Monday, May 25, 2009

Hallucigenia, Corrected

Most people realise that reconstructions of animals from their fossilised remains is a risky business, and that when there are only a few fossil specimens, opportunities for misinterpretation are many. Add to this an investigator who declares `I have a natural temptation to emphasise the unusual', then the probability of error is greatly increased. All these ingredients are present in the case of an organism named Hallucigenia, first described in 1977 by Conway Morris in the journal Palaeontology.

However, new evidence has come to light which suggests that Hallucigenia exists only in our imagination. Lars Ramiskold of the Swedish Museum of Natural History and Hou Xianguang from the Nanjing Institute of Geology and Palaeontology have been studying worm-like fossils from Southern China. They consider that the fossils have a body plan similar to the velvet worms of modern rain forests, but that they were armoured - bearing protective spines. After comparing the characteristics of the Hallucigeniafossils with those of their own, they were able to conclude that the reconstruction was wrong, that Hallucigenia was actually an armoured velvet worm, and that it belongs to the phylum Onychophora.

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