How little has changed: Our earliest ancestor had a big mouth

New species pushes our origins as far back as 450 million years ago

The earliest known human ancestor was a microscopic sea creature — and it had one huge mouth.

The freaky- looking thing lived about 450 million years ago and now takes the prize as humanity’s earliest ancestor, according to a study released Monday.

Scientists believe the creature was a common ancestor of many species and the earliest step yet found on the evolutionary path that eventually led to humans hundreds of millions of years later.

It has been named “Saccorhytus” after the sacklike features created by its elliptical body and gigantic mouth. The species is new to science and was identified from micro- fossils found in China.

It is thought to be the most primitive example of a “deuterostome” — a broad biological category that includes several subgroups, including all vertebrates.

“We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves,” study co- author Simon Conway Morris of St John’s College at the University of Cambridge said in a statement.

“To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw- dropping,” Morris said. The actual creature was probably no more than 1 millimeter in size.

The animal probably lived between grains of sand on the seabed. Its features were wellpreserved in the fossil record — and intriguingly, the researchers found that the evidence suggests the creature may have both eaten and excreted through its mouth.

The study, which was led by Jian Han of Northwest University in China, appeared in the peerreviewed British journal Nature.

ARTIST’S RECONSTRUCTION BY JIAN HAN, NORTHWEST UNIVERSITY, CHINA Saccorhytus probably was small enough to live between grains of sand on the seabed, but its yapper was hard to miss.