Ontogeny of the braincase in Stenopterygius (Reptilia, Ichthyosauria) from the Lower Jurassic of Germany

Figures & data

FIGURE 1. Stenopterygius basioccipitals in dorsal (A–E) and posterior (F–J) views in order of increasing ossification. A–E, anterior is toward the top of the page; interpretive drawings below the images. A, embryo S. quadriscissus, SMNS 80234; B, embryo S. quadriscissus, SMNS 54064; C, juvenile S. quadriscissus, SMNS 50003; D, juvenile S. quadriscissus, SMNS 81958; E, adult S. quadriscissus, SMNS 81961; F, embryo S. quadriscissus, SMNS 80234; G, embryo S. quadriscissus, SMNS 80234; H, juvenile Stenopterygius sp., SMNS 81806; I, juvenile S. quadriscissus, SMNS 80062; J, adult S. triscissus, SMNS 50187. Abbreviations: anp, anterior notochord pit; bop, basioccipital peg; exf, exoccipital facet; fmf, floor of the foramen magnum; opf, opisthotic facet.

FIGURE 2. Stenopterygius parabasisphenoids in dorsal (A–E) and ventral (F–J) views in order of increasing ossification. Anterior is toward the top of the page. Interpretive drawings below the images. A, embryo S. quadriscissus, SMNS 80234; B, embryo S. quadriscissus, SMNS 81961; C, embryo S. quadriscissus, SMNS 54064; D, juvenile S. quadriscissus, SMNS 54026; E, adult S. quadriscissus, SMNS 80234; F–G, embryo S. quadriscissus, SMNS 80234; H, juvenile S. quadriscissus, SMNS 81958; I, adult S. quadriscissus, SMNS 54062; J, adult S. quadriscissus, SMNS 50376. Abbreviations: bof, basioccipital facet; ds, dorsum sellae; icf, internal carotid foramen; icfg, ventral internal carotid foramen groove; ptf, pterygoid facet.

FIGURE 3. Stenopterygius quadrates in posteromedial view (A–E) and stapes in anterior (F, J), posterior (G, H), and ventral (I) views in order of increasing ossification. Quadrates are right quadrates except for B and E, which are mirrored left quadrates. Stapes are right stapes except I, which is a mirrored left stapes. For quadrates, interpretive drawings below the images. A, embryo S. quadriscissus, SMNS 80234; B, embryo S. quadriscissus, SMNS 54064; C, juvenile S. quadriscissus, SMNS 50003; D, juvenile S. quadriscissus, SMNS 54026; E, adult S. quadriscissus, SMNS 54062; F, embryo S. quadriscissus, SMNS 80234; G, embryo S. quadriscissus, SMNS 54064; H, juvenile S. quadriscissus, SMNS 51139; I, juvenile S. quadriscissus, SMNS 81958; J, adult S. quadriscissus, SMNS 54064. Abbreviations: ac, articular condyle; stf, stapedial facet.

FIGURE 4. Stenopterygius supraoccipitals in anterior view (A–E) and exoccipitals in medial view (F–J) in order of increasing ossification. Exoccipitals are all left exoccipitals except I and J, which are right exoccipitals mirrored. For supraoccipitals, interpretive drawings below the images. A, embryo S. quadriscissus, SMNS 80234; B, embryo S. quadriscissus, SMNS 81961; C, juvenile S. quadriscissus, SMNS 51139; D, juvenile S. quadriscissus, SMNS 81958; E, adult S. quadriscissus, SMNS 58881; F, embryo S. quadriscissus, SMNS 80234; G, embryo S. quadriscissus, SMNS 54062; H, juvenile S. quadriscissus, SMNS 51959; I, juvenile S. quadriscissus, SMNS 51551; J, adult S. triscissus, SMNS 96899. Abbreviation: ag, anterior groove.

FIGURE 5. Stenopterygius right opisthotics (B–E) and prootics (F–J) in posterior view in order of increasing ossification, and an embryonic opisthotic in medial view (A). Interpretive drawings below the images. Prootics G, H, J, and opisthotic C have missing bone, indicated by dashed lines in the interpretive drawings. The position of the dividing ridge on the prootic is likewise denoted by a dashed line. All opisthotics are right opisthotics except C and E, which are mirrored left opisthotics. A, embryo S. quadriscissus, SMNS 80234; B, juvenile Stenopterygius sp., SMNS 81806; C, juvenile S. quadriscissus, SMNS 50003; D, juvenile S. quadriscissus, SMNS 81958; E, adult S. triscissus, SMNS 14846; F, embryo S. quadriscissus, SMNS 80234; G, juvenile S. quadriscissus, SMNS 51139; H, juvenile Stenopterygius sp., SMNS 81806; I, juvenile S. quadriscissus, SMNS 51551; J, adult S. quadriscissus, SMNS 54062. Abbreviations: bof, basioccipital facet; dv, dividing ridge; hsc, impression of the horizontal semicircular canal; pop, paroccipital process; ppvsc, dorsal process of the opisthotic housing the posterior vertical semicircular canal; pvsc, impression of the posterior vertical semicircular canal; su, indentation of the sacculus or the utriculus.