Chelifores, chelicerae, and invertebrate evolution


One of the most evocative creatures of the Cambrian is Anomalocaris, an arthropod with a pair of prominent, articulated appendages at the front of its head. Those things are called great appendages, and they were thought to be unique to certain groups of arthropods that are now extinct. A while back, I reported on a study of pycnogonids, the sea spiders, that appeared to show that that might not be the case: on the basis of neural organization and innervation, that study showed that the way pycnogonid chelifores (a pair of large, fang-like structures at the front of the head) were innervated suggested that they were homologous to great appendages. I thought that was pretty darned cool; a relic of a grand Cambrian clade was swimming around in our modern oceans.

However, a new report by Jager et al. suggests that that interpretation may be flawed, and that sea spider chelifores are actually homologous to the chelicerae of spiders.

Continue reading "Chelifores, chelicerae, and invertebrate evolution" (on Pharyngula)


Cool post… last summer I got to hike up to one of the Burgess Shale sites in the Canadian Rockies and we saw some Anomalocaris fossils - very cool!!

Just think, if the anomalocarids had made it past the Cambrian, maybe there’d be no squid.

Great NOODLY Apendages? In His image, indeed!

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This page contains a single entry by PZ Myers published on May 26, 2006 9:55 AM.

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