The occasion of Nature‘s publication of 15 Evolutionary Gems, synopses of recent research from its pages that deepens our understanding of the process of evolution, prompted some pruning and dusting of my bookmark files. So here let us take note of
- The National Center for Science Education (NCSE), “a not-for-profit, membership organization providing information and resources for schools, parents and concerned citizens working to keep evolution in public school science education”
- Science, Evolution, and Creationism, a short book by the National Academy of Sciences
- Robert L. Park’s essay, “The Seven Warning Signs of Bogus Science”: “1. The discoverer pitches the claim directly to the media…. 2. The discoverer says that a powerful establishment is trying to suppress his or her work.”
The papers summarized in the Nature document examine evidence collected by field observation, at the molecular level in the lab, and from the fossil record. Of particular note to “no transitional forms” deniers is the discussion of newly-described specimens found in China.
In the 1980s, deposits from the early Cretaceous period (about 125 million years ago) in the Liaoning Province in northern China vindicated these speculations in the most dramatic fashion, with discoveries of primitive birds in abundance — alongside dinosaurs with feathers, and feather-like plumage. Starting with the discovery of the small theropod Sinosauropteryx by Pei-ji Chen from China’s Nanjing Institute of Geology and Palaeontology and his colleagues, a variety of feather-clad forms have been found. Many of these feathered dinosaurs could not possibly have flown, showing that feathers first evolved for reasons other than flight, possibly for sexual display or thermal insulation, for instance. In 2008, Fucheng Zhang and his colleagues from the Chinese Academy of Sciences in Beijing announced the bizarre creature Epidexipteryx, a small dinosaur clad in downy plumage, and sporting four long plumes from its tail. Palaeontologists are now beginning to think that their speculations weren’t nearly wild enough, and that feathers were indeed quite common in dinosaurs.
The discovery of feathered dinosaurs not only vindicated the idea of transitional forms, but also showed that evolution has a way of coming up with a dazzling variety of solutions when we had no idea that there were even problems. Flight could have been no more than an additional opportunity that presented itself to creatures already clothed in feathers.