Discovery of some 400 million year-old sensory structures in the compound eyes of trilobites

Fossilised arthropod compound eyes have frequently been described. Among the oldest known are those from the lower Cambrian of the Chengjiang Lagerstätte (China, c 525 Ma). All these compound eyes, though often excellently preserved, however, represent just the outer shells, because soft tissues, or even individual cells, usually do not fossilise. Using modern techniques, including μct-scanning and synchrotron radiation analysis we present the discovery of the sensory cell system of compound eyes, belonging to trilobites around 400 million years old, which allows their description and analysis. They are interpreted as forming part of an apposition-like ommatidium, which is a basic functional type of compound eye present in arthropods of today. Considered in greater detail, it is similar to the compound eye of the horseshoe crab Limulus, generally regarded as a ‘living fossil’, which probably retained this ancient basal system successfully until today.

[1]  J KRIMSKY,et al.  The evolution of vision. , 1957, The West Virginia medical journal.

[2]  B. Schoenemann.  The eyes of a tiny ‘Orsten’ crustacean – A compound eye at receptor level? , 2013, Vision Research.

[3]  T. Cronin,et al.  Comparison of fossilized schizochroal compound eyes of phacopid trilobites with eyes of modern marine crustaceans and other arthropods , 1989 .

[4]  Andrew R. Parker,et al.  Colour in Burgess Shale animals and the effect of light on evolution in the Cambrian , 1998, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[5]  John R. Paterson,et al.  Modern optics in exceptionally preserved eyes of Early Cambrian arthropods from Australia , 2011, Nature.

[6]  Gengo Tanaka,et al.  An exceptionally well-preserved Eocene dolichopodid fly eye: function and evolutionary significance , 2009, Proceedings of the Royal Society B: Biological Sciences.

[7]  L. David,et al.  The puzzling eye of Phacops , 2003 .

[8]  E. Gaten.  Optics and phylogeny: is there an insight? The evolution of superposition eyes in the Decapoda (Crustacea) , 1998 .

[9]  J. A. Westfall,et al.  Fine structure of the eye of peripatus (Onychophora) , 1965, Zeitschrift für Zellforschung und Mikroskopische Anatomie.

[10]  Jian Han,et al.  A miniscule optimized visual system in the Lower Cambrian , 2009 .

[11]  G. Edgecombe,et al.  Acute vision in the giant Cambrian predator Anomalocaris and the origin of compound eyes , 2011, Nature.

[12]  E. Clarkson.  The evolution of the eye in trilobites , 1973 .

[13]  W. H. Fahrenbach.  The morphology of the eyes of Limulus , 1968, Zeitschrift für Zellforschung und Mikroskopische Anatomie.

[14]  G. Horváth,et al.  The eyes of trilobites: The oldest preserved visual system. , 2006, Arthropod structure & development.

[15]  E. Clarkson,et al.  Ontogeny of the Carboniferous trilobite Paladin eichwaldi shunnerensis (King 1914) , 1991, Transactions of the Royal Society of Edinburgh: Earth Sciences.

[16]  M. Wiener,et al.  Animal eyes. , 1957, The American orthoptic journal.

[17]  K. Towe,et al.  Trilobite Eyes: Calcified Lenses in vivo , 1973, Science.

[18]  R. Hoy,et al.  Chunk versus point sampling: visual imaging in a small insect. , 1999, Science.

[19]  A. Gray,et al.  I. THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION , 1963 .

[20]  Georg Mayer,et al.  Structure and development of onychophoran eyes: what is the ancestral visual organ in arthropods? , 2006, Arthropod structure & development.

[21]  E. Clarkson,et al.  Eyes and vision in the Chengjiang arthropod Isoxys indicating adaptation to habitat , 2011 .

[22]  Euan N. K. Clarkson,et al.  Trilobite eyes and the optics of Des Cartes and Huygens , 1975, Nature.

[23]  Trilobite vision; a comparison of schizochroal and holochroal eyes with the compound eyes of modern arthropods , 1993 .

[24]  E. Clarkson,et al.  The eyes of Leanchoilia , 2012 .