Mollesaurus was named by Marta S. Fernández in 1999 and the type species is Mollesaurus periallus. The generic name is derived from the name of the Los Molles Formation, where the holotype was collected, and sauros, Greek for "lizard". The specific name is derived from periallos, Greek for "before all others", in reference to the fact that it is the oldest ophthalmosaurid and one of the oldest thunnosaurs.[1]
Maisch and Matzke (2000) regarded Mollesaurus to be a species of Ophthalmosaurus.[2] However, all recent cladistic analyses found that Mollesaurus is a valid genus of ophthalmosaurid.[3][4] Patrick S. Druckenmiller and Erin E. Maxwell (2010) found it to be the basalmost member of the ophthalmosaurid lineage that included Brachypterygius, Caypullisaurus and Platypterygius (but not Ophthalmosaurus).[3]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) found it to be the basalmost member of Ophthalmosaurinae.[5]
Phylogeny
The following cladogram shows a possible phylogenetic position of Mollesaurus in Ophthalmosauridae according to the analysis performed by Zverkov and Jacobs (2020).[6]
^Michael W. Maisch & Andreas T. Matzke (2000). "The Ichthyosauria". Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie). 298: 1–159.
^ abPatrick S. Druckenmiller & 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.
^Nikolay G. Zverkov & Megan L. Jacobs (2021) [2020]. "Revision of Nannopterygius (Ichthyosauria: Ophthalmosauridae): reappraisal of the 'inaccessible' holotype resolves a taxonomic tangle and reveals an obscure ophthalmosaurid lineage with a wide distribution". Zoological Journal of the Linnean Society. 191 (1): 228–275. doi:10.1093/zoolinnean/zlaa028.
