Torvoneustes undetermined

Young, Mark T, Foffa, Davide, Steel, Lorna & Etches, Steve, 2020, Macroevolutionary trends in the genus Torvoneustes (Crocodylomorpha: Metriorhynchidae) and discovery of a giant specimen from the Late Jurassic of Kimmeridge, UK, Zoological Journal of the Linnean Society 189 (2), pp. 483-493 : 487

TORVONEUSTES SP.

( FIG. 4 )

Specimens

O U M N H J.5 0 0 6 1, O U M N H J. 5 0 0 7 9–J. 5 0 0 8 5: incomplete isolated tooth crowns and roots.

Locality Shotover Hill, Oxfordshire, England, UK.

Horizon and age

Unknown horizon from the Kimmeridge Clay Formation. The deposits from this locality are almost entirely Early Tithonian in age, with the only Kimmeridgian horizon being the Pictonia baylei Sub-Boreal ammonite Zone (earliest Kimmeridgian) ( Cox, 2001: fig. 2.52). Most likely Lower Tithonian, Upper Jurassic.

are poorly preserved ( Wilkinson et al., 2008), and the holotype of T. coryphaeus is damaged in this region ( Young et al., 2013a). Between the tuberosities is a deep fossa, within which is the foramen for the medial pharyngeal tube that forms part of the median pharyngeal sinus system.

Description

Overall, these tooth crowns ( Fig. 4 ) are exceptions, similar to those of Torvoneustes carpenteri (see: Andrade et al., 2010; Young et al., 2013b), such that if they originated from the type locality, they would be assigned to T. carpenteri . The tooth crowns have a caniniform morphology and are single-cusped, conical with little labiolingual compression and are poorly curved lingually ( Fig. 4 ). However, looking at the crown and root, there is a noticeable lingual curvature (e.g. Fig. 4F ). The apices of the teeth are broken and/ or rounded, with no evidence of the natural apex preserved. Overall, the teeth retain their labiolingual width along most of their apicobasal length.

All the tooth crowns lack a constriction at the crown– root junction, although the boundary is evident due to the change in colour and texture. They also lack cingula (a ridge at the base of the crown) and accessory cusps/ denticles. The are no apicobasal troughs or flutings (see: Foffa et al., 2017, 2018). Moreover, the teeth lack the apicobasal facets on the labial surfaces, and the ‘laminar’ crown cross-sections seen in Geosaurus and Ieldraan (e.g. Young & Andrade, 2009; Andrade et al., 2010; Foffa et al., 2017, 2018). The teeth also lack the ‘carinal flanges’ and carinal (mesiodistal) macrowear seen in Dakosaurus ( Young et al., 2012a, b, 2015). The weak ‘carinal flanges’, which are preeminent at the mid-crown, and strong distal curvature of the mesial margin, which are diagnostic for Plesiosuchina, are also not present (see: Young et al., 2012a; Chiarenza et al., 2015).

All tooth crowns preserve mesial and distal carinae, but there are no split or supernumerary ones. In the apical region, the superficial enamel ornamentation

Figures

Figure 4. Torvoneustes sp. teeth, OUMNH J.50085 (A, D, G), J.50082 (B, E, H), J.50083 (C, F, I). Scale bar = 5 cm.