinosaurs and many mammals. names of animals that look like rodents Vintana Sertici It weighed up to 20 pounds and lived in Madagascar. Scientists have long debated whether placental mammals existed before the birth of dinosaurs. Cretaceous to Paleogene (K-Pg) mass extinctionor if dinosaurs only evolved after they went extinct.
According to the team Fossilized remains of placental mammals It is found only in rocks younger than 66 million years. However, molecular data suggest an ancient origin for placental mammals.
In this new research, a team of paleontologists used statistical analysis of the fossil record to determine whether placental mammals originated before this mass extinction event. They collected fossil data from a group of placental mammals dating back 66 million years.
“We have collected thousands of placental mammal fossils and were able to confirm the origins and extinction patterns of different groups. ,” said study co-author Emily Carlyle, a paleontologist at the University of Bristol. said in a statement.
According to the authors, their model infers chronological origins based on when these mammalian lineages first appeared, and infers extinction dates based on when the group went extinct.
[Related: Mammals’ ears may hold the secret to warm-bloodedness.]
They show that groups including primates, rabbits and hares (Lagomorpha), and dogs and cats (Carnivora) evolved just before the K-Pg mass extinction. This means that their ancestors were mixed with dinosaurs. It wasn’t until after the asteroid impact that the modern lineage of today’s placental mammals actually began to take shape. It is likely that, like other mammals, they began to diversify after the dinosaurs disappeared from the shadows.
These early mammals certainly thrived. A group of cat-sized mammals called condylars, which includes the ancestors of today’s ungulates, lived within about the first 328,000 years after the dinosaurs went extinct. Mammals also began to grow significantly as there was less competition for resources. The biggest winner among these mammals was Bronteles, or “Thunder Beast,” who grew from a 40-pound animal about the size of a coyote to a 2,000-pound Goliath.