Scientists report evidence of a new but now extinct species of ancient terrestrial sloth

The evidence was first discovered in January 2009, when divers found the bones of a sloth in a flooded cave on the island of Hispaniola (now home to the Dominican Republic and Haiti)
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After extensively studying some bones and bones of several other specimens, the scientists concluded that this is a previously unknown ground sloth, and they named it the Dominican sloth (Parocnus dominicanus)

Scientists say this discovery is important because “it allows us to explain the variation in the fossil record,” said Dr.
Siobáhn Cooke, an assistant professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine
.

"If we try to reconstruct the lives of animals, we need to understand their relationships, anatomy and habitat

The researchers' findings were published on August 31 in "Vertebrate Anatomy, Morphology and Paleontology
.

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Cook pointed out that the two-toed and three-toed sloths found in the forests of Central and South America today are smaller than the sloths 5,000 years ago
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The ancestors of modern sloths migrated north to parts of what is now North America.

"I am biased, but I think sloths are great animals," said Dr.
Robert McAfee, associate professor of anatomy at the Philadelphia College of Osteopathic Medicine
.

"They are an underestimated species with unique adaptability and can live in a variety of habitats," he added

On Hispaniola Island, scientists have previously discovered six or seven species of ancient sloths
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Cook said the newly discovered evidence was found in a cave called Padre Nuestro at the eastern end of the Dominican Republic, which is now flooded but was once dry
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In order to explore this cave, the scientists collaborated with diving experts who are good at navigating in the water-filled cave environment

Scientists don't know whether the sloth fell into the cave or crawled in and couldn't escape
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Compared with the first sloth species found on the island, the Dominican sloth is approximately 10% to 15% smaller in all bone measurements found
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The scientists also discovered that the position where the deltoid muscle attaches to the forelimb is different from the previously identified species brownie and serus

The muscle attachment puts the difference of muscles in different positions, and may provide a larger range of movement, strength and ability to manipulate its forearm, walking in the lower habitat of its forearm, instead of climbing on the tree and hanging upside down.
, The characteristics of modern sloths
.

To consolidate the belief that the Dominican sloth is a new species, they studied the fossil record of ancient and extinct sloths found on Caribbean islands
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They said that new bone specimens have always been relatively small

Sloths disappeared from the Caribbean Sea about 4000 years ago, and humans came to America about 5000-6000 years ago
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Therefore, the researchers say that humans and sloths have coexisted in the area for about 1,000 years
.
They said that it is unclear whether sloths are widely hunted on the island or their disappearance is due to changes in the habitat caused by humans
.

Funding for this investigation and research was provided by the Ernstmeier Travel Fund for Zoological Systematics in the Harvard University Museum of Comparative Zoology 2015
.

In addition to Cooke and McAfee, other research participants included Sophia M.
Beery of Ohio University, Renato Rímoli of the Museum of Humanity of the Dominican Republic, Juan Almonte of the National Museum of Natural History of the Dominican Republic, and Phillip Lehman of the Speleology Society of the Dominican Republic
.

Journal Reference :

1. Robert McAfee, Sophia Beery, Renato Rimoli, Juan Almonte, Phillip Lehman, Siobhan Cooke.
   New species of the ground sloth Parocnus from the late Pleistocene-early Holocene of Hispaniola .
   Vertebrate Anatomy Morphology Palaeontology , 2021; 9 (1) DOI: 10.
   18435/ vamp29369