Cricosaurus albersdoerferi, 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 : 5

Cricosaurus albersdoerferi sp. nov.

Figures 1 , 3-7

zoobank.org/ 53679A64-7EC2-49D2-A222-D3103FDDDD84

Holotype. BMMS-BK 1-2 , almost complete articulated skeleton ( Figure 1 ).

Type locality. Rygol quarry, Painten, Bavaria, Germany.

Type formation. Arnstorf Member, Torleite Formation.

Type horizon. Lithacoceras ulmense Subzone , Hybonoticeras beckeri Tethyian ammonite Zone, upper Kimmeridgian, Upper Jurassic.

Geological provenance. Upper Jurassic. Lithacoceras ulmense Subzone , Hybonoticeras beckeri Tethyian ammonite Zone, upper Kimmeridgian.

Etymology. The species epithet albersdoerferi honours palaeontologist Raimund Albersdörfer for making the specimen available to science.

Diagnosis. A member of Cricosaurus with the following unique combination of characters (proposed autapomorphic characters are indicated by an asterisk *): bicarinate dentition, lacking conspicuous enamel ornamentation; tooth crowns in premaxilla, maxilla and dentary distinctly labiolingually compressed (shared with C. bambergensis , C. elegans , and C. suevicus ); presence of pronounced reception pits for dentary tooth crowns on the lateral margins of the anterior and mid-maxilla (shared with C. bambergensis ); presence of pronounced reception pits on the lateral margins of the middle dentary*; morphology of the tail displacement unit: the distal-most six preflexural vertebrae are very strongly posteriorly inclined and lie on top of the prezygapophyses of the adjacent vertebra with their posterior margins; the distal-most preflexural vertebra lacks the rod-like neural spine present in C. suevicus (SMNS 9808).

Cricosaurus albersdoerferi and C. suevicus share the following synapomorphies: (1) dorsal vertebrae neural spines are rectangular in lateral view; (2) almost all dorsal neural spines have flat dorsal margins; (3) the distal-most preflexural vertebra has a dorsoventrally deep hemapophysis, with a midline flange (i.e., unlike the rod-shaped hemapophysis as in C. bambergensis NKMB-PWatt14/274 and Rhacheosaurus gracilis NHMUK PV R 3948 – see Sachs et al., 2019); (4) the five-six proximal-most flexural caudal vertebrae have strongly anteriorly oriented neural spines (more prominently than in C. bambergensis NKMB-PWatt14/274, R. gracilis NHMUK PV R 3948 and Thalattosuchus superciliosus GPIT-PV-31379); and (5) the flexural hemapophyses contact one another along their posteroventral-anterodorsal margins (not along their posterior-anterior margins as in C. bambergensis NKMB-P-Watt14/274, R. gracilis NHMUK PV R 3948 and T. superciliosus GPIT-PV-31379).

Figures

FIGURE 1. Cricosaurus albersdoerferi sp. nov. (BMMS-BK 1-2) holotype, late Kimmeridgian of Painten (Southern Ger- many). Skeleton in lateral view. Scale bar equals 200 mm.

FIGURE 3. Cricosaurus albersdoerferi sp. nov. (BMMS-BK 1-2) holotype, late Kimmeridgian of Painten (Southern Germany). Skull in lateral view with illustration of the preserved elements. Abbreviations: an, angular; art, articular; cor, coronoid; d, dentary; en, external naris; fr, frontal; hy, hyoid; jug, jugal; lac, lacrimal; mx, maxilla; ns, nasal; pmx, premaxilla; po, postorbital; pof, preorbital fenestra; prf, prefrontal;?qu, possible quadrate; sa, surangular; sdg, surangulodentary groove; sp, splenial;?sq, squamosal or squamosal-postorbital fragment. Scale bar equals 50 mm.

FIGURE 4. Cricosaurus albersdoerferi sp. nov. (BMMS- BK 1-2) holotype, late Kimmeridgian of Painten (Southern Germany). Close-ups of the dentition (A) and scleral ring (B). Scale bars equal 10 mm.

FIGURE 5. Cricosaurus albersdoerferi sp. nov. (BMMS-BK 1-2) holotype, late Kimmeridgian of Painten (Southern Germany). Cervical (A); dorsal (B) and sacral vertebrae (C) in lateral view. Abbreviations: ans, axis neural spine; axp, axis postzygapophysis; axr, axis rib; cr, cervical rib; dia, diapophysis; ns, neural spine; pat, postzygapophysis of atlas; pp, parapophysis; sr, sacral rib; sv, sacral vertebra. Scale bars equal 30 mm.

FIGURE 6. Cricosaurus albersdoerferi sp. nov. (BMMS-BK 1-2) holotype, late Kimmeridgian of Painten (Southern Germany). Caudal vertebrae in lateral view. (A) proximal caudals, (B) distal caudal series and tail bend. Abbreviations: ap, anterior process; ffc, first flexural caudal vertebra; hp, hemapophysis; hs, hemapophyseal lobe; ns, neural spine. Scale bars equal 50 mm.

FIGURE 7. Cricosaurus albersdoerferi sp. nov. (BMMS-BK 1-2) holotype, late Kimmeridgian of Painten (Southern Germany). Limbs and girdle elements. (A) front limbs and pectoral girdle, (B) hind limbs and pelvis. Abbreviations: ast, astragalus; cal, calcaneum; co, coracoid; dt, distal tarsal; fe, femur; fi, fibula; h, humerus; il, ilium; mc, metacarpal; mt, metatarsal; ph, phalanx; pub, pubis; r, radius; re, radiale; sc, scapula; ti, tibia; u, ulna. Scale bars equal 50 mm.