Cretasquatina americana, Maisey & Ehret & Denton, 2020

Maisey, John G., Ehret, Dana J. & Denton, John S. S., 2020, A new genus of Late Cretaceous angel shark (Elasmobranchii; Squatinidae), with comments on squatinid phylogeny, American Museum Novitates 2020 (3954), pp. 1-1 : 1-

Cretasquatina americana , new species

DIAGNOSIS: As for genus.

ETYMOLOGY: From the Latinized version of the name Amerigo .

HOLOTYPE: ALMNH 2792 ( figs. 2–4 , 7 , 10 , 11 ), from the Early Campanian Mooreville Chalk (unnamed member below the Arcola Limestone Member), Harrell Station Paleontological Site , Marion Junction , Dallas County, Alabama: an associated series of six anterior vertebrae ( ALMNH 2792 -C; fig. 2 ), an almost complete left palatoquadrate approximately 125 mm long ( ALMNH 2792 -A), most of a ceratohyal approximately 120 mm long ( ALMNH 2792 -B), a small fragment of cartilage from the braincase, possibly part of the postorbital process ( ALMNH 2792 -D), plus numerous smaller indeterminate fragments of tessellated calcified cartilage (hereafter abbreviated to TCC).

REFERRED MATERIAL: ALMNH 1040 ( fig. 8 ), including: almost complete right palatoquadrate approx. 143 mm long ( ALMNH 1040-A); anterior part of left palatoquadrate ( ALMNH 1040-B); two fragments of expanded arcualia from the first vertebra ( ALMNH 1040-C); incomplete second vertebra ( ALMNH 1040-D); vertebral centrum of uncertain position ( ALMNH 1040-E.); heavily abraded vertebral centrum showing fine concentric rings ( ALMNH 1040-F); numerous indeterminate fragments of calcified cartilage.

Figures

FIG. 2. Cretasquatina americana, gen. nov., sp. nov. Holotype, ALMNH 2792-C, six associated vertebrae forming the anterior vertebral complex: A, dorsal view; B, ventral view; C, anterior views of centra 1–6; D, posterior views of centra 1–6.

FIG. 3. Cretasquatina americana. Holotype, ALMNH 2792-C, first vertebra: A, dorsal view; B, ventral view; C, anterior view; D, posterior view. Note large size of individual tesserae.

FIG. 4. Cretasquatina americana. Holotype, ALMNH 2792-C, computerized tomography images of slices through first vertebra: A, horizontal section through middle of centrum just above median process; B, slightly higher horizontal section clipping anterior part of spinal canal; C, midsagittal section through vertebral centrum. Note the extremely large size of individual tesserae, especially rows of “voussoir” tesserae along margins between adjacent surfaces.

FIG. 7. ALMNH 2792-A, almost complete left palatoquadrate, referred here to Cretasquatina americana: A, lateral view, anterior to left; B, mesial view, anterior to right; C, dorsal view, anterior to left; D, ventral view, anterior to left. Note extremely large cartilage tesserae (some with zigzag intertesseral contacts), especially in the center of the lateral surface of the palatoquadrate main bar in A.

FIG. 10. ALMNH 2792-B, three views of ceratohyal referred here to Cretasquatina americana. Anterior to right in A and C, to left in B. Again, note the extremely coarse texture of tesserae.

FIG. 11. ALMNH 2792-D, fragment of braincase, possibly part of the postorbital process. Small white stars in B mark a series of voussoir tesserae lining the outer margin of a foramen.

FIG. 8. Additional palatoquadrates referred here to Cretasquatina americana: A–C, ALMNH 1040-A, almost complete right palatoquadrate approximately 143 mm long. A, lateral view, anterior to right; B, mesial view, anterior to left; C, dorsal view, anterior to left; D, E, ALMNH 1040-B, anterior part of left palatoquadrate matching 1040-A in size and representing its antimere (the two were collected together).