Why did some ichthyosaurs have such large eyes?

2002/02/15 by Stuart Humphries, Graeme D. Ruxton · 2 citations
Agricultural and Biological Sciences · Environmental Science · #Cephalopods and Marine Biology #Ichthyology and Marine Biology #Amphibian and Reptile Biology

paper · doi:10.1242/jeb.205.4.439

Abstract

Many species of extinct marine ichthyosaurs had much larger eyes for their body size than would be expected of extant marine mammals and reptiles. Sensitivity to low light at great depth for the deep-diving genus Ophthalmosaurus has recently been suggested as the reason for the large eyes of these animals. Here, we discuss the implications for vision at such depths and consider other optical factors determining eye size. We suggest that the large eyes of ichthyosaurs are more likely to be the result of simultaneous selection for both sensitivity to low light and visual acuity. The importance of the evolutionary history of extant marine mammals and extinct ichthyosaurs is discussed, as are ecological factors driving both acuity and sensitivity.

Cited by

• Evolution of orbit size in toothed whales (Artiodactyla: Odontoceti)
• Palaeoecology of the marine reptiles of the Redwater Shale Member of the Sundance Formation (Jurassic) of central Wyoming, USA

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