Laborious and time-consuming sifting through rocks and other materials followed, when suddenly Smith saw the first of two teeth. Based on the site’s geology, he and his colleagues determined that the teeth were about 145 million years old.
“We already knew the age, but as we progressed through determining what these animals were, my excitement increased,” Smith told Seeker. “I think the significance of the find still hasn’t quite dawned on me.”
The teeth belonged to the earliest mammal ancestors of all humankind, according to a paper on the findings published in the journal Acta Palaeontologica Polonica.
Analysis of the fossils determined that the teeth are the earliest, undisputed remains of mammals belonging to the lineage that led to Homo sapiens. They are also ancestral to most mammals alive today, including species as diverse as the blue whale and pygmy shrew.
In fact, the mammals during their lifetimes looked a bit like shrews, lead author Steven Sweetman, also from the University of Portsmouth, told Seeker.
“Almost all Mesozoic mammals were shrew to rat sized, and their body plans are known from skeletons discovered in other parts of the world, including China where soft tissues are also preserved,” Sweetman explained.