A well-preserved specimen of Stenopterygius quadriscissus (Reptilia, Ichthyosauria) from the Early Jurassic (Toarcian) of Yorkshire, UK and new insights into species delineation in the genus Author Biot, Timothée https://orcid.org/0009-0000-4506-9528 Département Sciences de la Terre, University of Lille, Cité Scientifique, Bât. SN 5, Avenue Paul Langevin - 59655 Villeneuve d'Ascq Cedex, France & Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany Author Lomax, Dean R. 0000-0001-6985-3966 Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Bristol, UK & Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK Author Miedema, Feiko 0000-0002-6888-3546 Naturhistoriskmuseum, Universitetet i Oslo, Kabelgaten 40, 0581 Oslo, Norway Author Maxwell, Erin E. 0000-0002-6032-6251 Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany text Fossil Record 2026 2026-05-08 29 1 185 210 journal article 315129 10.3897/fr.29.185733 7235ae08-1241-44fd-ac1f-e1d57463dc14 ECA6AD31-3060-4FB4-9BEC-A1437C3DA07F

Table 1. Skeletal measurements of SMNS 55110 (in mm).

	Measurement (mm)
Total length	1458
Lower jaw (length)	337.1
Premaxilla (length)	208.4
Snout (length)	252.6
Scleral ring (length)	67.9
Scleral ring (depth)	74
Aperture (length)	30
Total caudal length	827.5
Tailstock length	583.9
Postflexural length	243.6
Fore-limb length	L: 157.7 / R: 156.4
Humerus length	L: 47.7 / R: 49.6
Humerus proximal width Humerus distal width	L: 20.6 / R: 26.8 L: 38.9 / R: 38.1
Radius (length)	L: 21 / R: 20
Radius (width)	L: 24 / R: 21
Ulna (length)	L: 21 / R: 19
Ulna (width)	L: 23 / R: 22
Radiale (length)	L: 18.5 / R: 15
Radiale (width)	L: 17.8 / R: 17
Ulnare (length)	L: 16.1 / R: 16
Ulnare (width)	L: 16.7 / R: 15.5
Radial facet of intermedium	L: 10.4 / R: 10.3
Ulnar facet of intermedium	L: 10.5 / R: 10.2