Fossils from the last Ice Age were found during grading at a construction site in Quarry Creek, Carlsbad, Calif. where new houses will be established. The fossils included bones of a prehistoric Columbian mammoth, bison, turtles and horses, Los Angeles Times reports.

Tom Dumere, curator of paleontology at the San Diego Natural History Museum, said the fossils were all from the Pleistocene Epoch and were as old as 50,000 to 200,000 years. The fossils were discovered in July, and more are expected to be unearthed at the site, according to Fox 5.

"The fossils have the potential to tell us a great deal about the climate, the environment, the ecology of that time when they were living," Dumere told Los Angeles Times. "They are direct connections with the past, an ancient ecosystem that was once common here. We can understand how climates can change by studying these ancient ecosystems."

In California, paleontologists are required at major construction sites such as the one in Quarry Creek. When the fossils were found, construction was stopped and the paleontologists came in to examine and extract them properly.

Cornerstone Communities chief executive Ure Kretowicz said he has worked closely with paleontologists during grading. Cornerstone Communities is the company developing the area.

"They do a [plaster] cast in place, and then remove it," Kretowicz said, according to Los Angeles Times. "We stop everything or go grade another area on the site. Once they're gone, we start up again."

The bison fossil is probably the most complete one found at the site - having parts of a skeleton and a skull - and is bigger than common bisons. The Columbian mammoth found was bigger than the more popular woolly mammoth; it measured up to 13 feet high at the shoulders and weighed up to 10 tons, according to NBC.

Grading will continue at the site for about two more months, and construction of two-storey housing units will begin on 2016.