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Nannopterygius enthekiodon

Nannopterygius is an enigmatic and unusual ichthyosaur from the Upper Jurassic of the U.K. and possibly Germany.  Like all ichthyosaurs from the Jurassic and later, Nannopterygius has a streamlined, dolphin-like shape with a narrow but deep crescent-shaped tail fin.  Nannopterygius also has large eyes which is characteristic of the ophthalmosaurid ichthyosaurs.  What is unusual about Nannopterygius is that it has very small paddles compared to its body size, hence its name meaning ‘small wing’.  It is likely that Nannopterygius was using its paddles less, or in a different way to other ichthyosaurs.

Nannopterygius is known from only one near-complete specimen — which can be seen in the Marine Reptile Gallery of the Natural History Museum, London — and a few other pieces which are not diagnostic.  There has been almost no study done on this ichthyosaur since it was first discovered and named in 1871.



Nannopterygius enthekiodon   


Hulke, 1870

Meaning of the generic name

"Small wing", after the unusually small paddles.
 Meaning of the specific name

 "Inserted tooth", from the amount of cementum forming a 'sheath'.


Length: 2.5 m (8 ft).


Holotype NHMUK 46497, largely complete, but flattened specimen.  Little other material, none diagnostic: NHMUK 46497a, R1197, 46473e, 47424, R5832.

Age and Distribution

Horizon: Kimmeridge Clay (Kimmeridgian, Upper Jurassic)
Locality: Kimmeridge Bay, Dorset, U.K.


Ichthyopterygia: Ichthyosauria: Thunnosauria

 Further Reading


Hulke, J. 1871. Note on an Ichthyosaurus (I. enthekiodon)from Kimmeridge Bay, Dorset. Quarterly Journal of the Geological Society, 27, 440–441.

Maisch, M. W. and Matzke, A. T. 2000. The Ichthyosauria. Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie), 298, 1–159.

McGowan, C. and Motani, R. 2003. Ichthyopterygia. In Sues, H.-D. Handbook of Palaeoherpetology, Volume 8. Verlag Dr Friedrich Pfeil, Munich, 175 pp, 19 pls.



Nannopterygius enthekiodon, image care of Sandra Chapman.  Copyright © Natural History Museum, London.
Image reconstruction of 
Nannopterygius enthekiodon
Copyright © N. Tamura.