Dinosaur cells have been recovered in China that seem to tentatively hint that dinosaur DNA remnants may also survive to this day.

About 125 million years ago, a small dinosaur with a long, feathered tail walked along the shores of a lake in what is now northeastern China. For some reason it became the dinosaur’s last walk; he died on the edge of the lake. And if that wasn’t enough, a volcano erupted a short distance away, covering the animal’s remains with a thick blanket of ash.

special item

This makes the story of this dinosaur – belonging to the genus Der caudipteryx – maybe to be finished. But nothing is less true; millions of years later, researchers have rediscovered this dinosaur. That in itself is not so special; remains of dinosaurs are regularly excavated in China – but also beyond. And yet this specimen is unique. Because thanks to that ash blanket, researchers have now found a cell nucleus in perfectly preserved cartilage cells. “Let’s be honest,” said researcher Alida Bailleul. “Of course we are interested in fossilized cell nuclei, because that is where most of the DNA – if that is also preserved – is found.”

It is currently unclear whether this cell nucleus also contains DNA. But where until recently it was actually considered impossible that dinosaur DNA could have been preserved, this find indicates that this is indeed a possibility. This is because remnants of organic molecules and chromatin have been found in the cell nucleus. The latter is particularly interesting; Chromatin is a complex of DNA and proteins. It therefore cautiously hints that dinosaur DNA might still stand the test of time. “Parts of the original organic molecules have certainly been preserved in the nucleus,” Bailleul explains Scientias.nl. “Maybe some original DNA too, but we’re not sure yet.”

Cartilage

The researchers stumbled upon the cell nucleus when they examined a piece of cartilage from the dinosaur’s right femur. They soon discovered that the cartilage actually housed two types of cells: cells that were healthy when the dinosaur fossilized and cells that were dying at the same time. “It’s possible that these cells were already dying when the animal died,” Bailleul said. It is not very surprising that the researchers have discovered dying cells; it is common for cells to die during the life of their host. What is special is that for the first time, paleontologists are now able to determine whether fossilized cells were healthy or dying.

nucleus

The researchers went one step further. They isolated some of these cells and stained them with a chemical, purple, that binds to cell nuclei. Subsequently, a purple-colored cell nucleus with a few dark purple threads became visible in one of the cells. It revealed that this 125-million-year-old cell had a nucleus that had turned out to be so well-preserved that it still contained the organic molecules and chromatin fibers.

Exciting

Bailleul mentions the preliminary results “exciting”. “But we are just beginning to understand the cellular biochemistry in very ancient fossils. We have a lot more work to do.” For example, the question remains how DNA – if indeed it can survive more than 100 million years – will stand the test of time, how we can prove its presence in such ancient fossils and what we can still do with that DNA. “I think if there are any DNA or DNA-like molecules in this cell nucleus, they are chemically very, very modified, with cross-links everywhere,” Bailleul says. “We probably won’t be able to sequence it either.”

Jurassic Park

And yet the idea that dinosaur DNA may have been partially preserved left or right is causing great excitement. The general public will undoubtedly immediately think of Jurassic Park: the film in which people against their better judgement set up a zoo full of cloned dinosaurs with the help of a little dinosaur DNA. But that remains fiction, Bailleul assures us. “There will never be a real Jurassic Park. Even if we can sequence their entire genome, we won’t be able to clone dinosaurs and bring them back to life like they do in Jurassic Park.”

Information

The suggestion that dinosaur DNA may have withstood the test of time has excited some scientists for very different reasons. Because we know from considerably younger DNA – such as that of mammoths and other extinct animal species, including hominids – that it can provide a wealth of information.

Criticism

However, not everyone is enthusiastic; some researchers have doubts about the idea that dinosaur DNA might still survive today. And it has also been suggested that the chemical Bailleul and colleagues used to detect the cell nucleus actually reacted not to dinosaur cell material, but to microbes entrenched in the dinosaur remains. Bailleul thinks otherwise. “We have yet to determine what exactly is in the nuclei of these dinosaur cells, but it certainly does not appear that the discoloration was caused by bacteria. We can really rule that out. They are original dinosaur cells and nuclei.”

Bailleul – who in 2020 also found something reminiscent of DNA in 50 million years younger dinosaur cells – remains enthusiastic. “It’s so exciting. Let the future, more data, more research and technological advancements tell us the full truth about preserving DNA from the distant past. I hope that one day we can somehow reconstruct a genome sequence. Let’s wait and see; I could be wrong, but I could also be right.”