Paleontology: the mystery of the 500 million year old creature without an anus is solved

August 19, 2022

Victoria Gill BBC Science Correspondent


image caption,

Artistic reconstruction of Saccorhytus coronarius, based on the original fossil finds.

Scientists claim to have solved an evolutionary mystery involving a 500 million year old microscopic spiny creature with a mouth but no anus.

When discovered in 2017, it was claimed that this tiny fossil of a bag-like sea animal may be the earliest known ancestor of humans.

Saccorhyntys coronarius, as this ancestral creature is called, has been tentatively classified in the group of deuterostomes, which are characterized by the formation of their anus before the mouth during embryonic development.