A team of scientists has successfully recovered a protein sequence from a 20-million-year-old rhino tooth, providing new insights into the deep evolutionary story of the species. These insights are not only helping us learn more about rhinos’ past, but also providing clues for how we can save the endangered species today.
The new study, published in Nature, is truly groundbreaking, with the fossilized tooth providing the oldest protein ever sequenced and expanding the boundaries of paleontology beyond where anyone thought they could go.
“This study is a game-changer for how we can study ancient life,” said Ryan Sinclair Paterson, postdoctoral researcher at the Globe Institute, in a press release.
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Unraveling the Rhino Family Tree with Ancient Proteins
Ancient rhino tooth (Image Credit: University of York)
University of York
Normally, scientists are forced to rely on a fossil's size and shape, or the collection of ancient DNA (aDNA), in order to learn more about extinct species. However, the use of aDNA specifically poses a major problem: it often doesn’t survive longer than one million years. Because of these roadblocks, it is difficult to learn more about the deep evolutionary past of many animals.
Ancient proteins have proven to provide a much bigger evolutionary window into the past, but they still have their setbacks. In the past, researchers have only been able to collect protein sequences from Middle-Late Miocene fossils, dated to the last 10 million years.
But with this rhino tooth, everything changed. The team was able to extract a protein sequence from the ancient rhino tooth and used a process called chiral amino acid analysis to expand their knowledge on rhino history.
“It is phenomenal that these tools are enabling us to explore further and further back in time. Building on our knowledge of ancient proteins, we can now start asking fascinating new questions about the evolution of ancient life on our planet,” said Marc Dickinson, co-author and postdoctoral fellow at the University of York, in the press release.
And what fascinating questions did this particular protein sequence answer? It showed that the species of rhino that belonged to the tooth split from other species during the Middle Eocene-Oligocene (41million to 25 million years ago). Additionally, the study rewrote rhino evolutionary history, suggesting that the two main subfamilies of rhinos — Elasmotheriinae and Rhinocerotinae — actually diverged from each other more recently than previously believed using bone analysis alone.
How Did This Fossil Survive So Long?
The key to this scientific leap lies in the fossil’s exceptional preservation. The rhino tooth was found in the Haughton Crater, located in the Canadian High Arctic. This location is characterized by permafrost and cold, stable conditions ideal for preserving delicate biological material.
“The Haughton Crater may be a truly special place for paleontology; a biomolecular vault protecting proteins from decay over vast geological timescales,” said Enrico Cappellini, from the Globe Institute, in the press release. “Its unique environmental history has created a site with exceptional preservation of ancient biomolecules, akin to how certain sites preserve soft tissues.”
The dental enamel of the ancient rhino tooth, combined with the cold environment, was the perfect combination to protect proteins for analysis. The team hopes this find will encourage other paleontologists to broaden their fieldwork sites, as they never know where the next fascinating fossil may be hidden.
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