Ichthyosauria

Holotype specimen TMP 2000.29.01 of the ophthalmosaurian ichthyosaur Athabascasaurus bitumineus from the Lower Cretaceous Clearwater Formation of Alberta, in Royal Tyrrell Museum, Drumheller, Alberta, Canada.

Californosaurus perrini, an ichthyosaur from the Late Triassic of North America, pencil drawing

Californosaurus perrini, an ichthyosaur from the Late Triassic of North America, pencil drawing

Various fossils pertaining to the holotype of the Triassic ichthyosaur Toretocnemus californicus. This image is derived from plate 24 in Merriam (1903), done by an uncredited artist. The arrangement of the individual figures has been modified from the original. Original description: Toretocnemus californicus n. gen. and sp. Figures reproduced natural size from the type specimen. Fig. 1. — Inferior side of right posterior limb. t, tibia. Fig. 2. — Right anterior limb. r, radius. Fig. 3.— Pelvic arch. Fig. 4. — Middle dorsal vertebrae and a rib from the same region.

Early Triassic marine vertebrate apex predators during the Griesbachian to Smithian interval (left) and the Spathian to Anisian interval (right). Predators not exactly to scale; see text and Tables S1–S2 for details on body size and stratigraphic occurrence. Marine vertebrate apex predators: 1, Wantzosaurus (trematosaurid ‘amphibian’); 2, Fadenia (eugeneodontiform chondrichthyan); 3, Saurichthys (actinopterygian ambush predator); 4, Rebellatrix (fork-tailed actinistian); 5, Hovasaurus (‘younginiform’ diapsid reptile); 6, Birgeria (fast-swimming predatory actinopterygian); 7, Aphaneramma (trematosaurid ‘amphibian’); 8, Bobasatrania (durophagous actinopterygian); 9, hybodontoid chondrichthyan with durophagous (e.g. Acrodus, Palaeobates) or tearing-type dentition (e.g. Hybodus); 10, e.g., Mylacanthus (durophagous actinistian); 11, Tanystropheus (protorosaurian reptile); 12, Corosaurus (sauropterygian reptile); 13, e.g., Ticinepomis (actinistian); 14, Mixosaurus (small ichthyosaur); 15, large cymbospondylid/shastasaurid ichthyosaur; 16, neoselachian chondrichthyan; 17, Omphalosaurus skeleton (possible durophagous ichthyosaur); 18, Placodus (durophagous sauropterygian reptile).

Early Triassic marine vertebrate apex predators during the Griesbachian to Smithian interval (left) and the Spathian to Anisian interval (right). Predators not exactly to scale; see text and Tables S1–S2 for details on body size and stratigraphic occurrence. Marine vertebrate apex predators: 1, Wantzosaurus (trematosaurid ‘amphibian’); 2, Fadenia (eugeneodontiform chondrichthyan); 3, Saurichthys (actinopterygian ambush predator); 4, Rebellatrix (fork-tailed actinistian); 5, Hovasaurus (‘younginiform’ diapsid reptile); 6, Birgeria (fast-swimming predatory actinopterygian); 7, Aphaneramma (trematosaurid ‘amphibian’); 8, Bobasatrania (durophagous actinopterygian); 9, hybodontoid chondrichthyan with durophagous (e.g. Acrodus, Palaeobates) or tearing-type dentition (e.g. Hybodus); 10, e.g., Mylacanthus (durophagous actinistian); 11, Tanystropheus (protorosaurian reptile); 12, Corosaurus (sauropterygian reptile); 13, e.g., Ticinepomis (actinistian); 14, Mixosaurus (small ichthyosaur); 15, large cymbospondylid/shastasaurid ichthyosaur; 16, neoselachian chondrichthyan; 17, Omphalosaurus skeleton (possible durophagous ichthyosaur); 18, Placodus (durophagous sauropterygian reptile).

Mixosaurus Ichthyosaur fossil prepared by Fossil Shack

Mixosaurus Ichthyosaur fossil prepared by Fossil Shack

Figure description from the paper: "The segmented model of right lateral side of the skull of mixosaurid ichthyosaur Phalarodon fraasi (Merriam, 1910) PMO 235.393, from the Botneheia Formation, Middle Triassic of the Isfjorden area in Spitsbergen, Svalbard." References: Roberts, A.J.; Engelschiøn, V.S.; Hurum, J.H. (2022). "First three-dimensional skull of the Middle Triassic mixosaurid ichthyosaur Phalarodon fraasi from Svalbard, Norway". Acta Palaeontologica Polonica 67 (1): 51–62. DOI:https://doi.org/10.4202/app.00915.2021.

Figure description from the paper: "The segmented model of right lateral side of the skull of mixosaurid ichthyosaur Phalarodon fraasi (Merriam, 1910) PMO 235.393, from the Botneheia Formation, Middle Triassic of the Isfjorden area in Spitsbergen, Svalbard." References: Roberts, A.J.; Engelschiøn, V.S.; Hurum, J.H. (2022). "First three-dimensional skull of the Middle Triassic mixosaurid ichthyosaur Phalarodon fraasi from Svalbard, Norway". Acta Palaeontologica Polonica 67 (1): 51–62. DOI:https://doi.org/10.4202/app.00915.2021.