In celebration of the approaching New Year, I present a list of my most popular science stories of 2009. Taken from the vast expanse of all fields of science, they may not be everyone's top ten, but they are among the top news makers and will have repercussions well past the ending days of 2009.
Of all the stories on the list, the so-called Paleocene dinosaurs have seen the most action in the academic world since the original story ran. The controversy the news riled up is not surprising. After all, claiming that large dinosaurs living in the San Juan Basin in New Mexico survived the mass extinction at the end of the Cretaceous period is a huge claim. Though perhaps not for obvious reasons.
“There's no reason, in theory, why there couldn't be Paleocene dinosaurs,” says Spencer Lucas, Curator of Geology and Paleontology at the New Mexico Museum of Natural History and Science. “But we should be looking for them in China.”
Most paleontologists believe that an asteroid struck the off the eastern coast of Mexico 65 million years ago, an event that pushed the already declining dinosaurs towards extinction. The paleontological data of that era is strikingly clear: the earth shows a distinct change in rock and soil structure along a line known as the K-T boundary, a line that splits the Cretaceous period from the Paleocene, a split between the time of dinosaurs and the rise of mammals.
But the world is a big place, attests Lucas. Even if the asteroid's impact sent up plumes of ash and soot, large creatures living on the opposite side of the globe possibly could have survived. Some dinosaurs may have loped on into the Paleocene era.
So the fight is not over whether dinosaurs survived; it's over location.
James Fasset, a paleontologist who holds an emeritus position at the U. S. Geological Survey and author of the initial study, believes that he has found bones of Paleocene dinosaurs in Ojo Alamo Sandstone of the San Juan Basin, a 4,600 square mile region that spans parts of Colorado and New Mexico. He supports the claim by a wealth of data, from pollen samples to the geochemistry of the bones, which were a collection of 34 hadrosaur bones.
“Dinosaurs surviving [would not be] a unique event,” says Fasset, referring to the fact that many animals did survive the event 65 million years ago. “But it's unexpected, because this is the first time it's been demonstrated, unequivocally I think.”
Lucas, however, does not see the data in the same way. Though he published a paper with Fasset in 2000 supporting the idea of Paleocene dinosaurs in the San Juan Basin, he has since revised his stance. He and a collection of colleagues wrote a critique article following the publication of Fasset's data stating that the bones had been reworked, a term that paleontologists use for fossils that have been moved from their original resting place rivers or other eroding forces.
“In the end, this issue is really simple,” Lucas says. “Does the data that [Fasset] is presenting convince you that there are Paleocene-aged dinosaurs in the San Juan Basin? And the answer from our point of view is that they don't.”
Lucas believes Fasset is missing two pieces of evidence that would absolutely show a bone is from the Paleocene era. First, a bone that shows no signs of reworking would have to be found in Paleocene rock. And second, next to that bone you would have to find an “unquestionably Paleocene” fossil, a species that only ever lived during the Paleocene. And while Fasset believes the pollen found with the hadrosaur bones fits the second requirement, Lucas is not as convinced. When he tried to repeat the result of that experiment, Lucas did not find the same pollen.
“So the bottom line is that [Fasset] doesn't have the smoking gun here,” says Lucas. “He doesn't have Paleocene pollen beneath a convincingly in-place dinosaur bone. He's [claiming] Paleocene pollen beneath a bone and we can't repeat the result.”
Fasset, however, remains steadfast. He wrote a rebuttal to Lucas's critique, and is hard at work gathering new data to support his claims.
“At this point, I feel absolutely 100% convinced that [the bones] in the Ojo Alamo are Paleocene,” he says. “But because there is skepticism, I'm trying to find other independent means to verify.”
In the end, both scientists have one thing in common: they both believe that it is possible that some dinosaurs survived the mass extinction. But irrefutably conclusive proof has yet to be found.
Comments
evidence for post k/t plants has been claimed by a scientist studing the patogoina region of south america, this is not as remarkable as it might seem. the source of the extinction might have not been world wide. cretaceous period plants might have survived this time line(k/t) by as much as 5million yrs. the
patogonia was isolated by the andes.
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