Forget Mosquitoes in Amber. Scientists May Have Found Dinosaur Blood in a 115 Million-Year-Old Bone.

3 min readAt first glance, the news seems like the opening lines of a Jurassic Park sequel. In a study published in Proceedings of the National Academy of Sciences, an international team of scientists reports finding traces of heme, an organic molecule that helps blood carry oxygen, in the vascular canals of a 115-million-year-old dinosaur bone. The fossil comes from the leg of Aratasaurus museunacionali, a distant relative of Velociraptor that lived during the early Cretaceous.The fossilized bones were found in 2008 at a mine in the Romualdo Formation of northeast Brazil. The potential discovery of molecular evidence of blood inside the bones would be remarkable because, simply put, blood doesn’t usually stick around very long after death.“Detection of endogenous biomolecules in vertebrate fossils remains controversial because labile compounds degrade quickly and are highly susceptible to contamination,” the authors write in the study. “By identifying heme-derived molecules—key components of blood—and confirming their spatial association, the study reduces the likelihood of contamination.”Previous claims of fossilized blood cells have mostly stumbled over the same two problems: contamination, and the difficulty of ruling out structures that only look biological. According to Science, at least 14 previous studies have claimed to find evidence of dino blood, but none have been robust enough to convince the scientific field at large, though one paleobiologist, speaking with Science, says this new study is “the most comprehensive effort that’s been done so far.”The story of this particular fossil is a harrowing one as it is the lucky survivor of a 2018 fire that destroyed the National Museum at the Federal University of Rio de Janeiro. In fact, its scientific name means “the dinosaur born from the National Museum fire.” Although the bones were not particularly well preserved, Curtin University’s Kliti Grice and a team of researchers from the U.S., Japan, and Brazil analyzed the fossils using liquid chromatography–mass spectrometry, Raman spectroscopy, and transmission electron microscopy.STR//Getty ImagesPeople watch as a massive fire engulfs the National Museum in Rio de Janeiro, one of Brazil’s oldest, on September 2, 2018.Together, these techniques detected heme (a key component of hemoglobin) inside the bone’s vascular canals, but not in the surrounding rock. That contrast is key, because it suggests the heme came from the dinosaur and didn’t seep in from its surroundings. Cell-like structures in the surrounding sediment, by contrast, were dominated by compounds derived from chlorophyll, a sign of plant or microbial origin.“A key question was whether the structures we saw were really biological remnants—that is, actual blood—or something that may have happened to the fossil later as the tissues were turning to stone,” Grice wrote in an article for The Conversation. “We evaluated and ruled out several alternative explanations for the structures. In the end, we believe they’re most likely authentic fossilised red blood cell remains.”But for a substance that’s famously finicky about fossilization, how did evidence of blood remain within these vascular canals for 115 million years? Well, like most ancient bones that survive to this day, it’s all about dying in the right conditions. As this dinosaur traipsed around what’s now northeast Brazil—at a time when the landmass was still physically connected to Africa—it died and sank into a watery, low-oxygen grave where mats of microbes grew over the top. According to Grice, the additional presence of the mineral hausmannite, which can act like an antioxidant, might’ve also slowed down the decay. Eventually, the blood cells mineralized much like the vascular channel and the bones themselves.“The fossil red blood cell-like structures appear a bit larger and more rounded than the cells found in modern birds and crocodilians,” Grice writes. “It could suggest the red blood cells of dinosaurs not related to birds were shaped differently than those of birds, their modern relatives.” However, North Carolina State University paleontologist Mary Schweitzer tells Science that this difference in blood cell shape—as well as the lack of a nucleus in the cell—is too radical a departure from birds and crocodilians, suggesting these structures aren’t blood cells at all.Grice says that all indications, whether from microscopy, mineralogy, spectroscopy, or molecular geochemistry, point to the first-ever discovery of molecular evidence of dinosaur blood. But as past studies have shown, it might take more evidence to win over the field at large.Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.