Thunnosauria

Thunnosauria Temporal range: Early Jurassic-Late Cretaceous, 199.6–93.5 Ma PreЄ Є O S D C P T J K Pg N
Ichthyosaurus breviceps fossil
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Ichthyosauria
Node:	†Neoichthyosauria
Node:	†Thunnosauria Motani, 1999
Subgroups
See text.

Thunnosauria (Greek for "tuna lizard" - thunnos meaning "tuna" and sauros meaning "lizard") is an extinct clade of parvipelvian ichthyosaurs from the Early Jurassic to the early Late Cretaceous (Hettangian - Cenomanian) of Asia, Australia, Europe, North America and South America. Named by Ryosuke Motani, in 1999, it contains the basal taxa like Ichthyosaurus and Stenopterygius and the family Ophthalmosauridae. In thunnosaurs, the forefin at least twice as long as the hindfin.^[1][2]

Phylogeny

Thunnosauria is a node-based taxon defined in 1999 as "the last common ancestor of Ichthyosaurus communis and Stenopterygius quadriscissus and all of its descendants".^[1] The cladogram below follows the topology from a 2010 analysis by Patrick S. Druckenmiller and Erin E. Maxwell.^[3]

Thunnosauria	Ichthyosaurus Stenopterygius "Ophthalmosaurus" natans  Ophthalmosauridae  Aegirosaurus Ophthalmosaurus Mollesaurus Athabascasaurus Brachypterygius Arthropterygius Caypullisaurus "Platypterygius" hercynicus "Platypterygius" australis Platypterygius Maiaspondylus "Platypterygius" americanus

References

1. Ryosuke Motani (1999). "Phylogeny of the Ichthyopterygia" (PDF). Journal of Vertebrate Paleontology 19 (3): 472–495. doi:10.1080/02724634.1999.10011160.
2. Michael W. Maisch and Andreas T. Matzke (2000). "The Ichthyosauria" (PDF). Stuttgarter Beiträge zur Naturkunde: Serie B 298: 1–159.
3. Patrick S. Druckenmiller and Erin E. Maxwell (2010). "A new Lower Cretaceous (lower Albian) ichthyosaur genus from the Clearwater Formation, Alberta, Canada". Canadian Journal of Earth Sciences 47 (8): 1037–1053. doi:10.1139/E10-028.