ORINDA, Calif. (KCBS) Building a fourth bore at the Caldecott Tunnel is turning out to be a huge success for an unlikely group: local paleontologists.

Fossils dating back to the Miocene period, some 10 to 15 million years ago, have already been discovered and crews haven’t even started the real digging yet.

“We anticipated maybe a thousand specimens by the time the tunneling was done after two years,” said Dr. Larry Fisk, head paleontologist with PaleoResources Consultant. “But we already have 500 specimens from a hundred sites during preparation to start the tunnel.”

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PaleoResources Consultants was hired by Caltrans to sift through the dirt and Fisk said they’ve found teeth and bones belonging to ancient horses and camels that roamed the area long ago.

“I think the rock type is ideal for preserving fossils. It’s very fine grain and has lots of clays,” said Fisk. “And it hasn’t been oxygenated or brought to the surface and weathered.”

Until now said project spokesman Jeff Weiss with Caltrans.

“Most projects we do are above land,” Weiss said. “And here’s a project where we’re actually boring into the earth so this is rich territory for a paleontologist.”

Fisk said they were pretty sure they would hit pay dirt because construction crews found other fossils when the first, second and third bores were being dug, dating back to the 30s.

“There are a few little scraps of things Cretaceous, which is older than 65 million years. It’s a unit that could contain things that we used to call dinosaurs,” he said,

Fisk said this is a once in a lifetime opportunity and one they get to take part in for the next several years.