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Mineralized red blood cell remnants retain heme chemistry in Aratasaurus bone
The dinosaur lived during the Early Cretaceous epoch, some 115 million years ago, an age estimate given for this species in the Sci.News account of the work.
Mineralized remnants of red blood cells that retain heme chemistry have been identified in hind-limb bone of Aratasaurus museunacionali, a coelurosaurian theropod from what is now northeastern Brazil.
The work centers on fossils from the Mina Pedra Branca site of the Romualdo Formation, a unit known worldwide for the large number of well-preserved specimens. Curtin University’s Professor Kliti Grice and colleagues examined the animal’s hind-limb bones. Their 2026 paper in the Proceedings of the National Academy of Sciences gives an age estimate of some 115 million years ago for this Early Cretaceous Aratasaurus museunacionali material.
Inside the bones’ vascular canals, the channels that once carried blood vessels, the paleontologists identified numerous tiny, ellipsoidal structures. Sci.News reports that those structures average about 23 micrometers in length and 20 micrometers in width.
Scanning electron microscopy has imaged the red blood cell-like structures in the bone. Within that material the team detected heme B, a molecule central to the oxygen-carrying function of hemoglobin, together with a chemically altered derivative known as 3,8-diethyl heme B. Further imaging and spectroscopic analyses located heme-related chemical signatures within the same structures, strengthening the interpretation that they are mineralized remnants of red blood cells. Sci.News.
Grice, first author of the study, said the findings challenge longstanding assumptions that certain biomolecules such as hemoglobin cannot survive deep time, and that the result opens avenues for molecular-level paleontology aimed at the evolution of blood, metabolism and activity levels in ancient animals.
The scientists suggest that manganese oxide mineralization, particularly the mineral hausmannite, helped protect the cellular structures and their organic contents from degradation. Grice and colleagues do not conclude that intact blood or hemoglobin proteins survived for more than 100 million years.