May 14, 2020

Giant Sloths Perfectly Preserved in Tar

Matthew Mann

group of giant sloths was found preserved after “mass death” in a shallow marsh during the last Ice Age.

Sometime during the late-Pleistocene epoch, a group of at least 22 giant sloths (Eremotherium laurillardi), believed to be generations of the same family lineage, died and were preserved in Tanque Loma, Ecuador. Extinct as of nearly 11,000 years ago, giant sloths were a common species in the Cenozoic era. However, very little is known about a creature that is relatively young in its time of being extinct.

In the recently published Paleogeography, Paleoclimatology, Paleoecology, they refer to phenomena such as this as an “asphaltic site“. More commonly known as “tar pits”, these areas where organics decompose, are filled with a tar-like substance that prohibits animals and organics alike from exiting and eventually encases and suffocates the animal, perfectly preserving it in the fossilized liquid. The most famous instance of this is the La Brea Tar Pits in Los Angeles. Said tar pit has provided fossilized evidence of past animals roaming the Los Angeles area for the last 50,000 years. The La Brea Tar Pits Museum has excavated millions of animal remnants which range from present-day canines and bears to mammoths and mastodons.

A depiction of a Mammoth drowning in the tar pit at the La Brea tar Pit Museum.

The process of the organic material of the animal being encased and preserved is the best way the animal can be identified and examined by scientists. In 2011, a northern Alberta oil sands worker discovered a perfectly preserved ankylosaur while operating a shovel. The specimen was believed to have died in a similar matter of the newer animals found in L.A. but is much older. After carbon dating, the ankylosaur was estimated as being 110 million years old and is now the oldest, and best-preserved animal found in the Canadian province.

The preserved Ankylosaur photographed by the Royal Tyrell Museum.

Dr. Emily Lindsey of the La Brea Tar Pit Museum believes that tar pits are the best possible way to look into our planet’s past.


Upon carbon dating the remains from the Eremotherium laurillardi, they found that the bones range from about 18,000 to 23,000 years old. Further analysis of the surrounding sediment and geo-chemicals resulted in proving the area lacked oxygen but had frequent periods of moisture and draught. It was concluded that the grave was likely an aquatic environment, primarily a marsh or swamp. The evidence suggests that the area could have been a frequent watering hole for the animals. It was concluded in the article that the mass death could have resulted from drought and/or disease originating at the water source. They compare this same instance to how large populations of hippopotamus use ponded water sources in the African savannah.

Tar pits are continuing to help scientists understand the relationships that the animals had with their surrounding ecosystems and climate alike. Watching the present-day unfold, maybe looking into our past will help us change the future for better.

No items found.
No items found.