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Eyes and vision in the coeval F urongian trilobites S phaerophthalmus alatus ( B oeck, 1938) and C tenopyge ( M esoctenopyge ) tumida W estergård, 1922, from B ornholm, D enmark
Author(s) -
Schoenemann Brigitte,
Clarkson Euan N. K.
Publication year - 2015
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12128
Subject(s) - trilobite , biology , benthic zone , zoology , paleontology , evolutionary biology , ecology , ordovician
The two olenid species S phaerophthalmus alatus ( B oeck, 1838) and C tenopyge ( M esoctenopyge) tumida W estergård, 1922, occur together in the C tenopyge tumida Z one ( Z one 19) of the F urongian of S candinavia. M aterial from B ornholm, D enmark, forms the basis of this study of the morphology and partial ontogeny of the eyes. The eyes of both species are directed laterally and have virtually panoramic vision, looking out sideways like those of a rabbit. The eye of S . alatus is comparatively smaller, with fewer lenses and a larger eye parameter; calculations show that this trilobite was adapted for dim light intensity, possibly suggesting a vagrant benthic habit. C tenopyge ( M esoctenopyge) tumida , with a smaller eye parameter, was adapted for a higher light intensity, and this trilobite was most likely a pelagic swimmer. The two species, although preserved together, inhabited different levels in the water column.