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Acari: Paleontology

Almost 300 species of acariform mites are known as fossils, although this number does include several subfossil oribatid mites belonging to living species. The oldest acariform mites are Devonian, but many groups only make their first appearance in Mesozoic ambers. Oribatids are quite well represented throughout the fossil record thanks to their often heavily sclerotized body; but fossils of many groups with soft, tiny bodies or highly specialised ecologies have never been discovered. Only a handful of parasitiform mites are known as fossils, the oldest of which are some ticks from Cretaceous ambers.

A summary list of fossil spiders and their relatives

Fossil spiders have not been fully cataloged since Bonnet’s Bibliographia Araneorum and are not included in the current World Spider Catalog. Since Bonnet’s time there has been considerable progress in our understanding of the fossil record of spiders – and other arachnids – and numerous new taxa have been described. For an overview see Dunlop & Penney (2012). Spiders remain the single largest fossil group, but our aim here is to offer a summary list of all fossil Chelicerata in their current systematic position; as a first step towards the eventual goal of combining fossil and Recent data within a single arachnological resource. 

http://www.wsc.nmbe.ch/resources/fossils/Fossils16.0.pdf

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