Some early carnivores were built to walk on ground, not sit on trees

Washington, December 23 (ANI): A new research that has reworked the carnivore family tree has determined that some early carnivores were built to walk on the ground at least part of the time, and were not all sitting in the trees.

Carnivores, currently a diverse group of mostly meat-eating mammals like bears, cats, raccoons, seals, and hyenas, had been considered arboreal in their early evolutionary history.

Now, more than a hundred years after its discovery, the limbs and vertebrae of a fossil have been pulled off the shelf at the American Museum of Natural History to revise the view of early carnivore lifestyles.

The study into the skeleton of 'Miacis' uintensis has made it clear that some early carnivores were built to walk on the ground at least part of the time.

"Carnivores are highly varied today, and they were also very diverse in the past," said lead author Michelle Spaulding, a doctoral candidate at Columbia University and the Museum.

"Examination of this fossil tells us that they were not all sitting in trees, looking down. 'M.' uintensis did not have a lot of adaptations for an arboreal lifestyle," she added.

'M.' uintensis was discovered on an American Museum of Natural History expedition in 1894 among the brown and red sandstones of the White River beds in Utah.

The specimen dates to 39-42 million years ago.

But the species is more than teeth and a jaw.

Another specimen found in 1896 is more complete, represented by much of the skull, shoulder bones, limb bones, and even some tiny foot and finger bones.

This specimen remained on a shelf in the Museum, largely ignored, because its teeth were badly crushed.

"When I examined the femur, I immediately knew this was a terrestrial animal because of the shape of its knee. It has a long and deep groove where the patella, or kneecap, would go," said Spaulding.

If the early carnivore had been exclusively arboreal, the end of the femur would have had a flatter surface so that the joint would have a greater range of motion.

Spaulding and John Flynn, Frick Curator of Fossil Mammals at the Museum, found other indicators of terrestrial locomotion on bones like the radius, one of the two lower arm bones.

The distal part of the radius, or the portion of the bone that would be in contact with the wrist, of 'M.' uintensis has an oval shape with a projection above the rim.

These features also reduce the range of motion, making limbs more stable for walking on the ground. (ANI)