Thalattorhynchus austriacus, Schultz, 1987

Gracia, Carlos De, Correa-Metrio, Alex, Carvalho, Monica, Velez-Juarbe, Jorge, P ̆ rik, Tom ́ a ̆ s, , Carlos Jarami & Kri, nd Jurgen, 2022, Towards a unifying systematic scheme of fossil and living billfishes (Teleostei, Istiophoridae), Journal of Systematic Palaeontology (2091959) 20 (1), pp. 1-36 : 22

Genus and species indet. ‘ Thalattorhynchus austriacus ’ (Supplemental material Fig. S6)

1987 † Thalattorhynchus austriacus Schultz : 151–152, abb. 3, 4, 5/78, pl. 1, figs 1, 11, fig. 17.

1998 † Thalattorhynchus austriacus Schultz : 128, pl. 58, fig. 6 ( Schultz 1998).

2013 † Thalattorhynchus austriacus Schultz : 373/2, pl. 70, fig. 4a–d ( Schultz 2013).

Material. NHMW 1986/109, a distal section of rostrum of 79.30 mm long.

Occurrence. Middle Miocene (~16.3–12.8 Ma), Badenian Paratethys stage, Marzer Kogel, SE Mattersburg, Burgenland, Austria.

Remarks. The specimen is a slender distal rostral fragment of 79.3 mm length that represents the 0.5 L region (Supplemental material Fig. S6A). The distal tip is pointed and preserves the distal end of the grooves that articulate with the prenasals in dorsal view (Supplemental material Fig. S6A). In lateral view, the rostrum is straight with a slightly upward curvature (Supplemental material Fig. S6A). The distal fragment is entirely covered by denticles ventrally along its entirely preserved length and in lateral view the zone covered by denticles is extended about 3 / 4 of the total height (Supplemental material Fig. S6A). The denticles, which are housed in alveoli, are conical and range from 0.79 to 1.19 mm in height (Supplemental material Fig. S6A, B). Those placed on the lateral edges are larger than those positioned in the middle section (Supplemental material Fig. S6A).

In cross-section the rostrum is oval (W2 = 17.51 mm, D2 = 13.72 mm) and the suture of the premaxillae is visible but secondarily filled with gypsum (Supplemental material Fig. S6B). It has only one internal canal that is circular in shape and placed ventrally at about 1.75 mm of the diameter (Supplemental material Fig. S6B). This specimen was described as Thalattorhynchus austriacus representing a xiphiorhynchid billfish based on having a single longitudinal canal as autapomorphy ( Schultz 1987). However, the preserved rostrum has a morphology that corresponds to members of the family Istiophoridae possessing slender rostra (Supplemental material Fig. S6A, B). The evidence shows that some extant istiophorid specimens may lack one internal canal in the rostrum as an anomalous condition and with the preserved section, it is not possible to detect additional autapomorphies to correctly assign this specimen to any genus or species ( Fierstine 1990; Fierstine & Voigt 1996). However, we nevertheless include this specimen here to highlight the importance of this specimen because demostrates the existence of slender rostra istiophorids during the middle Miocene.