Saurostomus Agassiz, 1843

Genus Saurostomus Agassiz, 1843

Specimen MNHNL n° TU987a-b: Saurostomus esocinus Agassiz, 1843 and Loligosepiinae indet ( Fig. 5 View Fig ).

1999a Pachycormiforme aff. Saurostomus ; Delsate: fig. 16.

Locality Bascharage, collected by D. Watrinelle; ‘Schistes bitumineux’ formation, Serpentinum Chronozone.

Dimensions Preserved length of the fish 250 mm. Length of the opercle ca. 86 mm. In absence of further data, we use the opercle length; 86 mm × 9.5 = 817 mm, 86 mm × 19 = 1634 mm. Preserved length of the gladius: 50 mm.

Identification of the fish Left side of the fish preserving the articulated skull (cranial length 25 cm but the anterior region of the skull is damaged), the partial abdominal flank, and the partially preserved left pectoral fin. Te large opercular (dimensions: around 70 mm long axis) has a shield shape typical for Saurostomus (see Wenz, 1967: fig. 65), different from the triangular opercular of Pachycormus . Specimen TU987 is fully conformed to Cooper and Maxwell (2022) describing Saurostomus esocinus , and this specimen is part of the specimens they examined.

Identification and position of the gladius Te small, partially preserved gladius can be attributed to the Loligosepiinae owing to its extended hyperbolar zone (Fuchs & Weis, 2008). Its position is axial, in the antero-posterior axis of the fish, contacting the posterior border of the dorsal postcleithrum, and supposedly in esophageal position (esophagolite sensu Hunt & Lucas, 2012, consumulite in a broader sense).