SilesianTriassic

Palaeobates angustissimus.

Middle Triassic, Lower Muschelkalk (Anisian), Gogolin Beds

Upper Silesia, Poland

Two specimens of lateral nad ?anterolateral teeth from the Triassic hybodont shark Palaeobates angustissimus. They were found in a single piece of limestone matrix, so I decided to describe them together.

LMK/28

The tooth’s crown is approximately 7mm long and 3mm wide, it and exhibits a labiolingual compression and curvature. It is characterized by an elongated, asymmetrical hexagonal shape with a slightly convex surface lacking cusps. While the root is either absent or obscured within the matrix, the crown surface displays fine, punctate ornamentation (dense pits). The size, shape, and ornamentation correspond to those of Palaeobates angustissimus.

Surface of the crown, particularly in its apical portion, shows signs of smoothing or polishing, possibly reflecting functional wear.

LMK/29

The crown is shorter (5mm, 2,7mm wide), more compact, and relatively higher. Ornamentation is well expressed, with a smooth area restricted to the apical region. The ornamentation is more reticulated than the purely pitted, extending toward the edges before disappearing—a morphology consistent with the descriptions of Palaeobates angustissimus.

While the crown shape might superficially resemble Acrodus lateralis, the well-preserved ornamentation is consistent with P. angustissimus. Unlike A. lateralis, which features fine striae converging toward the apical ridge, this specimen displays the reticular surface characteristic of Palaeobates.

The overall crown morphology — more compact and higher — may indicate a mesial or anterolateral tooth position.

References

• Böttcher, R. (2015). BÖTTCHER, R. (2015): 8. Fische des Lettenkeupers. – In: HAGDORN, H., SCHOCH, R. & SCHWEIGERT, G. (eds.): Der Lettenkeuper – Ein Fenster in die Zeit vor den Dinosauriern. – Palaeodiversity, Sonderband: 141–202. Palaeodiversity, Sonderband, 141–202.
• Chrząstek, A. (2008). Vertebrate remains from the Lower Muschelkalk of Raciborowice Górne (North-Sudetic Basin, SW Poland). Geological Quarterly, 52, 225–238.
• Geologische Landesanstalt von Elsass-Lothringen., & Elsass-Lothringen, G. L. von. (1891). Abhandlungen zur geologischen Specialkarte von Elsass-Lothringen: Bd.3 (1891) (s. 1–708). R. Schultz. https://www.biodiversitylibrary.org/item/192845
• Palaeontographica: Bd.1 (1851) (s. 1–460). (1846). Theodor Fischer. https://www.biodiversitylibrary.org/item/43708