DNA sequences from two non-avian dinosaurs
Studies of ancient DNA have revolutionized our understanding of extinct organisms, but thus far the maximum estimated age of sequenced DNA is two million years. However, evidence for endogenous biomolecules, including proteins, lipids, and pigments have been found in much older fossils, dating to up to 195 million years. Amino acid sequence data consistent with ancient, endogenous biomolecules have been derived from specimens of the theropod Tyrannosaurus rex (MOR 1125) and the hadrosaur Brachylophosaurus canadensis (MOR 2598). Histochemical and immunological studies also identified a molecule consistent with DNA in these two ancient specimens, localized to a single point within preserved osteocytes. Here we report the sequencing and analysis of DNA extracted from osteocytes and blood vessels of T. rex and B. canadensis, liberated after demineralization of dense cortical bone. Usable sequence reads were obtained at a low recovery rate. After the removal of high-quality reads that mapped to the human genome, the remaining reads were highly fragmented, with similarities to multiple animal species including reptilian and avian genomes. Our findings support the hypothesis that DNA and histone signal from imaging, mass spectrometry, and DNA sequencing of dinosaur osteocytes are endogenously preserved biomolecules. Overall design: 12 samples