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Eyes? Right!

Trilobites evolved two forms of eyes, "Holochroal" and "Schizochroal." Most seeing trilobites (some lost their sight because of environmental factors), both the most primitive and the last survivers had holochroal eyes much like dragon flies. In the Ordovician period the Phacopid form of trilobites developed lenses that were separated or divided from each other, hence the name "Schizochroal." Herein we illustrate both froms from trilobites collected in Bolivia.

Holochroal Eyes
Hoekaspis yahuari Ordovician Asaphid
Hoekaspis yahuari - Large
Schizochroal Eyes
Wolfartaspis cornutus Devonian Calmoniid
Wolfartaspis cornutus - Detail
Fenestraspis amauta Devonian Dalmanitid
Fenestraspis amauta - Large
World Record: Approx. 860 facets
Francovichia branisai Devonian Dalmanitid
Francovichia branisai - Large
Blind
Cryptolithus tesselatus Ordovician Trinucleid
Cryptolithus tesselatus - Detail
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Created March, 2001