A fossil touted since the time of Charles Darwin as the "missing link" between dinosaurs and birds is likely just a dinosaur, scientists have admitted in a new report in the journal Nature..
The proposal to reclassify the specimen Archaeopteryx, which has been presented since its discovery in 1861 as a key transitional link, highlights the shifting sands on which much of evolutionary theory is based, according to one expert in the field.
David Menton of Answers in Genesis has a Ph.D. in cell biology from Brown University, taught anatomy at Washington University School of Medicine, lectured in anatomy, was a consulting editor for "Stedman's Medical Dictionary" and has been profiled in "American Men and Women of Science – a Biographical Directory of Today's Leaders in Physical, Biological and Related Sciences."
He told WND the developments reported by Nature directly undercut the assumptions of Darwinian evolutionary theory.
"Just how many papers have we had talking about this being a bird?" he asked.
A summary of the scientific paper in naturenews explains that Xing Xu, a paleontologist at the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, is suggesting Archaeopteryx is "not a bird at all."
The report says the latest discovery suggests the assumption that Archaeopteryx is "the evolutionary link between the two [birds and dinosaurs]" may need reconsideration.
The discovery, called Xiaotingia zhengi, was found in western Liaoning, China, in rocks dating to the Jurassic time frame, an assumed 161 million to 145 million years ago.
This one, like others, the report said, has feather impressions in the rock, but it also has claws on its forelimbs and sharp teeth.
"Xu reports that it also has extremely long middle and last finger bones and a wishbone with an L-shaped cross-section at one end. These characteristics, Xu argues, identity Xiaotingia as very closely related to Archaeopteryx and another feathery relative, Anchiornis."
However, Menton told WND that such assumptions are built on unstable foundations, since the report author himself, Xu, wrote, "It should be noted that our philogenetic hypothesis is only weakly supported by the available data."
Further, Menton noted the "specimen" was purchased and not found in situ, raising an entire line of questions about authenticity, provenance and origin.
Xu's conclusion after looking at the specimen was that such creatures resemble more closely dinosaurs than early birds, "and so belong in the dinosaur group Deinonychosauria rather than in the bird group, Avialae."
But what about the century-plus that Archaeopteryx was considered "the ideal 'missing link' with which to demonstrate evolution from non-avian dinosaurs to birds"?
According to the report, Xu explained, "I think Archaeopteryx's placement was the result of both history and relatively poor sampling at the dinosaur-bird transition..."
...The AP commented on the Nature report that the effect of Xu's writing could be to move Archaeopteryx from the "bird" branch of evolutionary teachings to another branch containing "birdlike dinosaurs."
Prominent professor Lawrence Witmer at Ohio University told AP that any reclassifications wouldn't matter much, but it might push scientists to reevaluate evolution of birds themselves.
"Archaeopteryx has been the touchstone," he said. But now, that "centerpiece" may not even be part of the "lineage."
Oliver Knevitt on the Science2.0 blog tried to make the problem clear: "Birds are a group of therapod dinosaurs, and as such are the only group of dinosaurs still to roam the Earth. … [But] at what point does a maniraptoran dinosaur become a bird?
"Back in the day, when we had a lot less fossils, it was a lot easier. Birds have feathers and wishbones. Simple. But slowly, we've found more and more examples of what were thought were bird-only [characteristics] turning up in theropod dinosaurs – so much so, that what we now think of as unique to birds is very different."
He continued, "I will say this, though: don't expect this to be the last you've heard of this. I think it is probably quite likely that there may be another reclassification, and Archaeopteryx may find itself being reclassified as a bird again."
Friday, July 29, 2011
More debate over the classification of Archaeopteryx
Remember, evolution is proven science! As reported by Bob Unruh of WorldNet Daily, July 28, 2011 (links in original):