Recently a study revealed why mammals are so successful: starting out small and uncomplicated! Mammals’ ancestors, from 300 million years ago, had skulls and lower jaws that were made of different bones. This was something shared with other animals with backbones like fish and reptiles.
Many millions of years ago, early mammals had a lot more skull bones than creatures we see today. Recently, scientists figured out the reason for this change by using computers and stress tests. They published their results in the journal Communications Biology.
Researchers discovered that reducing the number of skull bones did not make them stronger, or able to bite harder, like believed before. Instead, they found that the shape of their skulls was designed in a way that allowed them to chew more effectively.
Dr. Stephan Lautenschlager from the University of Birmingham found that early mammals had fewer bones in their skull compared to other types of animals. This allowed stress to be distributed away from the brain during feeding which caused an increase in size for the brains of those mammals!
Changes in the shape of mammals’ skulls, plus them getting smaller, was connected to them eating more insects instead. This led to many different types of mammal being created, which makes up all the different creatures we see today.
Early mammals were a lot smaller than before, with some of them only having 10-12 mm length on their skulls. This meant they needed to adapt to find new sources of food, like insects. Being so small allowed these little animals to survive in the shadows of the dinosaurs living at the same time.
Around 66 million years ago, when the dinosaurs went extinct, mammals finally had a chance to grow and evolve into all the different sizes that we see today.
