Dinosaurs Stretched, Shrunk and Twisted Into Birds
Size matters, thought paleontologists envisioning the evolution of birds from dinosaurs. The old story was that dinosaurs shrunk as their arms were becoming wings. That view has been challenged by a new fossil reported in Science.1 Alan H. Turner (American Museum of Natural History) and four others reported a “basal dromeosaurid” that was small long before it ever dreamed of flying. Furthermore, three related lineages subsequently grew to monsters up to two orders of magnitude larger. “Thus, miniaturization preceded the avialan node and the origin of flight,” they concluded, “and as a result, hypotheses relating ontogenetic or metabolic controls on miniaturization to flight origin in theropods must be equally capable of explaining the size reduction within ancestral paravians and the iterative trends of size increase in deinonychosaurs” which include the presumably fearsome Velociraptor and Utahraptor.
The press release at North Carolina State University, where co-author Julia Clarke is an assistant professor of paleontology, focused on the puzzles this find represents. “Height or flight?” the title asks. “Fossil Answers Some Questions About Evolution of Flight in Dinosaurs, Raises Others.”
Paleontologists have long theorized that miniaturization was one of the last stages in the long series of changes required in order for dinosaurs to make the evolutionary “leap” to take flight and so become what we call birds. New evidence from a tiny Mongolian dinosaur, however, may leave some current theories about the evolution of flight up in the air.
The small, 28-inch species, Mahakala omnogovae, was classified as a dromeosaur – a cousin of Velociraptor. Discerned to be a young adult, it did not fit the picture of miniaturization occurring late on the trail to birds. The press release was honest about the problems:
If miniaturization of dinosaurs occurred well before the origin of flight, then this raises other questions about the ways that paleontologists have traditionally explained trends in the early history of birds.
“We had closely linked smaller size in dinosaurs including birds to flight, changes in growth strategy and metabolism: They got progressively smaller, grew faster, and flew,” Clarke adds. “Now we see that small size occurs well before many other innovations in locomotion and growth strategy. It forces us to look at the ways we were explaining trends within this part of Dinosauria, and to question our previous assumptions about causal factors in, and timing of, the acquisition of attributes seen in living birds.”
The touch of humility in this quotation stood in stark contrast to the version in National Geographic News. Titled, “New ‘Mini’ Dinosaur a Step in Bird Evolution Path,” the report by Kevin Holden Platt was mostly confident that this fossil helps explain how dinosaurs took flight. “An 80-million-year-old fossil recently uncovered in the Gobi desert could be a key piece of the evolutionary puzzle of how massive dinosaurs gave rise to today’s comparatively tiny birds,” he began. He quoted a paleontologist who claimed that “the new find fits perfectly into the theory that dinos evolved into birds.” Only in the body of the article, on page two, did the problems surface:
Today consensus is building among paleontologists that dinosaurs and birds are linked.
But the experts disagree over how that evolutionary twist helped ancient birds escape being wiped out with the rest of the dinosaurs 65 million years ago.
“Paleontologists really don’t know the answer to that. Why some animals survive mass extinctions while others don’t is one of the most difficult questions in paleontology,” lead study author Turner said.
“Flying doesn’t seem to have hurt birds, yet pterosaurs—which are not dinosaurs—flew but went extinct.”
Other than that, the article was confident that Mahakala was a prize specimen for the evolution-of-flight display cases. Of special note was Platt’s insistence that the bird had feathers. Finding imaginary feathers on dinosaurs seems to be a habit at National Geographic (see 06/13/2007, 02/08/2006, 09/27/2000). The NCSU press release said nothing about feathers. The original paper only said that another species, Jinfengopteryx, classified as a troodontid, had feathers. There has been controversy, however, about this classification. Originally it was placed with Archaeopteryx, a true feathered flyer. Some paleontologists later felt it has more in common with troodontids, but the classification remains questionable. The artist reconstruction on Wikipedia looks like a roadrunner with long tail feathers. Even the decision to place the troodonts with dromeosaurs has had a checkered past; in many respects, its members seem to have more in common with Archaeopteryx and birds. Only Jinfengopteryx had clear feather impressions.
Nevertheless, Kevin Platt gushed about feathers in his article. Some of this may have been due to the lead author’s opinions on the matter. “The fossils indicate that the new species was not only feathered but also likely had winglike forelimbs and hind limbs, Turner said.” Platt quoted only believers, like Xu Xing and Mark Norell, to confirm the suspicion that Mahakala had feathers. He even stated flatly that the specimen “measures just 27.5 inches (70 centimeters) from its head to the tip of its feathered tail.” The artist reconstruction in the article showed the specimen well endowed with wing feathers.
No other source checked said that Mahakala had feathers. Turner and National Geographic, however, insisting that it was a dromeosaur, had their feathers a-flutter. They seemed excited that this little bird-like fossil might be related to the terrors of Jurassic Park. Turner confidently put imaginary feathers on those monsters, too, saying, “The Velociraptor would be completely covered in feathers.” No Velociraptor fossil has ever been found with feathers.2
1Alan H. Turner, Diego Pol, Julia A. Clarke, Gregory M. Erickson and Mark A. Norell, “A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight,” Science 7 September 2007: Vol. 317. no. 5843, pp. 1378-1381, DOI: 10.1126/science.1144066.
2The Wikipedia entry on Velociraptor, biased in favor of the dinosaur-to-bird theory, only claims that earlier dromeosaurs had feathers (referencing Xu Xing’s classification of Microraptor with dromeosaurs). Then it makes the following inference and admission: “In light of the fact that the ancestors of Velociraptor were feathered and possibly capable of flight, it is most likely that Velociraptor bore feathers too, since even flightless birds today retain most of their feathers. While there is as yet no direct fossil evidence to confirm that Velociraptor had feathers, there is no reason to suspect it of being an exception.”
The twists and leaps that evolutionists make to keep their belief intact is an affront to scientific integrity. Here, an assumption that dinosaurs shrank on their way to flight has been shown wrong. At least the NCSU press release showed a little bit of honesty that “we have a problem here” but that was undone by Turner and Platt’s shameless boasting about things they don’t know. The original paper’s chart of dinosaur phylogeny is a jumbled mess, with feathers here and there and sizes varying all over the place. Deeper investigation shows a good deal of doubt and controversy about each group’s place in the imaginary tree. The believers in the consensus keep striving to marginalize the critics.
Once again, there is no simple, straight line from the alleged ancestor to the alleged descendent (cf. 09/01/2007). The assumption of evolution, however, never gets doubted. Evolution may have to stretch, squish and twist to keep the observations from falsifying the theory, but Darwin Gumby always comes out the hero. We are watching one of the worst cases of belief trumping evidence in the history of science. When all the fossils get sorted out, and all the facts come to light, certain people may have a lot of egg on their faces.