Ophthalmosauridae

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Ophthalmosauridae
Temporal range: Middle Jurassic-Late Cretaceous, 171.6–93.5 Ma
OphthalmosaurusIcenius-NaturalHistoryMuseum-August23-08.jpg
Ophthalmosaurus icenicus skeleton
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Ichthyosauria
Node: Ophthalmosauria
Family: Ophthalmosauridae
Baur, 1887

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[edit]

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[edit]

  1. ^ a b c d 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. ^ a b Ryosuke Motani (1999). "Phylogeny of the Ichthyopterygia" (PDF). Journal of Vertebrate Paleontology 19 (3): 472–495. 
  4. ^ a b 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. ^ a b c d 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.