Ophthalmosauridae

Ophthalmosauridae Temporal range: Middle Jurassic-Late Cretaceous, 171.6–93.5 Ma PreЄ Є O S D C P T J K Pg N
Ophthalmosaurus icenicus skeleton
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	†Ichthyosauria
Node:	Ophthalmosauria
Family:	†Ophthalmosauridae Baur, 1887
Subgroups
See text.

Ophthalmosauridae is an extinct family of thunnosaur ichthyosaurs from the Middle Jurassic to the early Late Cretaceous (Bajocian - Cenomanian) of Asia, Australia, Europe, North America and South America.^[1] Currently, the oldest known ophthalmosaurid is Mollesaurus from the early Bajocian of Argentina.^[2] Named by George H. Baur, in 1887, it contains the basal taxa like Ophthalmosaurus.^[1] Appleby (1956) named the taxon Ophthalmosauria which was followed by some authors,^[3][4] but if these two names are synonyms, Ophthalmosauridae has the priority over Ophthalmosauria.^[1]

Phylogeny

Ophthalmosaurus

Ophthalmosauridae is a node-based taxon defined by Ryosuke Motani (1999) as "the last common ancestor of Brachypterygius extremus and Ophthalmosaurus icenicus and all of its descendants". The definition he proposed for Ophthalmosauria was exactly the same.^[3] In this case both definitions are synonyms. The cladogram below follows the topology from a 2010 analysis by Patrick S. Druckenmiller and Erin E. Maxwell.^[4]

Thunnosauria	Ichthyosaurus Stenopterygius "Ophthalmosaurus" natans  Ophthalmosauridae  Aegirosaurus Ophthalmosaurus (type species) Mollesaurus Athabascasaurus Brachypterygius Arthropterygius Caypullisaurus "Platypterygius" hercynicus "Platypterygius" australis (=Longirostria)[5] Platypterygius (type species) Maiaspondylus "Platypterygius" americanus (=Tenuirostria)[5]

Valentin Fischer, Edwige Masure, Maxim S. Arkhangelsky and Pascal Godefroit (2011) described a new genus of Ophthalmosauridae. They redefined it as "the last common ancestor of Arthropterygius chrisorum and Ophthalmosaurus icenicus and all of its descendants". In this case Ophthalmosauria isn't a junior synonym of Ophthalmosauridae. The cladogram below follows Fischer et al. 2011.^[1]

Thunnosauria	Ichthyosaurus Stenopterygius Chacaicosaurus  Ophthalmosauridae  Arthropterygius * Brachypterygius Ophthalmosaurus (type species) Maiaspondylus Mollesaurus Aegirosaurus Sveltonectes "Platypterygius" hercynicus Caypullisaurus Athabascasaurus "Platypterygius" australis (=Longirostria) [5]

*Note: Placement of Ophthalmosauria by definition.

Fischer et al. (2012) described another new genus of Ophthalmosauridae. They defined for the first time two subfamilies within the Ophthalmosauridae, Ophthalmosaurinae and Platypterygiinae. Ophthalmosaurus and Platypterygius were found to be non-monophyletic. Ophthalmosauridae was characterized by a reduced extracondylar area, a plate-like dorsal trochanter, a humerus with a facet for an anterior accessory element and the absence of notching on the paddle elements of the forefin. The cladogram below follows Fischer et al. 2012.^[6]

Thunnosauria	Ichthyosaurus Stenopterygius Chacaicosaurus  Ophthalmosauridae  Arthropterygius *  Ophthalmosaurinae  Mollesaurus Ophthalmosaurus (type species) Baptanodon ("O." natans) Acamptonectes  Platypterygiinae  Brachypterygius Maiaspondylus Aegirosaurus Sveltonectes "Platypterygius" hercynicus Caypullisaurus Athabascasaurus "Platypterygius" australis (=Longirostria)[5]

References

1. Fischer, V.; Masure, E.; Arkhangelsky, M.S.; Godefroit, P. (2011). "A new Barremian (Early Cretaceous) ichthyosaur from western Russia". Journal of Vertebrate Paleontology. 31 (5): 1010–1025. doi:10.1080/02724634.2011.595464.
2. Marta S. Fernández (1999). "A new ichthyosaur from the Los Molles Formation (Early Bajocian), Neuquen Basin, Argentina". Journal of Paleontology. 73 (4): 677–681. JSTOR 1306766.
3. Ryosuke Motani (1999). "Phylogeny of the Ichthyopterygia" (PDF). Journal of Vertebrate Paleontology. 19 (3): 472–495. doi:10.1080/02724634.1999.10011160.
4. 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. Bibcode:2010CaJES..47.1037D. doi:10.1139/E10-028.
5. Arkhangel’sky, M. S., 1998, On the Ichthyosaurian Genus Platypterygius: Palaeontological Journal, v. 32, n. 6, p. 611-615.
6. Valentin Fischer, Michael W. Maisch, Darren Naish, Ralf Kosma, Jeff Liston, Ulrich Joger, Fritz J. Krüger, Judith Pardo Pérez, Jessica Tainsh and Robert M. Appleby (2012). "New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary". PLoS ONE. 7 (1): e29234. doi:10.1371/journal.pone.0029234. PMC 3250416. PMID 22235274.