Trias

The shoulder girdle of the holotype of the Triassic ichthyosaur Toretocnemus (originally Leptocheirus, also Merriamia) zitteli. This image is derived from plate 21 in Merriam (1903), done by an uncredited artist. The arrangement of the individual figures has been slightly modified from the original. Original description: Leptocheirus zitteli n. gen. and sp. Figures reproduced natural size from the type specimen. Fig. 1.—Clavicles (cl) and probable interelavicle (Ic and Ic')- The interclavicle has been separated into two fragments by a crack in the matrix. Fig. 2.—Inner side of the coracoids and the left scapula.

Forelimb and partial hindlimb of the holotype of the Triassic ichthyosaur Toretocnemus (originally Leptocheirus, also Merriamia) zitteli. This image is derived from plate 22 in Merriam (1903), done by an uncredited artist. Original description: Leptocheirus zitteli n. gen. and sp. Figures reproduced natural size from the type specimen. Fig. 1. — Superior side of left anterior limb. r, radius. Fig. 2. — Posterior limb. t, tibia.

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.

Illustration of some anterior caudal vertebrae of the Californian ichthyosaur Torteocnemus californicus (specimen UCMP 8100), from Merriam's 1908 monograph on American Triassic ichthyosaurs. This illustration appeared as figure 4 of plate 14; it has been modified to remove the stamp placed on top of it. While Merriam credits two illustrators as having produced artwork for this publication, it is not clear which of them created this image.

Life restoration of the Triassic ichthyosaur Qianichthyosaurus xingyiensis. References Motani, Ryosuke; Jiang, Da-yong; Tintori, Andrea; Ji, Cheng; Huang, Jian-dong (2017). "Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates". Proceedings of the Royal Society B 284 (1854): 20170241. DOI:10.1098/rspb.2017.0241.

Figure description from paper: "Figure 23: Early and Middle Triassic ichthyopterygian heads possessing longirostry. Simplified outlines of four different Early and Middle Triassic ichthyopterygian heads possessing a long and slender rostrum. Specimens are at the same scale. (A) Utatsusaurus hataii (UHR 30691, Motani, Minoura & Ando, 1998); (B) Grippia longirostris (PMU R445, Motani, 2000); (C) Mixosaurus cornalianus (BES SC 1000, Renesto et al., 2020); (D) Besanosaurus leptorhynchus (PIMUZ T 4847, this paper); (E) Cymbospondylus buchseri (PIMUZ T 4351, Sander, 1989). Scale bar represents 10 cm." References: Bindellini, G.; Wolniewicz, A.S.; Miedema, F.; Scheyer, T.M.; Dal Sasso, C. (2021). "Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: Taxonomic and palaeobiological implications". PeerJ 9: e11179. DOI:10.7717/peerj.11179.

Besanosaurus leptorhynchus referred specimen PIMUZ T 4376, preserved on the same slab as a specimen of the smaller Mixosaurus. Scale bar represents 50 cm (1.6 ft). Figure 3C of Bindellini et al. (2021). References: Bindellini, G.; Wolniewicz, A.S.; Miedema, F.; Scheyer, T.M.; Dal Sasso, C. (2021). "Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: Taxonomic and palaeobiological implications". PeerJ 9: e11179. DOI:10.7717/peerj.11179.

Modified version of figure 23 of Bindellini et al. (2021) showing just the ichthyosaurs from the Besano Formation: Besanosaurus leptorhynchus (A), Mixosaurus cornalianus (B), and Cymbospondylus buchseri (C). The original figure was uploaded unmodified here: File:Early to Middle Triassic Longirostrine Ichthyopterygians.png References: Bindellini, G.; Wolniewicz, A.S.; Miedema, F.; Scheyer, T.M.; Dal Sasso, C. (2021). "Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: Taxonomic and palaeobiological implications". PeerJ 9: e11179. DOI:10.7717/peerj.11179.

Utatsusaurus hataii, an Early Triassic Ichthyosaur from Japan, pencil drawing

Augustasaurus hagdorni, a pistosaur from the Middle Triassic of nevada. Digital.

Nothosaurus mirabilis, a Nothosaur from the Triassic of Europe, North Africa and Russia, pencil drawing

Nothosaurus mirabilis, a Nothosaur from the Triassic of Europe, North Africa and Russia, pencil drawing

Skull of the Middle Triassic North-American ichthyosaur Cymbospondylus petrinus, preserved in three dimensions. This specimen is cataloged under the number UCMP 9913. More information is available from the source link.

Skull of the Middle Triassic North-American ichthyosaur Cymbospondylus petrinus, preserved in three dimensions. This specimen is cataloged under the number UCMP 9913. More information is available from the source link.

Thalattosaurus alexandrae (left) and Nectosaurus halinus (right) of Late Triassic California

Holotype specimen (PIMUZ A/III 1274) of Prosantosaurus scheffoldi gen. et spec. nov. from the upper Prosanto Formation (Early Ladinian, Middle Triassic) of Ducanfurgga locality no. 4, southwest of Davos, Canton of Grisons, south-eastern Switzerland. A Nearly complete specimen as prepared in dorsal view. The posterior part of the tail was lost prior to burial. Both forearms are not visible but lie below the trunk region, pointing in an anteromedial direction (see Additional file 1: Fig. S3A). B Detail of skull and anterior neck region. C Outline sketch of skull sutures. D Detail of shoulder girdle (claviculae, scapulae) and anterior dorsal vertebrae and ribs. E Detail of right humerus. F Detail of posterior dorsal vertebrae and ribs, sacral vertebrae and ribs, and anterior caudal vertebrae and ribs. G Detail of left ilium and hindlimb. ar articular; as astragalus; bo basioccipital; cal calcaneus; cl clavicula; co coracoid; d dentary; en external naris; eo exoccipital; fe femur; fi fibula; fr frontal; hu humerus; il ilium; in internal naris; is ischium; j jugal; mx maxilla; na naris; o orbit; pa parietal; pl palatine; pmx premaxilla; pof postfrontal; po postorbital; prf prefrontal; pt pterygoid; pu pubis; q quadrate; qj quadratojugal; ti tibia; sacr sacral rib; sc scapula; so supraoccipital; sp splenial; sq squamosal; su surangular; utf upper temporal fenestra; v vomer