Dinosaur Forces Rethink Of Flight's Evolution

gollum123 writes "The BBC reports that a small dinosaur with a long, slender snout and wing-like limbs is forcing a rethink on bird evolution." From the article: "The 90 million-year-old reptile, called Buitreraptor gonzalezorum, belongs to the same sickle-clawed group of dinosaurs as Velociraptor and feathered dinosaurs from China. It may provide tantalising evidence that powered flight evolved twice. One theory suggests the lineage of dinosaurs the new animal belonged to, the dromaeosaurs, originated in the Cretaceous Period (144 to 65 million years ago). But this discovery suggests their lineage can be traced further back in time, to the Jurassic (206 to 144 million years ago), experts say."

Comments

No you can't recover the DNA

[sam_handelman]

Since this comes up in every slashdot story on dinosaurs, no, Jurassic Park is not possible -

  Fossilization occurs when carbon atoms are exchanged for silicon. There is a very high energy barrier to this chemical event - so it happens extremely slowly, over millions of years.

  Nucleic acids, the building blocks of DNA, spontaneously decay (even in the absence of bacteria or degrading agents). The spontaneous decay of DNA is very slow by most standards - if kept under the proper conditions a DNA molecule can last for millennia. However, this spontaneous decay is a great deal faster than the exchange of carbon and silicon, especially when you consider that the carbon and silicon must exchange over the surface area of the sample (for example a bone several inches thick fossilizes very slowly from the outside in,) while the DNA is decaying continuously in the marrow. So, for a fossil millions of years old, even if you managed to recover something that looked like a nucleic acid base, it would be decayed to the point that the information content is completely gone.

Flight Evolved Twice?

[BarryHaworth]

From the posting:

It may provide tantalising evidence that powered flight evolved twice.

As I recall, powered flight has evolved independantly a number of times.

Insects

Birds

Pterosaurs

Bats

and if I not mistaken, fruit bats evolved flight separately to insect-eating "true" bats. That's at least four if not five times.

Re:Insect

[rolfwind]

I don't know if Hummingbird can be categorized as a different model of flight but:

http://oregonstate.edu/dept/ncs/newsarch/2005/Jun0 5/hummingbird.htm

They can hover, fly backwards/forwards, or even upsidedown.

From a Paleo Class

[Wyatt Earp]

In mammals and reptiles
Passive flight
a. Gliding
b. Parachuting;
Soaring
Powered flight

Bugs
The first animals to take to the air under control.
Carboniferous
The only flying creatures that evolved flapping flight without sacrificing limbs to form the wings.

Parachuting can evolve in animals with rather low metabolic rates.
It does not require the high metabolic rate of birds and bats, which have powered flight.
Late Permian reptile Coelurosauravus
Bones jointed for folding

No gliding lepidosaur is known from the fossil record after the Triassic, so the living lizard Draco which also uses elongated ribs to support an airfoil, must represent yet another independent evolution of gliding

Re:Not Flight, Intelligent Falling

[Bob9113]

Flamebait?!? Informative?!? Correcting my definition of "Theory"?!? Wow. I am astonished. OK, I know 99% of you got it, but for that "special" 1%, umm, it's a joke. Laugh. If you can't laugh at Intelligent Falling, you're taking it waaaaaay too seriously.

And if you're actually serious about the flamebait mod, and you're now thinking, "but it is serious, ID as scientific theory is a serious subject," you're wrong. It is not a scientific theory. I'm not saying it isn't true(*) so don't get your panties in a bunch. I'm just saying it is not science. Science is the search for natural explanations to non-intuitive phenomena. Scientific theories make predictions that are disprovable(**). ID is a supernatural explanation to a non-intuitive phenomena which does not make predictions and is not disprovable. As such, ID is philosophy of religion, or mysticism, or faith, or whatever term you feel is appropriate for the study of supernatural explanations to non-intuitive phenomena. Not a better field, not a worse field, not more true, not less true, just a different field of study than science.

So get over it. Laugh. Or are you afraid that the shared behaviour of laughing will betray your common ancestry with the great apes? Yes, ferchrissakes, that's a joke too.

Sorry about the "ferchrissakes" thing - I didn't mean to blaspheme. The editors of that paragraph have been sacked.

* Typically supernatural explanations are inherently not disprovable, and this is the case with ID. Any scientist worth his salt will not say that something is false if it can't be disproven. Listen closely next time, you'll not hear a serious scientist say "ID is not true." The scientists aren't trying to kill God, they're just working in a different field than philosophy of religion.

** For a great example of hardcore science-like research that is not science, check out game theory. It is a fascinating area of economic research, but since it can only be used to analyze and not predict, it is not science. There's a very good article on the topic here.

Re:Bird/Dinosaur

[Conanymous Award]

If birds came from dinosaurs birds should have evolved at the end of the Cretaceous not at the begining of the Triassic as the earliest bird accestors seem to show up.

Not at all. Birds, capable of real powered flight, are known from lower Cretaceous already (even upper Jurassic, if you count Archaeopteryx, which might infact come from a relic island population). Check out what has been found and is still being found from Liaoning, China. I study vertebrate paleontology and I'm not aware of any earlier bird-like creatures than middle or upper Jurassic. Can you give a reference? Longisquama might have had feathers (many paleontologists don't agree), but otherwise it's not very bird-like. Feathers might even have been a trait that many reptiles of certain kind had in those times.

The evidence for birds evolving from dinosaurs (and actually being dinosaurs) is nowadays overwhelming. The anatomical similarities between birds and maniraptoran dinosaurs are as obvious as those of apes and humans. Genera like Buitreraptor (a dromaeosaur) are actually very strong candidates of being secondarily flightless creatures (meaning, their ancestors had the ability to fly but reverted to flightlessness). Also, this new find also makes it clear that an earlier find, Rahonavis from Madagascar, is actually a dromaeosaur, and Rahonavis is generally considered having been capable of flight. Thus, we have a flying dromaeosaur! These are fantastic finds, and our picture of the evolution of birds becomes clearer by every one of them. And it is a very controversial field of study, we are probably still in for quite many suprises in near future. But that's what makes all of this so interesting.

Re:That begs the question ....

[drafalski]

Actually, it raises the question. Begging the question is a formal logic term that does not mean what most people seem to think.

Text from the link:

An argument that improperly assumes as true the very point the speaker is trying to argue for is said in formal logic to "beg the question." Here is an example of a question-begging argument: "This painting is trash because it is obviously worthless." The speaker is simply asserting the worthlessness of the work, not presenting any evidence to demonstrate that this is in fact the case. Since we never use "begs" with this odd meaning ("to improperly take for granted") in any other phrase, many people mistakenly suppose the phrase implies something quite different: that the argument demands that a question about it be asked--raises the question. If you're not comfortable with formal terms of logic, it's best to stay away from this phrase, or risk embarrassing yourself.