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Schoenemann, B. & Clarkson, E.N.K. 2012: The eyes of Leanchoilia. Lethaia, Vol. 45, pp. 524–531.

Leanchoilia is one of the commonest non-trilobite arthropod taxa of the Lower and Middle Cambrian. It has recently been regarded to be part of the ‘short great appendage arthropods’ clade and is normally considered a predator, both on account of its raptorial appendages and serial midgut digestive glands. The presence or absence of eyes has been one of the most controversial aspects of its morphology, despite pedunculate eyes having been described in the original descriptions of L. superlata (Walcott 1912) and L. illecebrosa Hou 1987. Other authors considered all species of this genus to be blind. There are two pairs of pits on the head, which have been interpreted as eyes attached near the front of the headshield. Pedunculate eyes have been found in four of about fifty specimens of L. illecebrosa from the Chengjiang and Haikou areas. They are delicate and slender, which explains their rare preservation. Distally they are structured like a bunch of grapes, with about 100 spherical units, presumably lenses, each with a diameter of about 55 μm indicating, by calculation, adaptation to dim light. They probably could detect movement, but could not form images. Furthermore, L. illecebrosa possesses two, probably ventral, median eyes, autapomorphies of euarthropods. Thus, like many modern Euarthropoda, L. illecebrosa has two kinds of eyes – two stalked ventral eyes and two pairs of probably ventral (ocellar) median eyes. Its short stalked eyes, orientated downwards and covered by the headshield, suggest that species of Leanchoilia were benthic animals, feeding on benthic or infaunal animals. □Arthropoda, Burgess Shale, Cambrian, Chengjiang, Compound eye, Lagerstätte, Leanchoilia.