Don’t Hate on ArchaeopteryxPosted: August 1, 2011
Archaeopteryx Not the First Bird (Duh)…
Xu X, You H, Du K Han F (2011) An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475, 465-470.
This paper made a big splash this week because many news organizations took it and ran with it. Some of the headlines read “Fossil May Evict Archaeopteryx From Avian Family Tree” and “Archaeopteryx Knocked From Roost as Original Bird“. Archaeopteryx is a famous fossil that for about 150 years now has been referred to in popular culture as “the first bird”, and often used as an example of an evolutionary transitional form demonstrating how birds evolved from reptiles. It’s not surprising that creationists at best misunderstood and at worst distorted the findings from this paper because they hope to finally vanquish a long-hated opponent in their quest to delegitimatize evolutionary theory. What they are not reporting on is that there is no problem. Phylogenetic systematics, which is the biological sub-field concerned with reconstructing the branching pattern of species diversification over time, is constantly reworking evolutionary trees when new data comes in. The take-home message from this week’s paper in Nature is that other fossils that have been found in the past hundred years or so have illuminated the fact that Archaeopteryx was not the ACTUAL ANCESTOR of every bird that appeared after it. Rather, it represents more of a cousin of the first birds.
Paleontologists already knew this, but exciting new fossil discoveries from China of bird-like dinosaurs, especially one new to science named Xiaotingia, have demonstrated that early on in bird evolution there were many traits we now attribute to birds that can be found in many of these bird-like dinos that are so close to that bird ancestor (ie feathers, avian respiratory systems, endothermy). We are not ever going to find the one true bird ancestor, however we are now getting enough fossils that allow us to more accurately imagine what it may have looked like.
Which is why I think this paper is cool, and not because it BLASTS ARCHAEOPTERYX FROM ITS POST AS THE FIRST BIRD, as many sensational news outlets would prefer to report. Archaeopteryx turns out to be closer to some other types of bird-like dinosaurs than to other types of extinct creatures that eventually gave rise to the lineage leading to modern birds. Again, this is not completely surprising because Archaeopteryx has many traits that make it more dino-like than bird like. Without getting into detailed morphological analyses (that is out of my area of expertise), these traits include teeth, lack of a beak, and a bony tail.
Remember, evolution looks like a bush, not a ladder. It’s too bad that while systematics (and the tree-type thinking that accompanies it) is an essential field in biology, it is probably the least understood by the general public. I hope to be able to help change that someday, as an educator and as a scientist.
PS: PZ Meyers is going ape on the creationists over their exploitation of this article. Keep it up, PZ!