The week before last was Michelle’s spring break, so I took a day off to take her down to the Mesa Southwest Museum (AKA Arizona Museum of Natural History) to see the traveling “Feathered Dinosaurs” exhibit.
There is a province in Northeastern China called Liaoning, where, 120-odd million years ago a lake and a volcano combined to preserve an abundance of unique and exquisitely preserved fossils. Probably the most important finds coming out of the Liaoning fossil beds are… well, let’s call them “feathered dinosaurs”, since that’s what the exhibit is called.
Ever since the discovery of Archaeopteryx in the 19th century, it’s been clear that birds evolved from reptiles. Specimens have been few and far between, but in the later part of the 20th century, dromeosaurs were discovered.
No, that’s not a good place to start, let’s try again. A long time ago there were Archosaurs, the ancient reptiles that came before dinosaurs. Archosaurs led to dinosaurs, marine reptiles, flying reptiles and crocodilians amongst others.
Dinosaurs broke into two major groups – bird hipped and lizard-hipped. Bird-hipped dinosaurs are somewhat unfortunately named as they have no connection to birds and have no further part in our story, but are represented by familiar dinosaurs such as Iguanodon, stegosaurus and triceratops.
The lizard-hipped dinosaurs further branched into theropods and sauropods. The sauropods being the gigantic diplodocus and other long-necked forms. The theropods are the great two-legged meat eaters – the Tyrannosaurs and such.
Then they discovered Dromeosaurs. Which are classified as theropods, although they are generally smaller and have some unique characteristics, such as long arms, and often a wicked retractable killer claw on the hind feet. Think Velociraptor from Jurassic Park, and you’ve conjured up the image of a dromeosaur.
Perhaps you noticed between Jurassic Park and Jurassic Park III, the ‘raptors suddenly gained feathers.
For most of the 20th century, Archaeopteryx was thought to be a parallel line of development, alongside the dinosaurs – just as marine reptiles and flying reptiles were. The problem was, not enough evidence to say where they branched from.
When dromeosaurs were discovered in the 1960′s, it became obvious that significant physiological similarities existed between them and birds. The branching point where birds began to separate from reptiles was found. Or was it?
The case for the dromeosaur/bird relationship has been strengthening steadily over the years, and increasing number of dromeosaurs have now been identified (or extrapolated) as having feathers.
Now, the researchers who put together the “Feathered Dinosaur” exhibit, based on the amazing finds in Lioaning have arrived at a new conclusion and turned things on their head: Dromeosaurs aren’t theropod dinosaurs on the way to becoming birds at all. They’re not dinosaurs at all. They’re flightless birds, like ostriches. These are creatures whose ancestors developed true feather and wing flight, but who, through some form of evolutionary selection pressure, became land-dwelling creatures, similar in appearance to theropods, but not related any closer than the Archosaurs.
I’ve read the (rather sparse) material associated with the exhibit and it makes a logical case. No evidence is presented to counter the hypothesis, and I don’t know what the reaction has been in the paleontological community has been.
What I do know is that, if this were such an obvious slam dunk of an hypothesis, I would imagine I would have to have heard more about it than I have. Has consensus been achieved this quickly? Or is this hotly contested? I can only imagine the latter. That’s the way science works, in fact, that’s probably how science works best. If there’s any lesson to be learned in science for the general public, it is that science is a self-correcting system that arrives at conclusions via evidence, multiple independent verifications and a lot of academic debate.
So, why am I bothered?
I’m bothered because the museum was rather full of kids on field trips and they were stocked up on docents, and they were telling everyone about this theory as if it were completely proven. The materials accompanying the exhibits were not much less certain, but the book that can be purchased separately does at least pay some lip service to the notion of academic debate on these findings. I don’t blame the authors, exactly, for they are putting forward their case, and doing a convincing job – at least to this layman, but at the same time, as far as I can tell, dromeosaurs are still considered theropod dinosaurs – for now.
Anyway, despite that, it is an amazing exhibit! These are some of the most exquisite fossils ever found. The preservation is such that you can see intricate details on the wings of bugs. It’s astounding.
How sad that these fossil beds are stuck in China. The local farmers can make a comparative fortune finding and smuggling out fossils. The fields aren’t well guarded and, well, let’s be brutally honest: Chinese officials are corrupt to the core. A payoff here and there and who knows how many incredible finds are in the hands of some private collector?
No pictures are allowed in the exhibit (and armed guards will stop you if you try*) and no pictures are available for purchase, although the companion book, Feathered Dinosaurs by Stephen A Czerkas and Sylvia J. Czerkas has photos of all the exhibits and the text of the placards, along with some additional material.
I strongly recommend anyone with an interest in paleontology to see this exhibit if you get the chance. For most people, it’s probably a once in a lifetime exhibit.
*Or is the purpose of the armed guards to stop political activists from unfurling “Free Tibet” banners?