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An artist's rendition of Haplocheirus sollers  (Source: Portia Sloan)

The skull of the beast shows similarities to its cousins, the ancestors of modern birds. However, the creature's lacks some of the bird-like features of later members of the family, showing that the features likely evolved in parallel in both birds and the related dinosaur group.  (Source: NSF.gov)
Newly discovered dinosaur shows that in evolution lightning can and does strike twice

A newly discovered dinosaur in the Alvarezsauridae group has revealed that bird-like features likely evolved twice, both in dinosaurs and in the ancestors to modern birds.  Previously, the group was thought to be ancestors of modern birds, rather than evolutionary cousins. 

Describes Jonah Choiniere from George Washington University in an interview with BBC News,  "Haplocheirus is a transitional fossil.  Previously we thought the Alvarezsauridae were primitive, flightless birds. This discovery shows they're not and that the similarities between them evolved in parallel."

Like birds, the group of dinosaurs has fused wrists and loosely assembled skull bones, leading many paleontologists to believe that they might be the ancestors of birds.  The beasts may also have had feathers, according to analysis in the late 90s and onward.

However, anatomical analysis of a 3-meter long nearly complete skeleton of a new species in the group indicates that the group likely diverged from the line of dinosaurs that evolved into birds, and that the bird-like features emerged in parallel, not in series.  The new skeleton was dubbed Haplocheirus sollers and was found in the China's Gobi desert.  The skeleton was noticed by a member of a team excavating in the orange mudstone beds in the Junggar Basin of the Xinjiang province.  The member saw the pelvis of the dinosaur sticking out of the ground -- and the rest of the skeleton was found soon after.

Professor Choiniere describes, the results of the subsequent analysis, stating, "The rest of the members of this group have really short forelimbs with huge muscle attachments, like body-builder arms. The fossil shows the first step in the evolution of this weird arm and claw."

The new dinosaur is thought to have lived 160 million years ago, making it the oldest member of the family found to date.  Birds and Alvarezsauridae likely split not long before the evolution of the new find, say researchers.  Both group s likely are descended from the bird-footed dinosaurs of the early Jurassic, which include such famous members as the T. Rex and Velociraptor.

The new find likely was primarily an insectivore (as evidenced by its small teeth).  Its small claws were quite agile and would have been ideal for digging, leading researchers to speculate it likely ate termites, which were plentiful in its era and locale.  However, that likely didn't stop the versatile reptile from trying different cuisine. Describes Professor Choiniere, "It may have had a very general diet, tackling smaller animals like lizards, very small mammals and very small crocodile relatives.  It was a lightly built animal and could run very quickly."

The new work was reported in the journal Science.

The truly fascinating thing about this find is that it fuels the theory that in evolution lightning can, and likely will strike twice -- similar designs can evolve in parallel out of a common need.  Thus much of the anatomy in science fiction -- such as teeth on the titular Alien or giant wings and feathers of the flying monsters of Avatar -- may be realistic.  If life is found on other planets similar to Earth, it may show striking similarities as our own planet's fossil record indicates.



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By foolsgambit11 on 2/1/2010 5:17:03 PM , Rating: 2
Darwin talked about this in the Origin of Species. He used several mammals with varying adaptations to show that there was an evolutionary advantage to a wide range of gliding/flight adaptations. For instance, take "flying" squirrels, who can glide between trees thanks to the extra skin between their arms and legs, which could gradually have grown to its present size, each enlargement giving the squirrel a greater and greater advantage. I think he had 3 or 4 animals in his list of gliders/flyers, ending with bats, which can fly in the fullest sense of the word. All of which combines to demonstrate that there is an evolutionary advantage for every step on the path to flight, since these animals currently survive and thrive in their individual habitats. For birds, I think he briefly mentions the possibility that the wings could originally have been a swimming adaptation, but I think he was probably off from a historical standpoint. Theoretically, it makes sense - start with a penguin, then go to something that "hops" along the surface of the water, barely getting airborne for a few seconds, to full flight. But I think historically, penguins lost the ability to fly, rather than being a precursor to it.

The most interesting thing about reading the Origin of Species is that all of the arguments used against speciation when he published are the same arguments used today. He addresses concerns about special capabilities like flight, the development of complex organs like the eye, the lack of modern intermediate forms between species, the lack of evidence in the fossil record, the development of instinct simultaneous with changes in form, &c, &c. While he didn't get everything right (we believe now), and much of his analysis was through analogy more than direct evidence, the principle he (and others) developed has continued to be our best scientific explanation for the origin of modern species for 150 years. And the principle is so simple - life always varies, and the most fit variations survive - while the results are so complex.


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