Wednesday, October 9, 2013

Fossils Fail to Transition from Dinosaur Legs to Bird Wings

by Dr. Elizabeth Mitchell

ScienceDaily: How Birds Got Their Wings: Fossil Data Show Scaling of Limbs Altered as Birds Originated from Dinosaurs

How did birds get their wings? This “classic major evolutionary transition” fails to take flight in the fossil record.

Evolutionists maintain that birds evolved from dinosaurs but debate just how the transition happened. They are certain it did, of course, because birds exist and, in their view, had to evolve from something. Most evolutionists have maintained that this “classic major evolutionary transition”1 began with the gradual evolution of longer forelimbs among birds’ ancestral dinosaurs. However, careful analysis of the fossil record by McGill University paleontologist Hans Larsson and graduate student Alexander Dececchi, published in the journal Evolution, reveals that there is no such transition evident in the fossil record.

Archaeopteryx, considered an early “basal” bird and a transitional species
between dinosaurs and birds, like other birds and even some genuinely
feathered creaturessuch as the four-winged Microraptor, have
proportionally longer forelimbs and shorterhindlimbs
than their supposed dinosaur ancestors. The researchers  found
no trend among dinosaurs to account for this apparent
abrupt change in body proportions.
Image: H. Raab through
“Our findings suggest that birds underwent an abrupt change in their developmental mechanisms, such that their forelimbs and hind limbs became subject to different length controls,” says Larsson.1

Abrupt Appearance


Larsson and Dececchi set out to determine from the fossil record when and how dinosaur forelimbs evolved into wings. Instead of finding a gradual lengthening, they found that when proportionate changes associated with different body sizes are factored out, there really is no such trend. The longer forelimbs, shorter hindlimbs, and long metatarsals (foot bones that are so long in birds they look like legs) appear abruptly in the fossil record. The skeletal characteristics of birds, in other words, start when birds start. They have no gradually transitioning antecedents in the rocks.

“This decoupling may be fundamental to the success of birds, the most diverse class of land vertebrates on Earth today. The origin of birds and powered flight is a classic major evolutionary transition,” says Dececchi. “Our findings suggest that the limb lengths of birds had to be dissociated from general body size before they could radiate so successfully. It may be that this fact is what allowed them to become more than just another lineage of maniraptorans [dinosaurs presumed ancestral to birds] and led them to expand to the wide range of limb shapes and sizes present in today's birds.” He adds, “Knowing where birds came from, and how they got to where they are now, is crucial for understanding how the modern world came to look the way it is.”

Evolutionists compare the size, shape, and proportions of body parts in order to track the really big jumps in vertebrate evolution—like fish evolving legs and walking out onto land, mammals de-evolving legs and becoming whales, and of course dinosaurs evolving wings and taking to the air as birds. “Interlimb length ratios are widely used,” the authors write, “to derive evolutionary scenarios.”1

Extrapolating from Nothing


Having “derived evolutionary scenarios,” evolutionists then must explain how these leap...CONTINUE READING