Students find fossil in Santa Cruz Mountains

Kindergartners and first-graders from Tara Redwood School in Soquel made an astonishing discovery last spring while playing in the Santa Cruz Mountains: a fossil sloth bone that’s the first of its kind in Santa Cruz County.

The elementary school students brought their finding to the Santa Cruz Museum of Natural History, where paleontology advisor Wayne Thompson recognized it as an arm bone that likely belonged to an ancient sloth.

“He knew it was special right off the bat,” said Felicia Van Stolk, executive director for the Santa Cruz Museum of Natural History.

Fossil experts confirmed that the bone came from Megalonyx jeffersonii, a giant plant-eating mammal that roamed North America and lived between 11,500 years and 300,000 years ago. The animal, also known as Jefferson’s ground sloth, is named for thenvice-president Thomas Jefferson, who introduced Megalonyx at a scientific meeting in 1797.

“If there were to be a national

Santa Cruz Museum of Natural History fossil, that would be a good choice,” said sloth expert Melissa Macias, a paleontologist with Applied Earthworks.

The discovery was somewhat rare. Megalonyx only accounts for 14% or 15% of ground sloths that have been found in California, Macias said. Another type of sloth known as Paramylodon makes up 75% or 80%

The ancient sloths were about the size of an ox, growing up to 10 feet long and weighing more than 2,000 pounds. They had one of the largest geographic ranges of the North American sloths, from Mexico up to Alaska, Macias said.

“Megalonyx jeffersonii is one of the very first fossils documented in North America,” Macias said in a statement. “It’s just one of those iconic animals that more people should know about.”

Other types of ground sloths roaming North America during this time were even bigger — as big as an elephant and 18 feet long, Thompson added.

The Santa Cruz Museum of Natural History is working with scientists to further pinpoint the age of the fossil, which will be part of an exhibit starting this weekend and running through May 26.

The specimen not only provides greater insight into Megalonyx, but provides new information about the local area, where it will remain on display.

“It just paints a more rich picture of what the Santa Cruz Mountains looked like in the ice age,” Van Stolk said.

Tara Redwood School

Students from Tara Redwood School uncovered a fossilized sloth bone in the Santa Cruz Mountains.

The fossil that was discovered belonged to the left arm of an ancient sloth.