Forget Mosquitoes in Amber: Scientists Find Dinosaur Blood Traces
An international team reports heme, a blood-carrying molecule, in a 115-million-year-old dinosaur bone from Brazil. The study in Proceedings of the National Academy of Sciences says the find is the most comprehensive effort so far, though earlier blood claims have not convinced the field.
Scientists have reported finding traces of heme, a molecule that helps blood carry oxygen, in a 115-million-year-old dinosaur bone from Brazil, in a study published in Proceedings of the National Academy of Sciences. Forget mosquitoes in amber: this time the evidence sits inside the bone itself.
It sounds like the opening of a Jurassic Park sequel. The claim is also contested ground.
What the team found
An international team detected heme in the vascular canals of a leg bone from Aratasaurus museunacionali. The animal was a distant relative of Velociraptor that lived in the early Cretaceous. The fossil was found in 2008 at a mine in the Romualdo Formation of northeast Brazil.
Curtin University's Kliti Grice and researchers from the U.S., Japan and Brazil analyzed the bone. They used liquid chromatography–mass spectrometry, Raman spectroscopy and transmission electron microscopy.
Heme showed up inside the canals but not in the surrounding rock. That contrast suggests the molecule came from the dinosaur rather than seeping in from outside. Cell-like structures in the surrounding sediment were dominated by compounds derived from chlorophyll, a sign of plant or microbial origin.
A fossil that survived a fire
The specimen survived a 2018 fire that destroyed the National Museum at the Federal University of Rio de Janeiro. Its scientific name means "the dinosaur born from the National Museum fire." The bones were not particularly well preserved.
Why blood is hard to prove
Blood rarely lasts after death. The study's authors write that detecting original biomolecules in vertebrate fossils "remains controversial because labile compounds degrade quickly and are highly susceptible to contamination." They say confirming where the heme sits "reduces the likelihood of contamination."
Earlier claims have stumbled on contamination and on structures that only look biological. According to Science, at least 14 previous studies have claimed evidence of dinosaur blood, but none convinced the wider field. One paleobiologist told Science this is "the most comprehensive effort that's been done so far."
Grice wrote in an article for The Conversation that the team ruled out several alternative explanations. "In the end, we believe they're most likely authentic fossilised red blood cell remains," she wrote.
How it may have survived
Grice says the animal died and sank into a watery, low-oxygen grave where mats of microbes grew over the top. The mineral hausmannite, which can act like an antioxidant, may also have slowed decay. The blood cells then mineralized, much like the vascular channel and the bones.
The fossil red blood cell-like structures look a bit larger and more rounded than cells in modern birds and crocodilians, Grice writes. That could suggest dinosaurs not related to birds had differently shaped red blood cells than their modern relatives.
