Ancient sloth and bison fossils were unearthed during excavations for the LA Metro. Giant ground sloths roamed North American around 11,000 years ago, and now new evidence was found during excavations for a transit project managed by the LA County Metropolitan Transportation Authority.
The fossils were discovered on May 16 in a layer of sandy clay 16 feet (5 meters) below Crenshaw Boulevard between 63rd Street and Hyde Park Boulevard, according to a post published May 31 by The Source, a blog about the LA metro.
Ancient sloth and bison fossils were unearthed during excavations for the LA Metro. Image credit: Metro / Curbed Los Angeles
Fossil discoveries in LA have become somewhat usual in recent years
The giant sloth and bison fossils were identified on May 24 by Gary Takeuchi, the collections manager at the La Brea Tar Pits and Museum, who noted the parts were pieces of leg bones, according to a statement by LA Metro representatives.
Fossils or remains of other ancient massive beasts, which roamed North American during the last ice age, have been unexpectedly appearing during other LA construction projects in recent years.
In April, work on a subway line extension near the La Brea Tar Pits had to be temporarily halted due to a fossil discovery in the scene. Paleontologists then announced that a camel bone was recovered, as well as a bone from an elephant relative, a mammoth or mastodon. And back in December 2016, workers of the LA Metro system unearthed a skull and partial tusks, as well as a section of mammoth tusk, also close by the La Brea Tar Pits.
Takeuchi told Live Science that finding these kinds of fossils in LA is not as strange as you might think and that they show up rather frequently.
“Fossils periodically are found during excavation due to construction in the LA area,” said Takeuchi, according to Live Science. “These fossils would probably not have been found if it were not for this construction unearthing them.”
Giant ground sloths roamed North American around 11,000 years ago. Image credit: La Brea Tar Pits / LA Times
Giant ground sloth found in LA Metro could have weighed 1,500 pounds
The fossil corresponding to the bison was identified as a part of a front leg, while the sloth fossil is a femur-head fragment, according to The Source. In photos taken from the fossil fragments next to complete bones from the same animals, the rough pieces found a couple of weeks ago don’t look like much. However, the trained eye of a paleontologist can quickly identify that it’s, in fact, part of the ancient animals, according to Takeuchi.
“The shape and size of the end of long bones can tell you what element in the body and what animal it belongs to,” told Takeuchi to Live Science. “You do not need the complete bone or animal for identification.”
The fossils will be kept at the Paleo Solutions laboratory and will eventually be transferred to the Natural History Museum of Los Angeles County or other accredited museums for permanent curation and possible exhibition.
The Source reported that if the fossil indeed belonged to a Harlan’s Ground Sloth -which was the largest and most common of three species of ground sloth found at the Tar Pits- then the old animal could have weighed up to 1,500 pounds and measured up to 10 feet in length.
Giant ground sloths went extinct around 10,000 years ago
Giant ground sloths evolved in South America around 35 million years ago, and they migrated to North America around 8 million years ago, according to the San Diego Natural History Museum. They were herbivores and preferred forests along lakes or rivers. However, as the Ice Age came along, and glaciers covered around 30 percent of the Earth’s surface, they found it difficult to withstand the climate, and their extinction began.
One species of ground sloth was named after Thomas Jefferson after the president -which had a well-known interest in fossils- identified a sloth fossil that a friend had mistaken for a giant lion fossil. Jefferson was then credited with discovering the extinct sloth, and the species was named Megalonyx jeffersonii, or the giant ground sloth.
Megalonyx fossils have been discovered in over 150 sites across North America, including states like Alaska and Northwest Territories of Canada to Arizona and New Mexico.
It ‘s hard to find out all of the Sloth’s history from just one fragmented bone, but there is some information that can be gathered from the Tar Pits. If the sediments are the same age as the Tar Pits, then the Harlan’s Ground Sloth (Paramylodon Harlani) roamed around the Los Angeles area between 40,000 to 11,000 years ago, in the late Pleistocene era.
Most of the large mammals that lived in the United States, such as sloths, bisons, ancient camels, mammoths, and mastodons, went extinct in North America at least 10,000 years ago during a massive wave of great animal extinction following the last Ice Age.
