A hedgehog smaller than a mouse and a dog-sized tapir are the first mammals ever to be discovered at a fossil site in British Columbia, which is renowned for its preserved plants, insects and fish.
Scientists made this discovery by accident, when David Greenwood of Brandon University in Manitoba and his colleagues were quarrying for plant fossils in the lakebed shales of Driftwood Canyon Provincial Park.
A student cracked open a rock and found a tiny bone inside, which turned out to be a partial jaw and some teeth belonging to a previously unknown species of hedgehog, called Silvacola acares, meaning "tiny forest dweller" in Greek and Latin.
The fossils date back to between 50 and 53 million years ago to the Eocene Epoch, one of the warmest periods on Earth since the extinction of the dinosaurs.
According to researchers, Silvacola acares was around two inches long and ate insects, plants and possibly seeds. It lived roughly 13 million years after an asteroid wiped out the dinosaurs, leaving the mammals as the dominant land animals.
An industrial computed tomography scanner was used to capture 3D X-ray images of the creature's tiny teeth, to avoid damaging the delicate jaw.
"We were surprised by its tiny size, and frankly it threw me for a while and made it difficult to identify," researcher Professor Jaelyn Eberle, of the University of Colorado, told Reuters.
"Today's hedgehogs, and especially the ones that are kept as pets, are considerably larger. The smallest living hedgehogs are about four to six inches long, not including the tail," Eberle said.
The mini-hedgehog may or may not have had a prickly back, the scientists added.
''We can't say for sure,'' Prof Eberle told the Telegraph. ''But there are ancestral hedgehogs living in Europe about the same time that had bristly hair covering them, so it is plausible Silvacola did too.''
Researchers also discovered a miniature tapir in coal-rich rock beds in the park, the site of a swampy spot in the Eocene and a rare place to find vertebrate fossils.
Called a heptodon, the animal was half the size of modern tapirs and lacked their distinctive short trunk.
''The discovery in northern British Columbia of an early cousin to tapirs is intriguing because today's tapirs live in the tropics,'' said Prof Eberle, as reported by NBC.
Prof Greenwood, co-author of the research, said: ''Driftwood Canyon is a window in to a lost world, an evolutionary experiment where palms grew beneath spruce trees and the insects included a mixture of Canadian and Australian species."
''The early Eocene is a time in the geological past that helps us understand how present-day Canada came to have the temperate plants and animals it has today. However, it can also help us to understand how the world may change as the global climate continues to warm.''
The researchers reported their findings in the Journal of Vertebrate Paleontology.