Peter Wellnhofer

Picked up at the Wyoming Dinosaur Center, which has the only Archaeopteryx specimen in the Western Hemisphere. Coffee table book combined with paleontological monograph; old pictures – lithographs, appropriately enough – of the Solnhofen quarries; paleogeographic reconstructions of the area in the Jurassic; detailed photographs and skeletal drawings of all the specimens; and discussion of the implications of the fossils.

The Solnhofen Limestone was apparently deposited in a shallow, tropical or semitropical lagoon. The bottom water became hypersaline and anoxic, leading to a number of sad little trails of various marine organisms ending the preserved organism itself, after it blundered into the lethal water. I’m a little puzzled; usually anoxic sediments are black due to accumulated carbon uneaten by organisms; but perhaps the combination of anoxia, hypersalinity, and low organic detritus input left the Solnhofen limestone a beautiful cream. There was land near the lagoons, but not too close; although there are plant fossils, they are just leaves and bits of branches – no trees or even large limbs – and land animals that show up appear to have been naturally mummified before being washed into the lagoon. While there are numerous – hundreds – of pterosaur fossils, there are only ten Archaeopteryx; the suggestion is the pterosaurs lived nearby while Archaeopteryx habitat was some distance away. None of the Archaeopteryx seem to be naturally mummified, but all ten are immature; the suggested explanation is young birds caught in storms, forced down into the water, drowned, and sunk.

Author Peter Wellnhofer is the world expert on Archaeopteryx lithographica, and it shows in his detailed analysis of the specimens. Along the way, he discusses a number of common questions:

(1) What was it life habit? It seems to have preyed on insects or small animals. None of the specimens show any stomach contents. The teeth are unsuitable for fish-eating; the jaws have sliding joints that would have allowed a larger gape than a simple hinge.
(2) What was its metabolism like? Modern birds have an extremely efficient respiratory system, with multiple air sacs communicating with the lungs and into the hollow bones. Archaeopteryx had some openings into its bones, but not as many as a modern bird.
(3) Was it a tree-dweller? Probably not, or only opportunistically. The foot structure doesn’t preclude perching but isn’t that well suited for it either. The claws on the wings might have aided in climbing but reconstructions suggest they were normally covered with plumage.
(4) Could it fly, or was it just a “directed glider”? The calculated wing area is well within the range of extant flying birds; however, the skeletal structure imposed some limitations. In particular, Archaeopteryx probably couldn’t take off without a long run (the supracoracoideus muscle in modern birds is important for the upstroke in takeoff; in Archaeopteryx this muscles was a wing depressor rather than a wing elevator) and would not have been very maneuverable (the “wrist” structure hadn’t developed to the level seen in extant birds). Landings might have been tricky as well; the long bony tail wasn’t as maneuverable for braking as the tail feathers in modern birds. Wellnhofer concludes that Archaeopteryx could fly, but only fast, without any of the slow-speed maneuvers of modern birds.

Wellnhofer doesn’t dignify the various creationist arguments about Archaeopteryx by addressing them, nor does he comment on the supposed Triassic bird Protoavis; however, he does devote a paragraph to dismissing the unfortunate claim by Sir Fred Hoyle that the British Museum Archaeopteryx specimen is a forgery.

There’s a discussion of the Haarlem, Netherlands specimen and zoological nomenclature. This was discovered in 1855, thought to be a pterosaur, and given the name Pterodactylus crassipes. In 1970 the American paleontologist John Ostrom visited the museum; on examining it he was amazed to see that under glancing light faint feature impressions were visible, and this was actually an Archaeopteryx. Since the specimen was found and named before the first Archaeopteryx (in 1861), under strict rules of zoological nomenclature the name Archaeopteryx lithographica should be suppressed in favor of Archaeopteryx crassipes. (A similar thing happened to Brontosaurus). However, there’s a provision in the nomenclature code for the retention of old and familiar names, and Archaeopteryx remains lithographica.

Well done; extensive illustrations, numerous appropriate footnotes, extensive reference lists and bibliography. Expensive.… (mehr)