If you have ever wondered what the sunny West Coast may have looked like during the Ice Age, you may be in luck. An amazing new find by developers in San Diego County has revealed a treasure chest of knowledge in the form of ancient fossils.

Construction workers in Carlsbad, California were stunned to discover fossils that were estimated to be 200,000 years old at a site where 600 houses are slated to be raised. According to a report from UPI, the fossils were unearthed in July, and construction at the site was placed on hold while paleontologists excavate the area.

Researchers uncovered ancient fossils of wooly mammoths, horses, turtles, and even a prehistoric bison. The bison fossil was the second ever discovered in San Diego County.

The fossils were dated back to the Pleistocene Epoch, the last time when the planet was covered in ice. Tom Deméré, the curator of paleontology at the San Diego Natural History Museum, said that the age of the fossils ranges from 50,000 to 200,000 years old.

The fossils could potentially provide information about the climate, environment, and food webs of the time, allowing historical geologists to paint a more accurate picture of life on Earth during the Ice Age. There is no shortage of fossils either – they were uncovered as developers began grading the Quarry Creek site, which spans 60 acres across San Diego County. There are a projected 636 units to be built, and construction is slated to continue at the end of this year.

Researchers will continue to sort through the fossils uncovered at the site, which look nothing like the wildlife in the region today.