Saturday, December 31, 2005

Jurassic Park left out the Feathers

kw: book reviews, nonfiction, paleontology, palaeontology, dinosaurs, birds

I grew up reading Roy Chapman Andrews's books on finding dinosaur fossils in the Gobi Desert of Mongolia. Those books and similar "science adventure" books had at least as much to do as my mother's influence (she was a rockhound) with making me into a geologist.


After reading Unearthing the Dragon I find its author, Mark Morell, has assumed Andrew's mantle. Here is a lavishly illustrated (thanks to his collaborator, illustrator and photographer Mick Ellison) and well written account of the fossil find of the turn of the century: the discovery first by Chinese scientists and then in collaboration with international colleagues, that many dinosaurs were feathered, and that birds are dinosaurs.

The subtitle of the book is "The Great Feathered Dinosaur Discovery". Its second title, shown here, puts a nuance on the title, where the "Unearthing" ideogram has the connotation of revealing, and those for "Dragon" refer to a living, rather than mythological, being. The real dragon being revealed here is the land and multifaceted cultures of China.

A word as to how creatures are grouped into families. As well as I understand it, the current controversy in cladistics—grouping like things into a hierarchical classification system—is about the definition of a clade. When a clade is defined, does it include or exclude those clades that arose from its own members? For example, the Vertebrates might be a clade to one scientist, but not to another, because it is understood to include five major groups: fish, amphibians, reptiles, birds, and mammals, plus a few little critters like lanceolets that are hard to place.

I think most people have little trouble with this, or with the placing of Vertebrates and the many kinds of Invertebrates (clams, worms, insects, and many more) into the big, kingdom-size group Animals. Going smaller gets us into trouble. If the amphibians arose from one or more kinds of fish are they part of the Fish clade? More to the point, if birds arose from dinosaurs, are they dinosaurs? Dr. Norell has one heavy-duty chapter at the end, plus solid materials scattered throughout the book, that support his contention (with which I agree) that birds are dinosaurs. The main difference between a crow and some of the fossils from China are that the crow has no teeth but is better adapted to flying. Many of those fossil critters—even some that look less like birds—probably flew, also, but it is hard to prove just which ones could, and which could not.


One thing is sure, though. Nearly all the dinosaur fossils from Liaoning Province are feathered, wherever they are preserved well enough to show the feathers. This illustration, a bit enhanced compared to the book photo (p. 185), shows feathers with vanes just like modern bird feathers.

One thing has become abundantly clear. Feathers did not evolve to enable flight, but for insulation. Feathers provide better insulation than any kind of hairy pelt. Flight arose later, much later. Thus, the feathered dinosaurs must have been warm-blooded. Whether they were as stably so as modern birds and mammals is not known, but they would not need feathers if their metabolism was lizardlike.

Throughout the book, the author regales us with anecdotes of his and Mick's adventures in China, personal glimpsed of many fine Chinese scientists, and the surprising and amusing cultural differences a Westerner faces in China. The Chinese are not one people, but dozens. There is probably more ethnic and cultural diversity in China than in India, though the thousand languages of China are more closely related than the many Indian tongues.


The discovery of feathered dinosaurs, dinosaurs that might have flown, very early birds, and a number of links between Archaeopteryx and both modern birds and its own ancestors, including dinosaurs that probably did fly, has catapulted Chinese fossils, Chinese scientists, and Chinese science into the international limelight. There are still very few who have visited China, but riches abound for those who do. Now, in the fossil-prone areas, small regional museums like this one (p. 147) abound, showing not just large, "traditional" dinosaurs, but many new discoveries of the smaller, much more abundant (though less often fossilized), feathered dinosaurs that we lived through the Cretaceous extinction event to become today's birds.

The last chapter of the book is polemic. As with any new discovery, there are those who see it differently. The vocal crew that rallies around the moniker BAND (Birds Are Not Dinosaurs) prefer the view that birds evolved from something ancestral to both the feathered dinosaurs and the bird clade. Dr. Morell spends the whole chapter refuting their views. Time will provide its own refuation, should one be needed.

No comments: