The sloth’s ancestor ate meat, unlike its herbivorous relatives

(CNN) – Modern sloths climb trees, move at a slow pace, and eat a vegetarian diet, but the same cannot be said for their extinct relative, the milodon.
This ancient ground sloth, which lived in South America until about 10,000 years ago, fed on both meat and plants, making it omnivorous. The find, based on new research, contradicts previous scientific knowledge about these gigantic extinct creatures.

“It cannot be determined from our research whether they were sporadic scavengers or opportunistic consumers of animal protein, but we now have strong evidence that contradicts what had traditionally been assumed that all sloths were necessarily herbivores,” said the lead author of the Julia Tejada, a research associate at the American Museum of Natural History and a postdoctoral researcher at the University of Montpellier, France, study in a statement.

Currently there are only six species of sloth, and all of them live in the trees of the rainforests of Central and South America.

But the ancient land sloths were another story. Some of them reached the size of elephants and lived in a wide range of habitats, from Alaska to the tip of South America.

The sloth in the study, known as Darwin’s ground sloth, or Mylodon darwini, probably reached 3 meters in length and weighed between 1,007 and 1,996 kilograms. Analysis of the jaws and teeth preserved as fossils of ancient sloths, as well as fossilized excrement, have always suggested that the milodon and other extinct ground sloths ate plants like their modern counterparts.

However, these clues don’t reveal the whole story of what an animal ate during its lifetime, especially if that animal was rummaging through the garbage.

New evidence from chemical analysis work

The researchers performed a chemical analysis of amino acids, the building blocks of proteins, that were conserved in the hair of the mylodon specimens. When an animal eats certain foods, nitrogen isotopes are trapped in amino acids, which then leave a trace in body tissue, such as hair or nails, and in collagen, which can be found in bones and teeth.

Nitrogen isotope signals can show whether an animal was herbivore, carnivore, or omnivore.

In this case, the analysis revealed that the giant ground sloth ate both meat and plants. The researchers call the sloth an “opportunistic omnivore,” meaning it may have rummaged through the carcasses of other animals or ingested animal protein from eggs.

In addition to studying mylodon’s hair, the researchers analyzed samples from seven species of sloths and their close relatives the anteaters, both living and extinct, for comparison. The team also studied a wide range of modern omnivores.

Another extinct sloth the scientists studied, a ground sloth named Nothrotheriops shastensis that lived in North America, turned out to be a herbivore. But the milodon stood out as a clear omnivore.

Previous research has suggested that there was not enough vegetation to support all the herbivores living in South America at the time, so the mylodon could have turned to other food sources. The new study supports this hypothesis.

“These results, which provide the first direct evidence of omnivory in an ancient sloth species, call for a reassessment of the entire ecological structure of ancient mammalian communities in South America, as sloths represented an important component of these ecosystems in recent years. 34 million years, “Tejada said.

The study was published in October in the journal Scientific Reports.