Paleontology has just reached a major milestone with the discovery of intact proteins in fossils dating back to the Miocene.
This breakthrough, published in Nature, is based on the analysis of fossilized rhinoceros teeth from two contrasting sites: the Canadian Arctic and the arid Turkana Basin in Kenya. Researchers have identified protein sequences dating back 18 to 24 million years, far exceeding previous records.
Ancient rhinoceros tooth.
Image: University of York Tooth enamel, a molecular vault
Tooth enamel has proven to be an exceptional medium for protein preservation. Its rigid mineral structure protects organic molecules from degradation, even in hostile environments. In Kenya, high temperatures did not prevent their preservation.
The extracted proteins have enabled the reconstruction of evolutionary links between extinct species and their modern descendants. For example, an Arctic rhinoceros was found to belong to a distinct lineage, challenging some previous classifications.
These findings confirm that proteins are much more resilient than DNA, which rarely survives beyond one million years. They open the door to studying ancient species whose genetic material was previously considered lost.
New connections in evolutionary history
The analyses have revealed unexpected evolutionary divergences. The Arctic rhinoceros, for instance, would have split from other species 41 to 25 million years ago, much earlier than morphological studies suggested.
Researchers now plan to apply these methods to other groups, such as early hominids. Proteins could shed light on mysteries such as the origin of hippopotamuses or the evolution of mammals after the extinction of dinosaurs.
This work also shows that diverse environments, from polar cold to scorching deserts, can preserve biomolecules. This diversity significantly expands the areas suitable for future discoveries.
Article author: Cédric DEPOND