SCI/TECH: Ancient Sea Spider Fossils Discovered In Volcanic Ash, page 1

Volcanic ash that trapped ancient sea life and later deposition of carbonate solids in the cavities created this fossil of an ancient sea spider Haliestes dasos with such remarkable details that enabled the scientists to create a virtual reconstruction of the species. This discovery makes Haliestes dasos the earliest known adult sea spider by 35 million years. The discovery also suggests that the sea spiders are indeed related to land spiders, scorpions, ticks, and mites - which was controversial earlier.

www.sciencedaily.com
New Haven, Conn. � Volcanic ash that encased and preserved sea life in the Silurian age 425 million years ago near Herefordshire, UK has yielded fossils of an ancient sea spider, or pycnogonid, one of the most unusual types of arthropod in the seas today.

Sea spiders are soft-bodied arthropods, found widely in modern oceans. For two-centuries there has been a controversy about the relationship of sea spiders to land spiders, scorpions, ticks and mites because of their unique body form. Sea spiders have a long proboscis and unusual limb structures used in mating and carrying brooding embryos. The fossil record of their relationship is sparse because of their delicate nature.

The research was carried out as part of a project on the Herefordshire fauna by a team made up of Derek Siveter and Mark Sutton at Oxford, Derek Briggs at Yale, and David Siveter at Leicester. The group has made a number of other spectacular finds of soft-bodied organisms in the same deposit including crustaceans, a worm-like mollusc, a polychaete worm, and a starfish, and much that remains to be described.

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Because of the delicacy of soft-bodied sea spiders, there are hardly a few fossil records. Therefore, it is amazing to find that this Silurian spider was preserved with such perfection. Reconstruction images can be seen in the next post. Technology used in the analysis is amazing too - grinding a few microns at a time with each slice digitally imaged and reconstructed.

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