Nature 352, 62 - 64 (04 July 1991); doi:10.1038/352062a0

Dorsal nostrils and hydrodynamically driven underwater olfaction in plesiosaurs

Arthur R. I Cruickshank, Philip G Small^* & Michael A Taylor

Leicestershire Museums, Arts and Records Service, 96 New Walk, Leicester LEI 6TD, UK
^* X-Ray Department, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK

THE dorsally placed external nostrils of plesiosaurs are usually regarded as an adaptation to breathing in those extinct marine reptiles. We suggest instead that the narial system was used in underwater olfaction. The internal nares are anterior to the external nares. Hydrodynamic pressure during swimming forced water into the mouth, along palatal grooves into the scoop-shaped internal nares and up short ducts, presumably lined with olfactory epithelia. Alternatively, or additionally, the so far unlocated Jacobson's organ detected particulate matter. The water was sucked out through the external nares by hydrodynamic pressures generated by fast flow over the convex upper surface of the head.

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