about Arachnid Fossils

about Arachnid Fossils
Chelicerata: Arachnida
(including spiders, scorpions, pseudoscorpions)

 

 

 

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It should not surprise that Arachnids have enjoyed phenomenal survival success. The most diverse of land-based predators that appeared in Silurian time (Jeran, 1990) owe much of their success to co-evolution with their primary prey, Class Insecta. However, scorpion fossils have been found from the Silurian and acarid fossils from the Devonian. The oldest known spider, Attercopus, was found in Middle Devonian strata in New York (Selden et al. 1991). Early spiders from the Carboniferous period have segmented abdomens not present in their ancestors. Thus, early in the time that life was movingfrom marine to terrestrial environments, the Arachnids were evolving to fill their predatory niches.

Also not surprising is that where insects are found as fossils, so are spiders. However, like insects their thin exoskeltons are not readily fossilized. Fossil arachnids are, however, widespread in fossil amber, sometimes caught in the act of predation when caught in the sticky resin. Other Arachnid behaviors can sometimes be caught in amber, such as cannibalism during mating shown in the picture to the right (click picture for more and larger pictures).

Arachnida Classification

	Order	Common Name
Arachnida	Araneae	spiders
	Palpigradi	micro whipscorpions
	Amblypygi	whipscorpions with no tail
	Thelyphonida	whiptailed scorpions, vinegaroons, uropygids
	Schizomida	similar to whipscorpions
	Ricinulei	hooded tickspider - very small order
	Acari	ticks, mites
	Opiliones	harvestmen (daddy-long legs)
	Scorpionida	scorpions and extinct progenitors
	Pseudoscorpiones	pseudoscorpions, bookscorpions
	Solifugae	wind scorpions, camel spiders, sun spiders, solugids

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