Mixosaurus cornalianus (Baur 1887, Middle Triassic, 1-2m in length) is a derived ichthyosaur that retained a primitive tail. The flippers were similar in size. The cranium was depressed into twin basins on either side of a frontal/parietal crest. The neural spines were tall and narrow.

Derived from a sister to Phalarodon, Mixosaurus was a sister to Cymbospondylus.

not Aegirosaurus leptospondylus Delsett et al. 2022; JME-SOS-08369, Late Jurassic Solnhofen) was originally considered a relative of Ophthalmosaurus. Here it nests as a late-surviving mixosaur with a kinked tail and a taller caudal fin (here broken off).

The neotype of Aegirosaurus nests elsewhere, with Hauffiopteryx.

Baur G 1887. Über den Ursprung der Extremitäten der Ichthyopterygier. Jber. Mitt.
oberrhein. geol. Verein, 20: 17–20, 1 pl.; Stuttgart.

Delsett LL, Friss H, Kölbl-Ebert and Hurum JH 2022. The soft tissue and skeletal anatomy of two Late Jurassic ichthyosaur specimens from the Solnhofen archipelago. PeerJ 10:e13173 DOI 10.7717/peerj.13173

wiki/Mixosaurus
wiki/Aegirosaurus