Before the first dinosaurs emerged, the ancestors of mammals were the top predators on Earth. Experts suggest that these first large terrestrial carnivores evolved new tools in order to develop their skills as hunters.
Predator-Prey Relationships
During the late Paleozoic era, animals began living, eating, and reproducing entirely on land. As these creatures became fully terrestrial, they could colonize new habitats and exploit new resources further inland from the aquatic environments they had previously relied on.
For almost 60 million years, ancestors of mammals ruled the Earth, long before the existence of the first dinosaurs. Between 315 and 251 million years ago, these creatures diversified as the top predators on land.
Before the 'Age of Dinosaurs' began, the interaction between predator and prey heated up on land. As herbivores grew larger, ancient carnivores needed to find ways to give themselves an advantage.
Later, predators evolved their ability to deliver powerful blows to their prey. This caused massive injuries and blood loss. As a result, more extensive and faster herbivores needed to develop new ways of hunting.
Since the risk of getting injured or killed went up, carnivores became bigger and better killers to overcome these challenges.
Predator-prey interactions have influenced the anatomical evolution of animals over millions of years. They are potentially responsible for driving great breakthroughs in mammals' evolutionary history, possibly even having an important part in animal behavior today.
Evolution of Killer Instinct
At the University of Bristol, paleontologists attempted to track the evolutionary changes in predatory behavior of ancient mammalian ancestors. They focused on examining the jaw anatomy and body size of carnivorous synapsids. The result of their study is discussed in the paper "Predatory synapsid ecomorphology signals growing dynamism of late Palaeozoic terrestrial ecosystems."
Synapsids refer to a group of animals considered ancestors of modern-day humans. Ancient synapsids are known as mammal-like reptiles and dominated during the Permian period, about 299 to 252 million years ago. Sometimes referred to as "stem mammals" or "proto mammals," these organisms are not reptiles but the evolutionary ancestors of mammals.
Led by Dr. Suresh Singh from Bristol's School of Earth Sciences, a team of scientists used the jaw anatomy and body size of carnivorous synapsids to reconstruct their potential feeding habits. These traits were also used in charting the ecological evolution of these ancient predators.
Singh and his colleagues discovered a major shift in synapsid jaw function about 270 million years ago. This was linked to a crucial change in predatory behavior, which had important implications for the evolution of our earliest ancestors.
Earlier synapsid predators had fairly long jaws with many teeth, which they used to ensure their prey would not escape after ensnared them. However, the researchers observed a shift in function towards shorter jaws with greater muscle efficiency. They also saw fewer teeth concentrated at the front of the jaw, adapted to deliver deep, powerful bites.
According to the researchers, the change indicates that later synapsid carnivores emphasized heavily injuring and quickly killing their prey. Such change shows that predators faced new selective pressures from their prey.
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