Reconstruction of the shape and optics of the lenses in the abathochroal-eyed trilobite Neocobboldia Chinlinica

József Gál, Gábor Horváth, Euan N.K. Clarkson

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Until now, the structure and optics of the calcite lenses in abathochroal trilobite eyes have not been investigated. So, the relationship of the abathochroal eye to other types of trilobite eyes has remained unclear. We have reconstructed the exact shape and optics of the lenses in the eodiscid trilobite Neocobbold in chinlinica to determine the mechanism of its abathochroal eye. The distal lens surface has a convex profile, while on the proximal lens surface there is a small central bulge, resulting in an undulating profile. Due to this bulge, the curvature and refractive power of the central region of the lens are greater than those of the peripheral zone. Consequently, the lens is bifocal. However, Neocobboldia could not take advantage of this bifocal property of its tiny lenses because of the diffraction of light and the infinite depth of field in object space. For the same reason, it is also sure that the undulating lower surface of the abathochroal lens did not evolve as a Huygensian profile, correcting for spherical aberration, as suggested earlier. This undulation is a result of the presence of the central bulge, the evolutionary significance of which remains enigmatic. On the basis of our results, we have outlined an evolutionary scenario for development of the optics of the lenses in trilobite eyes.

Original languageEnglish
Pages (from-to)193-204
Number of pages12
JournalHistorical Biology
Issue number4
StatePublished - 2000

Bibliographical note

Funding Information:
This work was supported by a Zoltan Magyary postdoctoral fellowship from the Foundation for Hungarian Higher Education and Research, and by a Janos Bolyai research scholarship from the Hungarian Academy of Science received by G. Horvath. The grant OTKA F-012858 received from the Hungarian National Science Foundation is gratefully acknowledged. Many thanks are due to Riccardo Levi-Setti (Enrico Fermi Institute, University of Chicago, USA), Hansjiir-gen Dahmen (Lehrstuhl fur Biokybernetik, Uni-versitat Tubingen, Germany) and Ronald H. H. Kroger (Anatomisches Institut, Universitat Tubingen), who read and commented on earlier versions of the manuscript.


  • Abathochroal eye
  • Calcite lenses
  • Eodiscid trilobites
  • Neocobboldia chinlinica
  • Optics
  • Triolobite vision

ASJC Scopus subject areas

  • General Agricultural and Biological Sciences


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