Paleontologists have isolated cartilage cells from an exceptionally well-preserved dinosaur fossil in China. Cell nuclei still contain traces of biomolecules and other organic structures, and scientists are even able to tell what stage in the natural cycle specific cells were at when they died.
Bones are usually all we have left to work on when rebuilding dinosaurs, but sometimes scientists are lucky and find more. Feathers, skin, eggs, and even brains have been discovered, revealing new insights into these amazing animals.
Some of the best-preserved specimens come from Jehol Biota, an early Cretaceous ecosystem in northeast China. The landscape was dominated by wetlands and shallow lakes, and especially frequent volcanic eruptions which were essential in slowing the decomposition of the remains.
“Geological data has accumulated over the years and has shown that the preservation of fossils in Jehol Biota is exceptional due to the fine volcanic ash that buried the carcasses and preserved them down to the cellular level,” Li Zhiheng explains. , co-author of the study.
It was in this deposit that researchers from the Chinese Academy of Sciences and the Shandong Tianyu Nature Museum collected the last astonishing specimen, dated to around 125 million years ago. The creature in question is called Caudipteryx, a bird-like dinosaur that stood knee-deep and sported long tail feathers.
The team extracted a section of cartilage from his right femur and found that he had undergone a type of fossilization known as silicification. The original organic tissue has been replaced with silica, which helps preserve cells.
In fact, the preservation was so complete that the researchers were able to differentiate between cells that were healthy at the time of death from those that were already dying, due to the natural cell cycle.
After researchers demineralize part of the sample, they stained it with a chemical called hematoxylin, which binds to a cell’s nucleus and appears purple. And of course, one of the dinosaur cartilage cells reacted in exactly the same way as a chicken cartilage cell: it turned purple, highlighting the nucleus and chromatin threads, structures that make up chromosomes. .
Oddly enough, the nucleus and chromatin are where DNA molecules are found inside cells. This suggests that some dinosaur DNA remains could potentially be kept inside, but it’s a long way and will take a lot more work to verify. After all, we don’t think DNA survives more than a million years, let alone 125 million.
“Let’s be honest, we are obviously interested in fossilized cell nuclei because that is where most of the DNA should be if the DNA was preserved”, explains Alida Bailleul, co-author of the study. So we have good preliminary data, very interesting data, but we are just starting to understand cellular biochemistry in very old fossils. At this point, we need to work more.
This isn’t the first study to find evidence of cell nuclei and potential DNA in dinosaur fossils. Last year, a team, including some of the scientists from the new study, discovered signs of nuclei, proteins and chromosomes in the cells of a large herbivore called Hypacrosaurus, found in Canada. However, the Caudipteryx specimen is around 50 million years old.
The research was published in the journal Communications biology.
Source: Chinese Academy of Sciences