A US paleontologist is challenging one of the field’s greatest theories: the mass extinction of dinosaurs at the end of the Cretaceous period.
65 million years ago, a catastrophic event (or perhaps events) wiped out all large dinosaurs. This is a fairly well-established point of fact in the world of paleontology. Besides the ancestors of birds and crocodiles, which survived, it has never been shown that large dinosaurs lived through the event.
But is that really the truth? Jim Fassett, a paleontologist who holds an emeritus position at the U. S. Geological Survey, recently published a paper in Palaeontologia Electronica with evidence that points to a pocket of dinosaurs that somehow survived in remote parts New Mexico and Colorado for up to a half million years past the end of the Cretaceous period. If true, these dinosaurs would be the only ones that made it to the Paleocene Age.
The bones, found buried in Ojo Alamo Sandstone in the San Juan Basin, could hold some spectacular secrets. But in order to find them, Fassett must first face the considerable skepticism that has met his claim. "The great difficulty with this hypothesis - that these are the remains of dinosaurs that survived - is ruling out the possibility that the bones date from before the extinction,” he says. “After being killed and deposited in sands and muds, it is possible for bones to be exhumed by rivers and then incorporated into younger rocks." [EurekAlert]
Using sedimentary levels is a common way to date artifacts, but is not always completely accurate because of the influence of river waters. So the truth must be found in the bones. What Fassett discovered is that "the dinosaur bones from the Ojo Alamo Sandstone have distinctly different concentrations of rare earth metal elements to the bones in the underlying Cretaceous rocks [which] make it very unlikely that the post-extinction bones were exhumed from the underlying sediments." [EurekAlert] There is also the fact that 34 hadrosaur bones from one animal were found clumped together—if a river had swept through the area and re-deposited the bones, they would not have been found in such close proximity to one another.
Despite the evidence, there are, of course, still skeptics. However, David Polly, an editor of Palaeontologia Electronica , stated "we already know that flying theropod dinosaurs (more generally referred to as birds) and crocodiles survived, so the possibility of pockets of survivors of other types of dinosaur is not quite as farfetched as it might sound. Finding conclusive evidence, however, is a difficult matter when the crime scene is 65 million years old.” [EurkeAlert]
You can read the original journal article in its entirety here.
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Comments
California company recently announces cloning of 437 extinct dinos! mydinos.com, haha!
"Besides the ancestors of birds and crocodiles, which survived, nothing lived through the event."
I think quite a lot else survived actually. e.g. the ancestors of modern plants, insects, bacteria, nematodes, mammals, etc., etc., etc.
your right plankton also survived
Steve, great point. I made that statement far too inclusive. Shall change it accordingly.
I read a few days ago that it wasn't the impact in the Gulf Of Mexico (they can't find evidence of one) and the death was caused by a supervolcano. I'm foggy here, but think it said it was in India. It through so much up into the atmosphere, it blocked out the sun.
If I can find it again, I'll get back on here.
Article for Grethen Bietz
This is an excellent example of why we typically don't see something unless we're looking for it. If we're told that dinos went extinct at the end Cretaceous, and we want to find bones, where are we going to look? Not in the Tertiary! Granted a lot of field work has been done in early Tertiary deposits around the globe and this is the first we're hearing of possibly in situ dinos. But, again, these things are easy to miss, especially if we're not looking for them. Best of luck to Dr. Fassett.
"If true, these dinosaurs would be the only ones that made it to the Paleocene Age."
Given that the start of paleocene was originally delineated by the mass extinction, this statement is somewhat ridiculous. Also, no one posits that all the dinosaurs died on the same day.
In reply to 'Carpety': I really don't think we have the technology for that, plus we'd need to find some way to actually give birth to them, and I don't think we have an animal with the size or genes of dinosaurs. Not criticizing, just wondering.
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