A revolution in evolutionary studies has begun with the extraction of fossil proteins from a rhinoceros tooth dating back to 1.77 million years ago: the oldest and most extensive genetic information recorded to date, being one million years older than the most ancient DNA ever sequenced.
An international research published in Nature - to which contributed the Department of Earth Sciences of University of Florence - reports on the findings that mark a turning point in the field of molecular paleontology studies. ["Early Pleistocene enamel proteome sequences from Dmanisi resolve Stephanorhinus phylogeny" doi: 10.1038 / s41586-019-1555-y]. The study, coordinated by Enrico Cappellini of the University of Copenhagen, is based on the analysis of fossil remains, in particular the dental enamel, of an extinct rhino (Stephanorhinus) that lived in Eurasia during the Pleistocene. The fossil remains are from the site of Dmanisi, in Georgia, where an international research group is working. The team includes professors from the University of Florence among which Prof. Lorenzo Rook who coordinates the studies on fossil mammals (with the support of the Italian Ministry of Foreign Affairs).
Dental enamel is the hardest tissue present in the mammal skeleton, and it is abundant in the fossil record. In this study, researchers revealed the set of fossil proteins preserved in the dental enamel lasts much longer than DNA (limited to the last 700,000 years), and is genetically more informative than collagen, the only other protein extracted to date from fossils older than one million years.
"The case study with which the fossil protein method is presented, which goes alongside and stretches even further back than the study of ancient DNA", explains Lorenzo Rook, professor of Paleontology and Paleoecology at the University of Florence, "allows us to have a clearer picture on the evolutionary history of one of the mammals at high risk of extinction (the rhino) thanks to the rigorous molecular control of the hypotheses that reconstruct the relationships between extant mammals and their fossil ancestors, using molecules different from the DNA."
"An essential requirement for analysis and sequencing of fossil proteins, thanks to mass spectrometry, is the accurate determination of the fossil species sampled. For this reason, the paleontologist's role is crucial to ensure a solid basis for genetic analysis" says Luca Pandolfi, paleontologist at the University of Florence, who carried out the anatomical and morphological study of the rhinos found at Dmanisi, a very important paleontological site since it also documents the oldest human presence outside the African continent.
"The potential of the research method based on fossil proteins is wide. This new method can be applied to many other animal species, including human fossil forms, and therefore it can contribute to the study of our evolutionary history," concludes prof. Rook.
