Stenopterygius

Taxobox
name = "Stenopterygius"
fossil_range = Early to Mid Jurassic

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image_width = 250px
image_caption = "Stenopterygius quadriscissus" from the Early Jurassic of Germany
regnum = Animalia
phylum = Chordata
classis = Sauropsida
ordo = Ichthyosauria
familia = Stenopterygiidae
genus = "Stenopterygius"
genus_authority = Jaekel, 1904
subdivision_ranks = Species
subdivision =
*"S. quadriscissus" (Von Quenstadt, 1858) Jaekel, 1904 (Type species)
*"S. longifrons" (Owen, 1881) Von Huene, 1939
*"S. megalorhius" Von Huene, 1922
*"S. hauffianus" Von Huene, 1922

"Stenopterygius" is an extinct genus of ichthyosaur from the Early to Middle Jurassic (Toarcian - Aalenian) from Europe (England, France, Germany and Luxembourg). Maximum length was 4 m.Maisch MW, Matzke AT. 2000. The Ichthyosauria. "Stuttgarter Beiträge zur Naturkunde Serie B (Geologie und Paläontologie)" 298: 1-159]

Palaeobiology

"Stenopterygius" was physically similar to the better known "Ichthyosaurus", but had a smaller skull and narrower flippers. Beautifully preserved fossils of "Stenopterygius" have been found in Germany. Its skull was extended into a kind of a beak and was armed with a quantity of large teeth. The limbs had been transformed to fin-like structures. The tail terminated in a large, semicircular, leathery, vertical caudal fin and even a triangular dorsal fin was present.

The habits of "Stenopterygius" were similar to those of present-day dolphins. It spent most of its life in the open sea, where it hunted fish, cephalopods and other animals. The abdominal cavity of skeletons of this ichthyosaur often contains the remains of such food.

One famous fossil is that of a mother and baby that died in childbirth (ichthyosaurs were viviparous). This proved that ichthyosaur infants were born tail-first, just like cetaceans, to prevent them from drowning before fully clearing the birth canal.

References