Carl Zimmer in his blog, The Loom:
Last week the world press took note of a fish hauled up off the coast of Zanzibar. (AP, Reuters). Why did they care? Because the animal was one of the most celebrated fish of the sea: it was a coelacanth.
The coelacanth is an ugly, bucket-mouthed creature. At first scientists only knew it from its fossils, the youngest of which was 70 million years old. In 1938, however, a flesh-and-blood coelacanth was dredged up near East London, South Africa. The five-foot long beast had many of the hallmarks of fossil coelacanths, such as hollow spines in their vertebrae, peculiar lobe-shaped fins, and a joint dividing its eye and “nose” from its brain and ears. The coelacanth became a celebrity
in the, hailed as a “living fossil.”
Its fame was reinforced by its elusiveness. It was not until 1952 that a biologist found a second coelacanth, caught this time off the Comoros Islands. Scientists chased the coelacanth so doggedly in part because of what it might reveal about ourselves. Fossils of the coelacanth lineage dated back over 300 million years to the Devonian Period. They belonged to the same group of fishes as our own ancestors (known now as lobe-fins). While the ancestors of coelacanths stayed in the water, our own fishy ancestors climbed on land and evolved into mammals, birds, reptiles, and amphibians. (See my book At the Water’s Edge for more on this transition.)