Archaeopteryx must be one of the most famous fossil animals of all times, even though only seven specimens are known to exist. All come from a site in Bavaria, and are about 150 million years old. They are beautifully preserved and show a bird-like animal with feathered wings, toothed reptilian jaws, and a long bony tail. It is a true "missing link", but what exactly is it a link between? Enormous controversy has surrounded this question, and some commentators have even claimed that the feathers are faked. Shipman discusses this suggestion at some length but dismisses it.
Ever since its discovery in the last century Archaeopteryx has been regarded as a central piece of evidence for the evolutionary origin of birds. One popular view today is in line with Thomas Huxley's opinion: birds are descended from dinosaurs. An alternative view is that birds descended, not from dinosaurs, but from some other unknown reptilian ancestor. Another argument concerns the flying capacity of Archaeopteryx. Could it fly at all, and if so, how well? Could it, for example, take off from level ground or did it have to climb a tree first in order to jump off? Did it flap its wings or was it merely a glider? Shipman discusses all these questions at length, and in passing also writes about the evolution of flight in insects and pterosaurs. I found the discussion of pterosaurs particularly interesting. They varied in size from a chicken to a small aeroplane. The conventional illustrations in books, depicting them as batlike, with wing membranes extending to their legs and tails, are almost certainly wrong; there is a good deal of evidence to show that they had quite narrow stiffened wings that left their legs free for manoeuvre on the ground.
But back to Archaeopteryx. Could it fly, and what does it tell us about the evolution of birds? No final answers are available for these questions, but Shipman reaches some moderately confident conclusions. Dinosaurs were more like birds than like reptiles: they built complex nests, nested in colonies, and hatched dependent babies which they cared for and fed for prolonged periods. They may also have been warm-blooded. For these and other reasons, they seem plausible ancestors for birds and Archaeopteryx has many dinosaur-like features. As for flight, Archaeopteryx could not have been a strong flier by modern avian standards and could not have competed with pterosaurs in their own environment (probably over the sea); however it's likely that it could take off from level ground and could flap its wings effectively enough to allow it to fly in the wooded areas where it probably lived.
This is a fascinating and well-written book. Anyone interested in evolution would enjoy reading it.