By Sohaib Shams
Scientists have identified fossilized red blood cells and traces of heme in the hind leg bone of an Aratasaurus, a small meat-eating dinosaur that lived in what is now northeastern Brazil 115 million years ago.
The research, led by Prof Kliti Grice at Curtin University in Western Australia, used electron microscopy and chemical analysis on fossils held at the National Museum of Brazil since their discovery in a mine in 2008.
Images revealed small, round structures in fine channels where blood vessels once ran, while tests confirmed the presence of heme, the organic compound that enables haemoglobin to carry oxygen, as well as amino acid building blocks for collagen.
The findings, published in Proceedings of the National Academy of Sciences, represent the first in situ detection of fossilized red blood cells with heme-related chemistry in any fossil, according to Grice.
Scientific Debate
The claim has sparked debate. Prof Mary Schweitzer of North Carolina State University, known for previous discoveries of soft tissue in dinosaur fossils, questions whether the structures are truly red blood cells, noting they appear concave rather than the expected dome-like shape with a nuclear bulge.
Schweitzer acknowledged the heme and collagen evidence as more persuasive and said the study challenges the long-held view that endogenous organics disappear within a million years.
Preservation Mechanism
Grice suggests that a manganese compound called hausmannite, which formed in and around the blood cells, may have stabilized them before fossilization, potentially preserving the amino acids as well.
Implications for Fossil Collections
The researchers caution that the discovery does not imply survival of large molecules such as proteins or DNA, but it raises the possibility that exceptional molecular information may already exist in museum collections worldwide, awaiting new analytical techniques.
