New Fossil Carnivore May Explain Why Our Primate Relatives Stayed in Trees

Before the rise of modern carnivores, a meat-lover existed that waited in ambush near trees where our primate ancestors likely lived.

A new and very toothy fossil carnivore has just been discovered in Egypt, and corresponding research could help to explain why our early primate relatives tried to spend as much time as possible in trees.

The meat lover has been named Masrasector nananubis, after the canine-headed Egyptian god Anubis, who was associated with the afterlife. Unearthed at a site called “Locality 41” in Egypt’s Fayum Depression, located west of the Nile and south of Cairo, the new fossil is described in the journal PLOS ONE.

“We found that M. nananubis had limbs most like a fast-moving, ground based carnivore, similar to a fox or mongoose,” lead author Matthew Borths, who co-authored the paper with Erik Seiffert, told Seeker. “It likely hunted by stalking its prey on the ground, or by waiting in ambush in the dense foliage of the forested Fayum for small prey to scamper by.”

The researchers determined that the Anubis namesake lived 34 million years ago and was a hyaenodont. Borths, a researcher at Ohio University’s department of biomedical sciences, and Seiffert, a professor in the department of integrative anatomical sciences at the University of Southern California, explained that hyaenodonts were the top predators in Africa after the extinction of the dinosaurs.

“Despite their name, hyaenodonts are not closely related to hyenas,” Borths continued. “The name means they had hyena-like teeth, which is true. Like hyenas, hyaenodonts were meat eaters and some were bone crackers.”

What’s more, they found that M. nananubis belongs to a lineage of hyaenodonts called the teratodontines, which means “monstrous teeth.” Based on other fossils discovered at Locality 41, this carnivore lived alongside even larger hyaenodonts, such as the coyote-sized Brychotherium and the wolf-sized Akhnatenavus. Large snakes and crocodiles also existed at the site.

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“The environment they all lived in 34 million years ago was a marshy forest, reminiscent of parts of the Everglades or the Louisiana gulf coast, which makes sense because geologists hypothesize the coast was close to the site where these fossils were preserved,” Borths said.

He added that some localities at the site “include fossils of large fruits and trees, evidence this forested habitat would have also been appealing to our early primate relatives.”

It's little wonder that our early relatives tried to spend as much time as possible in trees, given the tasty food above ground and the hungry, blood-thirsty carnivores on the ground. The researchers said that some hyaenodonts did evolve to become tree-dwellling, which could have made life all the more interesting for our primate ancestors.

The impressive teeth of M. nananubis — which featured both meat-slicing, blade-like teeth and teeth designed for grinding — suggest that this carnivore could forage on fruits and seeds, in addition to consuming meaty flesh.

Hyaenodonts over time spread out of Africa and into Europe, Asia and North America. They were once a very successful and widespread bunch, and yet, as far as researchers know, they all died out and left no descendants. Their extinction remains a mystery.

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Borths and Seiffert suspect that tectonic and climatic changes that shook up the planet about 23 million years ago could explain the demise of hyaenodonts, which were rather small-brained. Changing currents at the time started to dry out many parts of the world, with grasslands starting to expand while forests contracted. The ancestors of today’s modern carnivores began to expand into territories that hyaenodonts once occupied.

“The modern African ecosystem with lions and zebras and open grasslands — what I call ‘The Lion King’ ecosystem — is actually a pretty recent phenomenon,” Borths said. “We are interested in the origins of African ecosystems, when we were dealing with ‘The Hyaenodont King.’”

M. nananubis could be at the center of such investigations, since we now know more about it than nearly any other African carnivore from the time between the extinction of dinosaurs and the arrival of modern carnivores, such as cat and dog relatives in Africa. Digital 3D models of the newly found meat eater will allow other scientists in future to make their own conclusions about its lifestyle and evolution.

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