A distant descendant of prehistoric giants: scientists have identified the closest living relative of the Tyrannosaurus rex.

The Earth is home to an incredible number of species: some have long been extinct, while others still inhabit the planet. Among the largest and most renowned animals globally, dinosaurs are considered significant: hundreds of millions of years ago, they roamed the Earth, standing atop the food chain, according to IFLScience.

But who are the closest relatives of these gigantic dinosaurs, and do they still live nearby? Back in 2008, scientists utilized proteins extracted from dinosaur bones to compare molecular data with modern animals. The concept was that dinosaurs might actually be related to birds. It’s worth acknowledging that this idea was not new, but science lacked evidence beyond anatomical similarities and skeletal data.

Researchers utilized 68-million-year-old Tyrannosaurus rex bones and extracted collagen, a protein also found in the bones of modern animals. This was already a remarkable discovery, as it demonstrated for the first time that collagen could survive for such an extended period. Moreover, this finding provided an unprecedented opportunity to analyze dinosaur tissues.

It should be noted that scientists detected collagen using a technology known as mass spectrometry, and the resulting peptide sequences could be employed in molecular analysis to identify similarities between the extracted sample and collagen from 21 extant species.

In the next phase of the research, scientists used the results to create genealogical trees that illustrated the relationship between the well-known T. rex and various groups of animals. The researchers noted that the trees were combined in numerous ways, producing different outcomes that were subsequently compared.

The results indicate that most researchers placed T. rex firmly within Archosauria, a group common to both birds and crocodiles, but leaned towards birds. In simple terms, the collagen from dinosaurs resembled that of chickens and ostriches more than it did that of crocodiles, which appeared dinosaur-like.

The authors of the study cautioned that their work has gaps that slightly obscure the complete picture. However, when asked about who the closest living relatives are, the scientists leaned more towards birds, specifically chickens or ostriches.

According to study author John Asara from Harvard University, their research effectively settled the debate on whether birds are dinosaurs. Throughout the study, the authors concluded that if similar biomolecules from non-avian dinosaurs were processed in the same way, they would also show a higher degree of similarity to birds than to any other vertebrates.

The genetic results from the scientists largely align with what has been observed in skeletal data. In simple terms, there is more than a 90% probability that the grouping of T. rex with living birds is accurate.