Hype, hype, hype

Update: The paper this post discusses is available online and is open access. It can be found here.

A new ScienceDaily piece reports on new molecular clock data that suggests modern birds have an "ancient origin" about 100 million years ago. My first thought upon reading the brief article was "This is news?" yet the details of what the paper actually says is going to be important in any discussion of the results.

I haven't read the actual paper yet, but article notes that the authors are referring to the diversification of modern birds, or Neornithes (see comments below, & thank you to Mickey and Neil). This distinction, which I feel will be missed by many lay readers and others not familiar with the state of the issue (hell, I slipped up myself) is important because there are at least three birds in the fossil record known to be more than 100 million years old; Archaeopteryx (about 155-150 million years old) from the Late Jurassic of what is now Germany, Confuciusornis from the Early Cretaceous (120 million years old) of what is now China, and the Early Cretaceous Changchengornis (125 million years old), also from what is currently China. The North American toothed birds Ichthyornis (about 93-75 million years old) and Hesperornis (about 89-65 million years old) are a bit younger, but still close enough to gain a mention here. Likewise, there already seem to be a number of neornith birds from the Cretaceous, although many of these are fragmentary and controversial; Vegavis iaai, Novacaesareala hungerfordi, Lonchodytes estesi, Torotix clemensi, Teviornis gobiensis, Palintropus retusus, Ceramornis major, and Gallornis straeleni.

The problem with neornith fossils is that specimens are often fragmentary, but it seems that by the Late Cretaceous there were already a number of modern birds present (hence I don't think the ScienceDaily article is correct in stating that paleontologists are inferring that the evolution and radiation of modern birds happened after the end-Cretaceous extinction). The disparity between what the fossil record suggests and what the molecular clock data suggests do not seem to be in that much of a conflict, then, although discoveries of earlier modern birds could help fill in some open slots and better calibrate molecular studies. Still, molecular clock methods are still controversial and I imagine that the new paper is going to spark debates similar to those about the mammalian "supertree" that came out last year (see the link in this previous post for evidence that the mammalian supertree was off).

Presently there is still a lot of distrust between paleontologists and researchers who try to figure out emergence dates for various clades using molecular clock methods. Admittedly, I interpreted the article somewhat incorrectly the first time I read it, mostly because I'm still skeptical of the accuracy molecular clock methods and I was not aware of the current state of the fossil evidence as far as Cretaceous modern birds are concerned. I'll have to take a look at what the paper says and what the authors say about the fossil evidence (if anything), but I do have to say that I think the ScienceDirect piece was a bit overhyped to try and make the new paper seem more important. Collaborations between paleontologists and molecular biologists/geneticists, at least in some instances, have led to greater resolution in some areas (i.e. the placement of whales within the artiodactyla), so I'll definitely be interested to see whether the hypothesis of a 100 million year old emergence for modern birds is supported or refuted by future papers.