A striking #character of adult #mites in #Histiostomatidae (#Astigmata) is a highly #sclerotized area on the upper surface of #proterosoma. Its #latticelike #structure forms a #taxonomically relevant #symmetrical #pattern of windows, for which I introduced a #nomenclature in my PhD thesis. This area is a site of #muscleorigins (see #SEM section through a bigger specimen of #Acaridae).
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After the #Devonian #extinction_event, #crinoids (sea lilies) became an important group. Until the Permian - Triassic extinction event crinoids were one of the main #reef builders. After this extinction event, it suffered #taxonomically and the predators that appeared hindered crinoids recovery. Currently, only those crinoids that can move have survived. Imagine a tree with its branches that are used as hands for movement.

Video by https://palaeo-electronica.org/2007_1/crinoid/fig3.htm

#paleontology #nature