The chicken is the closest living relative of the Tyrannosaurus Rex, according to a team led by North Carolina State University paleontologist Mary Schweitzer. The scientists who came to this conclusion did so through a process of sequencing proteins from a fossilized Tyrannosaurus Rex leg bone, finding that molecules from the 68-million-year-old fossil showed great similarity to those found in chicken. This research constituted the first evidence of molecular similarity between dinosaurs and modern-day birds, a connection that had previously been conjectured based on physical similarities.
Part of the reason why this research is so impressive is that paleontologists had long believed that any proteins or DNA that fossils may have once contained would have been destroyed over time. Schweitzer and her team were able to locate and use such genetic material for the first time in paleontological history in order to make an empirical connection between Tyrannosaurus Rex and the common chicken. Specifically, the team used collagen found in the bone to perform a molecular comparison that proved what had previously only been conjecture based on the fossil record. There is additional paleontological evidence to suggest that, rather than simply being covered in scaly skin, baby and perhaps even adult Tyrannosaurs were actually covered in feathers, much like their contemporary descendants.