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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 Slyne on 2/1/2010 3:30:34 PM , Rating: 2
Most evolutions have no direct effects, that is they don't help an individual thrive nor do they make its life more difficult. However many descendants continue that lineage. Each individual at birth then inherits myriads of features that make it unique. At some point a feature or a combination of features suddenly make an individual more likely to feed, breed, adapt to the environment, etc... Even then it may not pay off, because say a predator ate the particular individual in the nest, or some other inherited feature made the individual less likely to thrive, or another individual concurrently came with an even better feature, etc

But if that individual manages to breed, and its uniqueness gives it a 1% chance to better survive than other individuals of its species, then it becomes a number game until its kind takes over the species, at least locally. For instance, 1,000 generations later that individual will have more than 20,000 times as many descendants than any 'regular' member of its species; and since most species breed every year, 1,000 generations may not take that long in perspective.

As for your example, if lighter bones were not detrimental to the survival of the individuals who had them, and if webbed fingers were not detrimental either then eventually came an individual with both, endowed with primitive flight (or glide as was suggested by another poster), and that gave it a heck of an advantage over the other members of the species.


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