An ichthyosaur from the UK Triassic–Jurassic boundary: A second specimen of the leptonectid ichthyosaur Wahlisaurus massarae Lomax 2016

Abstract

The holotype of Wahlisaurus massarae is known only from a partial skull and postcranial skeleton from the Lower Jurassic, collected near Normanton on Soar, Nottinghamshire, UK. It is diagnosed relative to other ichthyosaurs on the basis of autapomorphies of the coracoid and a unique combination of characters. Here, we report a second specimen of W. massarae. The new specimen comprises a practically complete right coracoid that clearly shows the unique morphology of W. massarae. This specimen was collected in situ from a quarry in Somerset, from the base of the Blue Lias Formation, which corresponds to the Triassic-Jurassic boundary (uppermost Rhaetian or lowermost Hettangian), extending the geographic and stratigraphic range of the species. Furthermore, the coracoid of the new specimen is 20% anteroposteriorly longer than in the holotype, representing a larger individual. In light of preparation and the identification of additional fragments of the holotype, a redescription of the skull morphology of the holotype, as well as comparison with the skull roof of Leptonectes tenuirostris, is included.

A giant Late Triassic ichthyosaur from the UK and a reinterpretation of the Aust Cliff ‘dinosaurian’ bones

“…However, the specimen was found loose on the beach and the stratigraphy of the specimen is not well constrained. It is possible that the specimen is actually from the Westbury Mudstone Formation [ 13 ], which would be more consistent with the occurrences of the Lilstock and Aust specimens.…”

“…Shastasaurids appeared in the Ladinian (Middle Triassic) and persisted to at least the Rhaetian (Late Triassic), with their highest taxonomic diversity occurring in the Carnian (early Late Triassic) [ 5 , 12 ]. The shastasaurids might even have survived into the early Jurassic [ 6 ], although this has been questioned [ 13 ]. The last of the shastasaurid taxa that can be assigned to genera are Shonisaurus sikanniensis , and, probably Himalayasaurus tibetensis , both of which occurred in the Norian (middle to late Late Triassic).…”

A new specimen ofPalvennia hoybergeti: implications for cranial and pectoral girdle anatomy in ophthalmosaurid ichthyosaurs

“…Individual or intrageneric variation is known from taxa with many specimens such as Stenopterygius and Ichthyosaurus , for instance in the shape and size of the anterior notch ( Johnson, 1979 ; Lomax & Massare, 2017 ; Lomax, Massare & Mistry, 2017 ). However, the PCA, discriminant analysis and the MANOVA test show that there is a phylogenetic signal in the coracoid shape, as argued by Lomax (2017) and Lomax, Evans & Carpenter (2018) . The phylogenetic character presently in use to cover the phylogenetic variation in coracoids is the relationship between length and width ( Fischer et al, 2016 ).…”

Peer Review #2 of "Refining the marine reptile turnover at the Early–Middle Jurassic transition (v0.2)"

“…The posterior apical centra are strongly compressed laterally, suggesting the presence of a lunate tailfin; although is the angle of the tailbent is unknown. The coracoid (Figure 3 A-B) possesses a wide anterior notch, unlike in leptonectids (Huene, 1951;Maisch & Matzke, 2000;Lomax, 2016;Lomax, Evans & Carpenter, 2018). The presence of a posterolateral emargination, typical of Ichthyosaurus, Protoichthyosaurus, and Temnodontosaurus (Home, 1819;Godefroit, 1993a;Lomax & Massare, 2015;Lomax, Porro & Larkin, 2019) cannot be assessed because the coracoid is incomplete (Figure 3A).…”