Iron-bearing traces in a Brazilian dinosaur leg may point to 115-million-year-old blood cells
An Australian team found round structures containing heme residues in the vascular canals of a small predatory dinosaur, but other researchers remain sceptical.
Researchers led by organic geochemist Kliti Grice (Curtin University, Australia) report in the journal PNAS that they may have found remains of red blood cells in bones of Aratasaurus museunacionali. This small carnivorous dinosaur lived around 115 million years ago in what is now north-eastern Brazil. The fossils were found in a mine in 2008 and are kept at the National Museum of Brazil, VRT NWS writes.
Using a powerful electron microscope, the scientists saw small oval structures of about 23 by 20 micrometres in the canals where blood vessels once ran, Sci.News reports. Chemical analyses revealed heme, the iron-containing part of haemoglobin, along with its breakdown products. According to the authors, no intact proteins or blood survived. The animal was probably buried in shallow, oxygen-poor water, and the manganese mineral hausmannite may have aided preservation.
Palaeontologist Mary Schweitzer (North Carolina State University), who earlier found soft tissue in dinosaur fossils, is not convinced, according to VRT NWS: the structures are hollow, whereas dinosaur red blood cells should bulge near the nucleus. Grice herself also urges caution and wants to test the method on other fossils. The aim is to learn how much molecular information fossils can retain, not to find DNA for cloning, she stresses.