Ichthyosauria: Thunnosauria

Taxa on this Page

1. Ichthyosaurus X
2. Stenopterygius X
3. Thunnosauria X

Descriptions

Thunnosauria: Chacaicosaurus

Range: Late Triassic, but mostly Early Jurassic to middle Cretaceous

Phylogeny: Parvipelvia: Temnodontosaurus + Eurhinosauria + *: Stenopterygius + (Ichthyosaurus + Ophthalmosauria).

Characters: diapophyses & parapophyses round [S97]; diapophysis on anterior spine attaches to neural arch & moves down centrum to fuse with parapophysis in sacral vertebrae [S97]; parapophysis also moves ventrally, but not as much; caudal vertebrae with 1 articular facet [S97]; pubis & ischium rod-like [M97].

References: McGowan (1997) [M97]; Sander (1997) [S97].

Note: It will be disappointing if this turns out not to be a clade, since it is so aptly named. These are, indeed, the tuna-lizards. ATW020517.

Stenopterygius: S. quadriscissus Quenstedt

Range: Early Jurassic to Middle Jurassic of Europe & South America.

Phylogeny: Thunnosauria: (Ichthyosaurus + Ophthalmosauria) + *.

Characters: to 2-3 m; generally similar to Ichthyosaurus; small head; see image for unusual structure of skull; exceptionally large orbit compared to size of head; dramatic overbite; narrow paddles (hence the name).

Image:  fossil replica image from www.fossilien.de. Larger image and various close-ups at this site.

Links: Prehistoric World Images - Stenopterygius - Jurassic reptile; Stenopterygius; Stenopterygius quadriscissus; Weight; Biology 356 (detail of forelimb); jurassic images (another strikingly beautiful image from Doug Henderson); Dinosaurios: Stenopterygius; Fossilienverkauf remarkable selection of photos); Gallery of fossil amphibians, reptiles and birds; Bernstein, Fossilien, Ammoniten, Repliken und vieles mehr zum Kaufen; Neuigkeiten aus der Wissenschaft; Bilder aus der Fossilien-Sammlung von Armin Bauer; Ichthyosaur Stenopterygius quadriscissus fossil image); Stenopterygius　ステノプテリギウス (model); Dinowelt-Stenopterygius; Ichthyosaurier Stenopterygius quadriscissus Quenstedt - ... fossil images); [스테노프테리기우스(Stenopterygius)] Korean: several good images); Gallery of fossil amphibians, reptiles and birds very nice, but tiny image); 標本解説　ステノプテリギュウス. ATW020517.

Ichthyosaurus:

Range: Late Triassic(!?) to Early Jurassic of Europe & North America. [C97a]

Phylogeny: Thunnosauria:: Ophthalmosauria + *.

Characters: ~2 m; jaws of equal length; maxilla relatively small [M97]; orbits enlarged [M97]; narrow posorbital region [M97]; pronounced dorsal fin; nares very close to orbits; polydactyly;

Links: Ichthyosaurus teunuirostris (Italian); No. 973: Owen's Ichthyosaurus; The Field Museum of Natural History Ichthyosaurus; Marine Reptiles: Ichthyosaur: Ichthyosaurus; Ichthyosaure - Reptile marin de l'Ere Secondaire; Dinosaurios: Ichthyosaurus; Hawkins 1834 - Page 14 - The Ichthyosaurus Chiroligostinus (not certain this is Ichthyosaurus itself, but an incredible site all the same).

References: Callaway (1997a) [C97a]; McGowan (1991) [M91]; McGowan 1997) [M97]. ATW020517.