I recently picked up the March/April issue of a new magazine, Science Illustrated which is sort of like Discover Magazine-lite. Lots of pretty pictures (as the name suggests) but the actual information content is somewhat limited and in some cases it is more than limited, it is simply wrong.
For example while flipping through this issue I ran across a little two paragraph editorial piece on a small (non-avian) dinosaur fossil known as Sinosauropteryx: “Researchers Pluck “Feathered Dinosaur” Theory”.
A new analysis of fossils raises doubts about when feather first emerged. Previously, researchers believed that Sinosauropteryx, a turkey-sized beast that lived about 140 million years ago, was clad in ‘protofeathers’ that had evolved to keep it warm.
South African researchers have reexamined the fossil and now posit that the characteristic marks on the skin are not feather remains, but are instead collagen fibers. (Collagen is a protein found in connective tissue.) If true, this means that dinosaurs didn’t develop feathers as early as previously thought, and that birds evolved from a later group of dinosaurs.
The first problem is that this isn’t exactly new. The most recent place I can find (via a web search) a reference to someone from South Africa publishing on this in the scientific literature is from an article in the Proceedings of the Royal Society B from last year:
Theagarten Lingham-Soliar, Alan Feduccia, Xiaolin Wang (2007) “A new Chinese specimen indicates that ‘protofeathers’ in the Early Cretaceous theropod dinosaur Sinosauropteryx are degraded collagen fibres”, Proceedings of the Royal Society B: Biological Sciences, 274(1620):1823-1829
But it wasn’t even a new suggestion then. I heard this being argued 10 years ago, not long after Sinosauropteryx was discovered, by some in the anti-dino/bird crowd at the third DinoFest International Symposium in Philadelphia (1998). Nor is the idea that the ‘protofeathers’ on the Sinosauropteryx fossils are merely collagen fibbers widely accepted by other paleontologists.
The second problem is the conclusion that the S.I. editorial comes to. Because even if the collagen fiber hypothesis was accepted, it doesn’t change the fact that there are numerous other dinosaur fossils from the same area of China that Sinosauropteryx comes from which show clear impressions of unquestionable feathers.
These other fossils date from the early Cretaceous (as does Sinosauropteryx), whereas the oldest known ‘bird’ fossil, Archaeopteryx, dates from late Jurassic. So regardless of what the skin of Sinosauropteryx was covered with, the ancestor of birds is to be found among dinosaurs older than Archaeopteryx.
While many of the fossils from China are morphological intermediates between dinosaurs and birds they are not their actual ancestors. They are cousins to the actual ancestors who lived earlier, likely in the early or mid-Jurassic period.
So Science Illustrated does have lots of nice pictures (can’t wait for the swimsuit edition) but they’re going to have to work a little harder on the accuracy of their information content.
Brian Switek over at Laelaps posted a more detailed look at the Proceedings article referenced above.
I highly recommend that anyone interested in the evolution of birds from dinosaurs check out Luis Chiappe’s excellent book on the subject: Glorified Dinosaurs: The origin and early evolution of birds.