Suevoleviathan: the long and the short of those jaws

Adding taxa
to the large reptile tree (LRT, 1328 taxa) boughts us to derived ichthyosaurs yesterday and today. I added the GPIT 328/4/5 specimen attributed to Suevoleviathan (Figs. 1–3, von Huene 1926, Maisch 1998, Maxwell 2018), which has a much shorter mandible than rostrum when reconstructed. This could be due to damage and loss as the premaxilla is clearly damaged, but retained. Then again, this taxon nests with Eurhinosaurus, famous for its overbite (Fig. 4).

Figure 2. The GPIT specimen attributed to Suevoleviathan has a longer rostrum than mandible.

Figure 2. The GPIT 328/4/5 specimen attributed to Suevoleviathan has a longer rostrum than mandible.

Then I discovered the holotype of Suevoleviathan
(Maisch 1998, Fig. 3) and it had jaws of equal length.

Figure 3. The holotype of Suevoleviathan (Maisch 1998) has jaws of equal length, but nests with the specimen in figure 2.

Figure 3. The holotype of Suevoleviathan (Maisch 1998) has jaws of equal length, but nests with the specimen in figure 2.

I panicked.
There was only one thing to do.

Figure 1. Subset of the LRT focusing on the clade Ichthyosauromorpha.

Figure 1. Subset of the LRT focusing on the clade Ichthyosauromorpha.

I added the holotype to the LRT,
and discovered both Suevoleviathans nested together… strongly (Fig. 3). Other than the distinctly different jaws no other tested ichthyosaur, or any other tested taxon, pulled these two apart. So… are they cousins? Or genders?

Here is the ‘lost’ holotype (Fig. 3, Maxwell 2018).

Figure 3. The 'lost' holotype of Suevoleviathan from Maxwell 2018.

Figure 3. The ‘lost’ holotype of Suevoleviathan from Maxwell 2018. One of the few holotypes that could be considered a holy-type based on its configuration.

Figure 1. Eurhinosaurus, a derived ichthyosaur, in several views.

Figure 4. Eurhinosaurus, a derived ichthyosaur, in several views.

References
Maisch MW 1998. A new ichthyosaur genus from the Posidonia Shale (Lower Toarcian, Jurassic) of Holzmaden, SW-Germany with comments on the phylogeny of post-Triassic ichthyosaurs. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 209: 47–78.
Maxwell EE 2018. Redescription of the ‘lost’ holotype of Suevoleviathan integer (Bronn, 1844) (Reptilia: Ichthyosauria). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1439833.

wiki/Suevoleviathan

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