Seemingly Ordinary Fossils May Be Hiding Some Major Clues to the Past
Paleontologists are lucky to find complete sets of fossilized bones. Sometimes, they get even luckier, finding preserved impressions of delicate features like feathers. Beyond those clues, though, most of the biology of extinct species — their DNA, internal organs, and unique chemistry — has been totally destroyed by the many millions of years that separate us. Except, what if it hasn’t? Some scientists now claim they can tease much more complex biological information out of apparently mundane fossils, including things that most paleontologists don’t expect to survive over millions of years, such as skin and eggshell.
Molecular paleobiologist Jasmina Wiemann has been on the forefront of this exciting research since 2018, co-authoring papers that reveal elements of fossils that cannot be immediately seen with our eyes but can be detected through a series of complex chemical and statistical analyses. Her recent paper, published this summer with Jason Crawford and Derek Briggs, builds upon other, similar research from the past two years. She and her co-authors claim they can determine the chemical signatures of skin, bone, teeth, and eggshell. Even better, they can train anyone else in the field within approximately 20 minutes to find these ancient traces using their techniques. It’s an opportunity they hope will be widely used within museum collections the world over.
Consider that most museums only display a small percentage of the fossils they have in their collection. Those fossils chosen for display are either partially complete skeletons or fossils that are readily recognizable to the general public. What remains in many collections’ storage rooms are shelves upon shelves of the rest: the less-flashy fossils that nonetheless offer insight into ancient life. What if they all could be tested for hidden biomarkers?
It takes a specific set of circumstances for something to survive thousands of years, much less millions. And if it does become fossilized, think about the incredible pressure and heat it undergoes over eons. While it’s remarkable that bones and other hard tissues survive, it is currently assumed that less hardy structures, such as cells, blood vessels, skin, and their molecular building blocks, will not, especially after hundreds of millions of years.
Biomolecules — the chemical building blocks for which these scientists search — are the molecules that make up all animal tissues: proteins, lipids, and sugars. The specific fossilization products of biomolecules indicate to which kind of animal a fossil tissue once belonged, if it was biomineralized, and exactly what type of tissue it represents.
“Until now, it was assumed that biological signals preserved in modern biomolecules were lost during fossilization,” explained Wiemann in a phone interview. “Our study represents the very first exploration of original biosignatures in complex, fossil organic matter. Contrary to previous targeted analyses, we wanted to objectively explore if there are any signals preserved and what they can actually tell us about a fossil organism.”
In other words, rather than search for a specific molecule on one particular fossil, they wanted to determine what molecules — if any — were on the sample set of fossils they explored. What they consistently discovered was that traces of certain ancient molecules survived, chemically altered but still distinct. The team could identify different types of molecular fossils, and they could interpret their biological meaning.
“When we published our first paper on molecular preservation in 2018, we found evidence not only of the fossilized products of lipids, as previously reported, but also of the fossilization products of proteins and sugars,” Wiemann said. “This was a surprise to the field, and a very bold claim back then, especially because many previous case studies on fossil organic matter were affected by sample contamination. Now, two years later, our results have been reproduced multiple times by different laboratories, adding independent support to the fossilization potential of biomolecules through chemical transformation.”
Wiemann brings a different perspective to paleontology. At the age of 15, she won a scholarship in Germany to study chemistry, which enabled her to complete degrees in geosciences and evolutionary biology before attending Yale University, where she is currently a PhD candidate. In the past two years, she has discovered egg color in dinosaurs, contributed to research offering further evidence that the Tully Monster (Tullimonstrum) is a vertebrate, and helped reveal evidence that soft-shelled eggs evolved in dinosaurs before calcified eggshells. Translating the ancient chemical properties associated with those fossils was her role. As she explained, “I develop molecular proxies for all kinds of evolutionary topics to unlock information otherwise inaccessible to paleontologists.”