Strobilodus sp.

Weryński, Łukasz, Błażejowski, Błażej & Kędzierski, Mariusz, 2023, A comparison of teeth in Tithonian, Late Jurassic, predatory actinopterygian fishes from Owadów-Brzezinki Lägerstatte and its palaeoecological implications, Acta Palaeontologica Polonica 68 (3), pp. 493-512 : 497-498

Strobilodus sp.

Fig. 2D .

Material.—Right dentary, ZPAL P.16./O-B/2 from Titho - nian, Upper Jurassic Kcynia Formation, Corbulomima Limestone (Unit III), Owadów-Brzezinki, Poland.

Description.—The study material consists of an incomplete right dentary bone, with preserved medial and partially preserved posterior section, with nine intact teeth. This bone measures 59 mm in the anteroposterior plane, 11 mm in the dorsoventral plane and 6 mm in the labiolingual plane. Its shape can generally be characterized as elongated and moderately gracile. In the anterior region, the bone is rectangular, while in the medial plane it is slightly curved dorsally. The robustness of the bone gradually decreases in the ventral direction. There is a prominent indentation along the ventral margin of the bone in the central region, identified as ventral grove housing sensory canal. The whole bone texture is rather rough and compact. Two teeth are missing from the alveoli of the described specimen ( Fig. 2D ).

The teeth of the specimen can be characterized as conical, with a thick basal part and with a diameter that drastically decreases at the mid-crown. In the mid-crown and apical parts, the shape is much more gracile and elongated. In the apical plane, the cross section can be characterized as rounded with slight labiolingual compression, characterized by carinae present from the mid crown to the apex, while the basal cross section is rather round. The length of the teeth varies slightly in the described dentary, with larger and more robust teeth located more anteriorly and the teeth are also better preserved in this part of the bone. Generally, the teeth can be described as roughly homodont in form and are characterized by a symmetrical shape, along with slight lingual curvature. The intact teeth studied herein have an average ratio of apicobasal height/mesiodistal length of 2.29 ( Table 1).

Remarks.—The relatively narrow and anteriorly tapering dentary; robust teeth with conical acrodin caps. This specimen was first described by Błażejowski et al. (2012) as dentary, belonging to the carnivorous Caturus sp. , and was later redescribed as left maxilla (Błażejowski et al. 2015). In current light we consider this specimen to belong to the Strobilodus sp. , based on the latest López-Arbarello and Ebert (2023) study and interpret this specimen as dentary.

Figures

Fig. 2. Studied specimens of actinopterygian fishes from Tithonian, Upper Jurassic Kcynia Formation, Corbulomima Limestone (Unit III), Owadów- Brzezinki, Poland. A–C. Loose teeth of Caturoidea indet. A. ZPAL P. 16/O-B/FT1. B. ZPAL P. 16/O-B/FT2. C. ZPAL P. 16/O-B/FT3. D. Caturoid Strobilodus sp., ZPAL P. 16/O-B/2, right dentary in lateral view. E. Pachycormid Orthocormus teyleri Lambers, 1988, ZPAL P. 16/O-B/3, left dentary (E1) and right dentary (E2) in lateral view. Dashed white lines indicate thin-sectioning plane; white arrows indicate which teeth were sampled for thin-section- ing (TS), black arrows indicate which samples were chosen for SEM analysis.