Gerastos
{{Short description|Extinct genus of trilobites}}
{{Automatic taxobox
| fossil_range = {{fossilrange|409|388|Early-Middle Devonian}}
| image = Gerastos tuberculatus 20170317.jpg
| image_caption = Gerastos tuberculatus from Morocco
| image2 = Gerastos_sp._trilobite_Morocco.jpg
| image2_caption = Gerastos sp. from Morocco
| taxon = Gerastos
| authority = Goldfuss, 1843
| subdivision_ranks = Species
| subdivision = {{specieslist
|G. granulosus|Goldfuss, 1843
|G. kesselaeri|Van Viersen, Taghon & Magrean, 2019{{Cite journal|author1=Allart P. van Viersen |author2=Peter Taghon |author3=Benedikt Magrean |year=2019 |title=Early Middle Devonian trilobites and events in the Nismes – Vireux-Molhain area, southern border of the Dinant Synclinorium (Belgium, northern France) |journal=Geologica Belgica |volume=22 |issue=1–2 |pages=7–33 |doi=10.20341/gb.2019.001 |doi-access=free }}
|G. silvicultrix|Van Viersen, Taghon & Magrean, 2019
|G. tuberculatus marocensis|Chatterton et al., 2006
}}
}}
Gerastos is a genus of proetid trilobite in the family Proetidae that lived between the Pragian and Eifelian of the Lower-Middle Devonian, spanning approximately 21 million years.{{Cite web|url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=259049|title=Fossilworks: Hollardops|website=fossilworks.org|access-date=17 December 2021}}
It was described by Goldfuss in 1843.
Distribution
Gerastos has been found in the Devonian of Belgium, Germany, the Czech Republic and Morocco.
Description
Gerastos has holochroal eyes situated to the side of its enlarged glabella region of the cephalon. The surface of the cephalon can be smooth or covered with pustules.{{Cite journal|last1=Van Viersen|first1=Allart|last2=Prescher|first2=Harald|date=2008-10-31|title=Devonian Proetidae (Trilobita) from the Ardennes Massif (Belgium, N France) and the Eifel Hills (W Germany)|url=https://www.researchgate.net/publication/256474898|journal=Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre|volume=78|pages=9–29}}{{Cite journal|last1=Gibb|first1=Stacey|last2=Chatterton|first2=Brian|date=2010-01-01|title=Gerastos (Order Proetida; Class Trilobita) from the Lower to Middle Devonian of the southern Moroccan Anti-Atlas region|url=https://www.researchgate.net/publication/259583808|journal=Palaeontographica Canadiana|volume=29|pages=1–89}}
Length rarely exceeds 3 cm.{{citation needed|date=July 2018}}