Stenosaurus elegans, Sachs & Young & Abel & Mallison, 2021

Sachs, Sven, Young, Mark T., Abel, Pascal & Mallison, Heinrich, 2021, A new species of Cricosaurus (Thalattosuchia, Metriorhynchidae) based upon a remarkably well-preserved skeleton from the Upper Jurassic of Germany, Palaeontologia Electronica (a 24) 24 (2), pp. 1-28 : 22

Cricosaurus elegans (Wagner, 1852) Wagner, 1858

v* 1852 Stenosaurus elegans sp. nov. – Wagner,

p. 98, pl. 14. [sic] v 1858 Cricosaurus elegans (Wagner) gen. et comb. nov. – Wagner, p. 22, Taf. 14, figure 1-2. v 1888 a Metriorhynchus elegans (Wagner) comb.

nov. – Lydekker, p. 98. v 1973 Cricosaurus elegans (Wagner) – Steel, p.

42. v 2009 Cricosaurus elegans (Wagner) – Young and Andrade, p. 557, figure 6. v 2010 Cricosaurus elegans (Wagner) – Young et al., p. 804. v 2019 Cricosaurus elegans (Wagner) – Sachs et al., p. 1, figure 9b. Holotype. SNSB-BSPG AS I 504: complete cranium preserved in lithographic limestone ( Figure 9C ). Type locality. Daiting, Bavaria, Germany. Type formation. Mörnsheim Formation Type horizon. Subplanites moernsheimensis Subzone , Hybonoticeras hybonotum Tethyian ammonite Zone, lower Tithonian, Upper Jurassic. Etymology. ‘Slender ring lizard’. Referred specimens. SNSB-BSPG 1977 XIX 38: skull preserved in lithographic limestone (from Daiting; Mörnsheim Formation).

The referral of these two specimens from the Altmühltal Formation was made by Lydekker (1888) and is here considered tentative: NHMUK PV OR 37006: poorly preserved rostrum in lithographic limestone (from Solnhofen); NHMUK PV OR 43005: poorly preserved skull and vertebral column in lithographic limestone (from Eichstätt). Geological range. Upper Jurassic. Hybonoticeras hybonotum Tethyian ammonite Zone, lower Tithonian. Emended diagnosis. A member of Cricosaurus with the following unique combination of characters: dentition lacking conspicuous enamel ornamentation; tooth crowns in the premaxilla, maxilla and dentary show distinct labiolingual compression (shared with C. albersdoerferi BMMS-BK 1-2, C. bambergensis NKMB-P-Watt14/274 and C. suevicus GPIT-PV-31381, SMNS 9808, SMNS 90513); lack of pronounced, or regular shallow, reception pits on the lateral margins of the middle maxilla and dentary (shared with C. medius SNSB-BSPG AS VI 2 and C. suevicus GPIT-PV-31381, SMNS 9808, SMNS 90513).

Cricosaurus elegans shares the following synapomorphy with C. albersdoerferi (BMMS-BK 1-2), C. medius (SNSB-BSPG AS VI 2) and C. suevicus (GPIT-PV-31381, SMNS 9808, SMNS 90513): 1) the maxillary tooth row terminates either anterior to, or approximately level to the anterior-margin of the orbits.

Note. Unfortunately, the C. elegans holotype, and all early Tithonian specimens, are only known from cranial material (or associated cervical vertebrae). Therefore, the dorsal neural spine and tail autapomorphies of the other taxa cannot be compared against the early Tithonian material. We herein refrain from synonymising C. elegans with C. medius and C. suevicus until early Tithonian Cricosaurus postcranial anatomy is: 1) discovered, and 2) better understood. As, the surprising variation in late Kimmeridgian Cricosaurus specimens means we cannot automatically assume conspecificity (the newly described species C. rauhuti from the early Tithonian helps reinforce our reticence).

Figures

FIGURE 9. Comparison of crania of Late Jurassic Cricosaurus specimens from southern Germany. (A) BMMS-BK 1-2, holotype of Cricosaurus albersdoerferi sp. nov.; (B) NKMB-P-Watt14/274, holotype of Cricosaurus bambergensis; (C) SNSB-BSPG AS I 504, holotype of Cricosaurus elegans; (D) SMNS 9808, lectotype of Cricosaurus suevicus; (E) GPIT-PV-31381, referred specimen of Cricosaurus suevicus and (F) SMNS 7322, referred specimen of Cricosaurus suevicus. Scale bars equal 50 mm.