The T. rex Collagen Controversy

T. rexIn 2007, a group of investigators, led by John Asara of the Beth Israel Deaconess Medical Center and Mary Schweitzer of North Carolina State University, announced in Science that they had sequenced collagen from a 68 million-year-old Tyrannosaurus rex by mass spectrometry. The T. rex was the oldest fossil to date to have its protein sequenced. On the basis of data collected from seven peptides, the authors concluded that the T. rex's collagen resembled that of chicken. But as the headlines about the T. rex–chicken link hit major newspapers, so did questions about the work. Getting sequence data from fossils aged 1 million years or older has been the Achilles’ heel of the molecular paleontology field. So when Asara, Schweitzer, and colleagues reported they had identified, sequenced, and taxonomically classified a protein from a 68 million-year-old dinosaur, it obviously made other experts curious as to how they managed to do it. Scrutiny of the paper followed. The controversy over this high-profile paper has been brewing for the past 18 months and likely won't die any time soon. The raw mass spectra that Asara and colleagues collected are now available on the publicly accessible PRIDE database so that others can assess whether or not the data and original conclusions are sound. Image: Shutterstock
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  1. I hope someone dares to consider the obvious answer to the question about how they “identified, sequenced, and taxonomically classified a protein from a 68 million-year-old dinosaur”. That answer: Maybe the dinosaur is less than 1 million years old! After all, 68 million years should be one or two orders-of-magnitude longer than required to decompose collagen, even when trapped inside of bone & rock. The fact that collagen is present in a T. rex bone should shake the theory of evolution off its very foundation!

  2. “…68 million years should be one or two orders-of-magnitude longer than required to decompose collagen…”–Mr. Stanley

    The environment in which of mortal remains are buried plays a far greater role in fossil fidelity than time. Bone exposed to sunlight disintegrates in decades, but buried under ideal conditions it can last for 250 million years or more; that’s the very nature and capricious beauty of fossilization.

    “Maybe the dinosaur is less than 1 million years old!”–Mr. Stanley

    The age of the tyrannosaur bone is established using its position within the stack of sedimentary layers. This stack forms like a series of snowfalls, with the oldest at the bottom and progressively younger layers toward the top. The age of some layers, particularly those produced by volcanoes, can be measured directly using radioisotopes. The tyrannosaur lies in a sediment layer between two of these dated ash units, allowing us to pinpoint its age to the nearest half-million years or so. Tyrannosaurus rex fossils appear only in rocks within the stack that are 65 to 68 million years in age.

    “The fact that collagen is present in a T. rex bone should shake the theory of evolution off its very foundation!”–Mr. Stanley

    Organic residues are common in fossil remains. They, like mineral remains such as vertebrate bone or invertebrate aragonite shells, can be preserved under ideal environments; even vegetable matter has been preserved under ideal circumstances, to be mined today as coal or oil. Typically, however, the process of fossilization breaks down organic molecules, leaving only components or segments; this research is remarkable in that, if accurate, the results suggest the breakdown of collagen was incomplete enough in this tyrannosaur femur to identify original pieces of it. The preservation of organic material in this dinosaur bone indicates nothing about its age, the age of the Earth, or the process under which the dinosaur came to be.

    Dr. Will Straight, paleontologist
    Northern VA Community College

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