Biology:Mollesaurus

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Mollesaurus is an extinct genus of large ophthalmosaurine ichthyosaur known from northwestern Patagonia of Argentina.[1]

Etymology

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]

History of study

Mollesaurus is known from the holotype MOZ 2282 V, articulated partial skeleton which preserved partial skull and most of the vertebral column. It was collected in the Chacaico Sur locality from the Emileia giebeli ammonoid zone of the Los Molles Formation, Cuyo Group, dating to the early Bajocian stage of the Middle Jurassic, about 171.6-170 million years ago. Mollesaurus, along with Chacaicosaurus cayi which was found at the same locality, are the only diagnostic ichthyosaur specimens from the Aalenian-Bathonian interval. It was found near Zapala city of the Neuquén Basin.[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]

Ophthalmosauria
 
Ophthalmosaurinae
 
 
 
 

Acamptonectes densus

 
 
 

Mollesaurus periallus

 
 
 

Ophthalmosaurus natans

 
 

Ophthalmosaurus icenicus

 
 
 
 
 
 
 
 
 

Gengasaurus nicosiai

 
 
 
 

Nannopterygius yasykovi

 
 
 

Nannopterygius enthekiodon

 
 

Nannopterygius saveljeviensis

 
 

Nannopterygius borealis

 
 
 
 
 
 

Arthropterygius volgensis

 
 
 

Arthropterygius lundi

 
 

Arthropterygius thalassonotus

 
 
 

Arthropterygius hoybergeti

 
 

Arthropterygius chrisorum

 
 
 
 
 
 
 
 
 
Platypterygiinae
 
 

Brachypterygius extremus

 
 

Aegirosaurus leptospondylus

 
 
 

Muiscasaurus catheti

 
 
 

Leninia stellans

 
 
 

Sveltonectes insolitus

 
 
 

Athabascasaurus bitumineus

 
 
 

Platypterygius americanus

 
 
 
 

Acuetzpalin carranzai

 
 

Platypterygius sachicarum

 
 

Caypullisaurus bonapartei

 
 
 
 
 
 

Grendelius mordax

 
 

Grendelius alekseevi

 
 

Grendelius pseudoscythicus

 
 

Grendelius zhuravlevi

 
 
 
 
 
 

Undorosaurus kielanae

 
 
 

Undorosaurus nessovi

 
 

Undorosaurus gorodischensis

 
 
 
 
 
 
 
 

Platypterygius australis

 
 
 

Plutoniosaurus bedengensis

 
 

Simbirskiasaurus birjukovi

 
 

Platypterygius hercynicus

 
 

Sisteronia seeleyi

 
 

Platypterygius platydactylus

 
 

Maiaspondylus lindoei

 
 
 
 
 
 
 
 
 
 
 
 
 
 

See also

References

  1. ↑ 1.0 1.1 1.2 Fernández, Marta S. (1999). "A new ichthyosaur from the Los Molles Formation (Early Bajocian), Neuquen Basin, Argentina". Journal of Paleontology 73 (4): 677–681. doi:10.1017/S0022336000032492. Bibcode: 1999JPal...73..677F. 
  2. ↑ Michael W. Maisch; Andreas T. Matzke (2000). "The Ichthyosauria". Stuttgarter Beiträge zur Naturkunde. Serie B (Geologie und Paläontologie) 298: 1–159. https://www.biodiversitylibrary.org/item/278993#page/351/mode/1up. 
  3. ↑ 3.0 3.1 Patrick 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. doi:10.1139/E10-028. Bibcode: 2010CaJES..47.1037D. 
  4. ↑ Fischer, Valentin; Edwige Masure; Maxim S. Arkhangelsky; Pascal Godefroit (2011). "A new Barremian (Early Cretaceous) ichthyosaur from western Russia". Journal of Vertebrate Paleontology 31 (5): 1010–1025. doi:10.1080/02724634.2011.595464. Bibcode: 2011JVPal..31.1010F. https://orbi.uliege.be/handle/2268/92828. 
  5. ↑ Valentin Fischer; Michael W. Maisch; Darren Naish; Ralf Kosma; Jeff Liston; Ulrich Joger; Fritz J. Krüger; Judith Pardo Pérez et al. (2012). "New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary". PLOS ONE 7 (1). doi:10.1371/journal.pone.0029234. PMID 22235274. Bibcode: 2012PLoSO...729234F. 
  6. ↑ Nikolay G. Zverkov; Megan L. Jacobs (2021). "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. 

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