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Walcott, Charles (Doolittle)

animals shale burgess specimens

(1850–1927) US palaeontologist: discovered in the Burgess Shale of British Columbia a vast range of fossilized animals.

Walcott has a strange place in science. His great discovery, made in 1909, was largely misinterpreted by him, and it was many years before others recognized the exceptional role in evolution represented by the creatures he had collected from the Burgess Shale deposits.

Despite his lack of formal education he became his country’s leading scientific administrator. From his first interest in trilobites, when he was a young farm worker, he developed his studies in geology and in 1876 became assistant to the New York State geologist. By 1894 he had risen to become director of the US Geological Survey and, in 1907, he became secretary (ie head) of the Smithsonian Institution and the most powerful figure in science in the USA. Thereafter he added other senior committee posts while retaining his expertise in geology and a special interest in aeronautics; field geology and the problems of the Cambrian rocks were his passionate relaxation.

From the time of his discovery, in the Burgess Shale, of strata rich in the fossils of novel soft-bodied animals, typically a few centimetres long, Walcott and his family spent his vacations there collecting specimens. In total he secured nearly 70 000 and stored them in the Smithsonian in Washington. Nearly 90% are animals and most of the rest algae. Most of the animals are soft-bodied and the remainder have shell-like skeletons; they contain 119 genera in 140 species, with nearly 40% of the genera being arthropods – a phylum of animals with jointed appendages, some specialized for mastication, a well-developed head and usually a hard exoskeleton. They include insects, crustacea, spiders etc.

Walcott studied his specimens with care, but he was highly conservative by nature and this led him to classify his finds within an existing taxonomy and to place these weird animals within an evolutionary sequence continuing from their Cambrian origins to the present. Revision of these ideas began in the late 1960s, with the work of H Whittington, D Briggs and S Conway Morris of the UK, whose laborious dissections gradually allowed three-dimensional reconstructions to be devised from the shale-flattened specimens. The conclusion from their work is that ‘the Burgess Shale includes a disparity in anatomical design never again equalled, and not matched today by all the creatures in all the world’s oceans’ . In terms of evolution most of these designs are ‘losers’ and only a few are ‘winners’ with descendants still existing after 530 million years. Some major problems remain: notably, how did such disparity arise and over such a geologically short time and what factors decided who should win and who would lose? The answers, or even attempts to find them, will inevitably much expand current ideas on the process of evolution.

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