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A new study presents the life of Cretaceous mammals and dinosaurs 66 million years ago, before the hit of the asteroid that brought their extinction. Scientists revealed that dinosaurs were not the dominating species, as it was initially thought.
On the contrary, the life of therian mammals was very diverse, and their species had a separated evolutionary path that proved to be as complex as the one of the dinosaurs.
The Cretaceous Mammals Teeth Study
Researchers in evolutionary biology started with the study of teeth found in 20 million years old fossils. These animals were all living before the occurrence of the Cretaceous-Tertiary event that killed the dinosaurs.
The analysis revealed animals with a large variety of diets that were part of unique species, evolving separately from the dinosaurs. Scientists were taken by surprise, as the old theory showed mammals as being much inferior to dinosaurs, and having a less interesting evolutionary path.
However, it seems that dinosaurs were not the kings of the disappeared world. Many other species had features and evolutionary developments just as complex.
Who Survived the K-Pg Boundary?
The Cretaceous-Tertiary event that produced the disappearance of dinosaurs left a mark on the deep bed rocks that paleontologists named K-Pg Boundary. The geological signature reveals the end of the Cretaceous Period, and thus separates life before and after the extinction.
The traditional view was that the K-Pg Boundary event was disastrous only for dinosaurs. Birds and other Cretaceous mammals were thought to have successfully survived. However, scientists discovered that many other species of animals were incapable of protecting themselves from the calamities that followed the asteroid crash.
Again, the evidence of who survived came from teeth analysis. The animals that had specialized diets were less likely to cope with the new environmental changes. This included herbivores or mammals that ate only bugs. Those who did survive had a more varied regime that permitted them to eat whatever they could find.
Life after Mass Extinctions
Earth experienced five drastic climate changes in the last half billion years. Scientists are trying to use these findings to prepare for a possible new extinction event that may be driven by the climate changes. They hope to find out who will be more equipped to survive, and what could be done to sustain life and to protect human habitat.
The Cretaceous-Tertiary event destroyed three-quarters of the species living on Earth. No large tetrapods survived, with the exception of crocodiles and sea turtles.
However, the extinction did not stop the evolution of species on Earth. After dinosaurs had disappeared, the living conditions of the new world sustained the apparition of whales, bats, and primates.
Image Source: Wikipedia