Saurorhynchus brevirostris (Woodward 1895)
- Dataset
- Revision of Saurorhynchus (Actinopterygii: Saurichthyidae) from the Early Jurassic of England and Germany
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Chordata
- class
- Actinopterygii
- order
- Saurichthyiformes
- family
- Saurichthyidae
- genus
- Saurorhynchus
- species
- Saurorhynchus brevirostris
description
Figs 1 B, 2 A, 4 B – E, 6 A
diagnosis
Revised differential diagnosis The diagnosis is constructed based on the holotype and referred material housed at the NHMUK. This species can be differentiated from all other Saurorhynchus species by the following combination of characters: short, deep skull, overbite consistently present (overbite slight or absent in S. acutus); posterior dorsal skull roof deflected dorsally relative to the long axis of the skull (parallel in S. acutus); postorbital segment approximately equal in length to the depth of the lower jaw; anterior narial opening large and triangular in outline with the apex directed toward the mandible (narrow and elongate in S. acutus); foramen for the internal carotid and efferent pseudobranchial arteries positioned posterolaterally within the basisphenoid, exposing the large foramen of the ophthalmica magna artery on the anterolateral surface of the basisphenoid; posterior edge of the mandible weakly sinusoidal (strongly sinusoidal in S. acutus); angle between the posterior and ventral edges of the mandible less than 80 degrees; subnarial laniaries well-developed with acrodin caps directed lingually (subnarial laniaries absent and all acrodin caps straight in S. acutus); mandibular sensory canal closer to the dorsal than ventral edge of the posterior mandible. Opercle strongly wedge-shaped; lateral supracleithrum bearing prominent anterior process pierced by a foramen; pectoral radials well-ossified.
discussion
Remarks Here we restrict usage of S. brevirostris to material from the Lower Lias. The anterior tip of the holotype skull is missing, but in the largest referred specimen skull length (tip of rostrum to jaw joint) is 86 mm (Suppl. Table 1). Assuming similar proportions to S. hauffi sp. nov., fork length is estimated at up to 30 cm for S. brevirostris.
materials_examined
Material studied Holotype UNITED KINGDOM: Lyme Regis (NHMUK PV OR 40726) (Fig. 1 B). A skull with partial pectoral girdle preserved in lateral view. This specimen is probably from the Charmouth Mudstone Formation, Black Ven Mudstone Member, latest early Sinemurian to late Sinemurian (Forey et al. 2010).