Organic material from a T. rex bone shows that birds are the closest living relatives of dinosaurs.
In echoes of Jurassic Park, organic material has for the first time been recovered from a dinosaur fossil. Protein fragments from a 68 million year old T. rex bone most closely match samples from a chicken, providing further evidence of the evolutionary relationship between dinosaurs and birds.
"Analyses of Soft Tissue from Tyrannosaurus rex Suggest the Presence of Protein" by Mary Higby Schweitzer and others, Science (volume 316), April 13, 2007, pages 277-280.
Duration: 3 minutes, 25 seconds
Posted: April 20, 2007
Jan Witkowski: Welcome to DNA Today, Iâm Jan Witkowski.
Dave Micklos: And Iâm Dave Micklos. Welcome to Cold Spring Harbor Laboratory where we are discussing news about DNA.
JW: And todayâs news comes, in a way, from a very long time ago. It is about a fossil 68 million years old, a T-Rex. And the research could have come straight out of Jurassic Park. As you remember Dave, in Jurassic Park, they isolated DNA from fossils bones and cloned dinosaurs. This isnât quite as exciting as that, but scientists have been able to isolate protein from these very, very old bones.
DM: And this work built on earlier work from several years ago when, using a microscope, scientists were able to figure out that some of these dinosaur bones, T-Rex bones, for example, preserve flexible features inside the bone, including perhaps, blood vessels and even single cells. Then, the next step, which was accomplished recently, was to extract protein from these bones and the protein that was extracted was, in fact, collagen.
JW: Yes, I mean this was clearly an exceptional fossil â that this protein had been preserved for so many years. But even so, it was pretty degraded, that is, it had been destroyed, partially destroyed. It had to be analyzed by a technique called mass spectrometry. This enables you to determine what amino acids there are in small fragments of protein, in small peptides. And the researchers did this, and then they compared the sequences of amino acids that they had found in the dinosaur collagen, with the same sequences from living organisms.
DM: And thatâs where they found something that was quite extraordinary. When they compared the amino acids sequence from the T-Rex bone versus sequences in databases from living organisms, they found that the closest match was a chicken.
JW: But why was this such an unexpected find?
DM: Well, in a sense it wasnât unexpected because for the last several decades, most paleontologists have believed that, in fact, birds, such as chickens, are living relatives of dinosaurs. Ironically, this thinking that birds might be evolutionarily related to dinosaurs cropped up in the mid 1800s. Thomas Huxley proposed this shortly after Darwin published The Origin of Species. That idea was revived in the 1920s, it got a lot of support in the 1960s when analysis of therapod bones, of which T-Rex is a member of that group, reveal that there are a lot of anatomical similarities between birds and dinosaurs.
JW: Now, this was protein.
DM: This was protein.
Both: What about DNA?
JW: Well, in fact, the DNA has really only been isolated from fossils maybe 100,000 years old. So, the chances of finding DNA in this very old fossil are pretty unlikely. But then, before this paper, people wouldnât think you could even get protein from such an old fossil. So, maybe in the years to come we will really be able to go to a Jurassic Park.
DM: Just have a strong fence.
dinosaur fossil, protein fragments, tyrannosaurus rex, evolutionary relationship, t rex, higby, soft tissue, jurassic park, dinosaurs, echoes, birds, relatives, Dave Micklos, Jan Witkowski
- ID: 16880
- Source: DNALC
- Download: mp4
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