September 4, 2006 | David F. Coppedge

Dinosaur Bone Hunting Looks Promising

With probably less than a third of dinosaur types known, prospects are good for a new generation of young people to find one of their own, reports News@Nature.  New finds in Mongolia, South America and China over the last fifteen years indicate the vast majority of dinosaurs are still waiting to be discovered.  The authors of a study in PNAS1 found that 14.8 new genera have been found per year since 1990, more than double the rate in the prior 20 years; in conclusion, they estimate that 71% of dinosaur genera remain to be found.  They also claim that the dinosaurs were not in decline before their extinction.  See also the 04/25/2006 story.
    With soft tissue evident in some dinosaur bones (see 02/22/2006), does this raise the possibility of cloning a dinosaur and building Jurassic Park?  Svante Pääbo, an expert in sequencing ancient DNA, does not think so.  An interview in PNAS2 ended,

One doesn’t really know what may come in the future, but cloning an organism from a genome fragmented into small pieces of DNA will probably always be impossible,” [Paabo] says, “and from what we know about the chemical stability of DNA, sequence retrieval will always be on this side of a million years ago, so dinosaur DNA is beyond our reach.”  The problem, he says, is that DNA is extremely hydrophilic, and exposure to water molecules as well as atmospheric oxygen and background radiation breaks it down.  Even under highly favorable preservation conditions, such as mummies in a dry and cold desert, DNA disappears from a specimen within a few hundred thousand years.  However, even given such limitations, many interesting discoveries still lie in ancient DNA.

1Steven C. Wang and Peter Dodson, “Estimating the diversity of dinosaurs,” Proceedings of the National Academy of Sciences, USA, 10.1073/pnas.0606028103, published online before print September 5, 2006.
2Nick Sagorski, “Profile of Svante Pääbo,” Proceedings of the National Academy of SciencesUSA, 10.1073/pnas.0606596103, published online before print September 5, 2006.  In his last comment, he’s thinking of Neanderthal DNA, his current specialty.

National Geographic reported on this paper after we did.  As usual, their write-up provides a good chance to practice separating data from interpretation.
    Now that we know soft tissue and possibly blood cells can be preserved in dinosaur bones, there should be plenty of material to look in.  The second article made a prediction: DNA is too fragile to be found at all after a few hundred thousand years.  What if some day dinosaur DNA is found that can be sequenced?  Here is a great contest for scientists with an open mind.  Children who like dinosaurs should be encouraged to grow up and join the hunt.  We should never think that all the exciting scientific discoveries are behind us.

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Categories: Dinosaurs, Fossils

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