Genetics Link T-Rex to Chickens

In Jurassic Park, the ferocious Tyrannosaurus Rex tears through the island, crushing everything in its path and flinging around raptors and unlucky humans.

But a study in the current issue of Science magazine showed that the king of dinosaurs is related to some animals that might not usually be considered ferocious—like the chicken and the ostrich.

The study used data collected from a T. Rex femur bone found in 2003 that “was really special because it preserved soft tissue,” said John M. Asara, one of the authors and the director of the mass spectrometry core at the Harvard-affiliated Beth Israel Deaconess Medical Center.

In 2005, the researchers started to work on the bone, and last year, they were able to publish a small set of sequences from the collagen protein.

The bone was processed in a lab at North Carolina State University, and extracts were then sent to Asara and his colleagues, who sequenced them using mass spectrometry.

In this study, the researchers obtained collagen sequences from 21 critical species and used sophisticated algorithms to create an evolutionary tree that included the T. Rex and the 21 other species.

“We pieced all the sequences back together and realized that these sequences were looking more like chicken and ostrich,” Asara said, adding that it’s not clear whether T. Rex was more closely related to the chicken or the ostrich.

It is clear from the species tree that reptiles are not connected to the group that includes the T. Rex, a theory that had already become widely accepted based on the studies that examined the dinosaur’s bone architecture.

“If the T. Rex had popped out somewhere else—say our analysis grouped it with humans—our conclusion would be that we either screwed up the analysis real badly or the sequence from the T. Rex wasn’t authentic and there was contamination from some of the workers that sequenced the proteins,” said Chris L. Organ, a postdoctoral fellow in organismic and evolutionary biology and a co-author of the study.

He added that while the results of the study didn’t clarify any of the evolutionary relationships, they strengthened existing conclusions by using molecular evidence as opposed to bone structure.

“It really sort of suggests that it is possible to get sequences from something as old as 16 million years, if not older,” Asara said. “The sequences, even though they’re very short, can be used to make evolutionary relationships.”

—Staff writer Alissa M. D’Gama can be reached at adgama@fas.harvard.edu.

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