Researchers have identified mineralized red blood cells and intact heme biomolecules in the limb bones of a 115-million-year-old theropod dinosaur, Aratasaurus museunacionali, recovered in northwestern Brazil. The study, published in Proceedings of the National Academy of Sciences, also found preserved collagen amino acids.
The bones contained numerous red blood cell structures inside vascular canals. Although earlier research had reported possible fossilized blood cells, the team says this is the first time chemical evidence has confirmed hemoglobin-derived molecules within such cells. The samples preserved heme, the oxygen-carrying component of hemoglobin, providing evidence of fossilized blood remains.
The cells were mineralized with hausmannite, a mineral that helped stabilize their structures and biomolecular components over millions of years. The researchers believe the dinosaur was rapidly buried in a low-oxygen, microbially rich environment soon after death, contributing to the exceptional preservation.
Kliti Grice, founding director of Curtin University's WA-Organic and Isotope Geochemistry Centre and the study's lead author, described the detection of intact heme-derived molecules in 115-million-year-old cells as a landmark discovery. She said the finding extends the fossil record of blood and provides a molecular view of the physiology of extinct animals.
The research involved scientists from Curtin University's School of Earth and Planetary Sciences, the Japan Agency for Marine-Earth Science and Technology, Brazil's National Museum and Regional University of Cariri, and Johns Hopkins University. According to the team, the results challenge the assumption that molecules such as hemoglobin cannot survive deep time and could support further research into blood evolution, metabolism and activity levels in ancient animals.
Martin Van Kranendonk, head of Curtin's School of Earth and Planetary Sciences, said the findings could also inform astrobiology by showing how molecular structures may remain preserved over long periods or under hostile conditions. The study is titled "Heme signatures in mineralized red blood cells within vascular canals of a 115-million-year-old dinosaur bone" and has been published with DOI 10.1073/pnas.2614248123.
Sources: Phys.org.