Heliobatis radians Marsh, 1877

DE CARVALHO, MARCELO R., MAISEY, JOHN G. & GRANDE, LANCE, 2004, Freshwater Stingrays Of The Green River Formation Of Wyoming (Early Eocene), With The Description Of A New Genus And Species And An Analysis Of Its Phylogenetic Relationships (Chondrichthyes: Myliobatiformes), Bulletin of the American Museum of Natural History 2004 (284), pp. 1-136 : 72

† Heliobatis radians Marsh, 1877 Figures 26B , 28–30 , table 4

† Heliobatis radians Marsh, 1877 (p. 256; original description, not illustrated); Grande, 1980, 1984 (pp. 24–30, figs. II.3–II.5, II.7c; description, photographs); Stevens and Last, 1994 (p. 61; photograph); Frickhinger, 1995 (p. 212; photograph, brief account); Long, 1995 (p. 87; photograph). † Xiphotrygon acutidens Cope, 1879 (p. 333; original description, not illustrated); Cope (1884; further description, illustrated). Dasyatis sp. : Haseman, 1912 (pp. 98–99). † Palaeodasybatis discus Fowler, 1947 (pp. 14– 15; original description, not illustrated); Grande, 1980, 1984 (p. 24, fig, II.5; first published photograph of type specimen, reported lost); Spamer et al., 1995 (p. 83; type­catalog, specimen confirmed as missing). † Dasyatis radians: Cappetta, 1987 (p. 163; transferal without comment of † H. radians Marsh, 1877 to Dasyatis Rafinesque, 1810 ). DESCRIPTION: As for genus. MATERIALS: Holotype: YPM 528, missing tail region (figured in Grande, 1984: 30, fig. II.7c; reproduced here as fig. 30A). Other specimens examined: AMNH P 856, male, exposed in ventral view, with tip of tail missing (ca. 370 mm TL, 210 mm DL; Twin Creek); AMNH P 857, female, exposed in ventral view (Newberry coll.); AMNH P 2474, probably female, exposed in ventral view, with tail tip posterior to stings missing (ca. 210 mm DL); AMNH P 2475, appears to be exposed in dorsal view; AMNH P 2985, female, exposed in ventral view, with left side of disc and tail just posterior to base not preserved; AMNH P 4345, adult male, exposed in ventral view (ca. 410 mm TL, 200 mm DL; Twin Creek); AMNH P 7828, adult male (illustrated in Schaeffer and Mangus, 1965), exposed in ventral (?) view; AMNH P 9873, adult male, with distal tip of tail missing, exposed in ventral view (ca. 400 mm TL, 230 mm DL); AMNH P 9874, teeth only; AMNH P 19665, subadult female, exposed in dorsal (?) view, from F­2 (fig. 28); ANSP 8344 (holotype of † Palaeodasybatis discus Fowler, 1947 , apparently lost, photograph in Grande, 1984: 27, fig. II.5; reproduced here as fig. 30B); DMNH 1530 (no further data); FMNH PF 2020, adult male, exposed in ventral view, from F­1 (fig. 29); FMNH PF 6947, female, exposed in dorsal view, from F­1; FMNH PF 10283 (tentatively identified), adult male, exposed in dorsal view, from Thompson Ranch (F­2); FMNH PF 25009, adult male, exposed in ventral view, from F­2 (specimen on exhibit); SMMP 77.27.1; SMMP 83.2.4; UW 11577; ZMB 1981.0 (adult male, F­2). Other referred material (not examined): UW 12309 (figured in McGrew and Casilliano, 1975).

STRATIGRAPHIC HORIZON: Fossil Butte Member of the Green River Formation, Ypresian stage (corresponding to the North American Wasatchian stage) of the late early Eocene epoch (some 52 million years before present).

ETYMOLOGY: The trivial name radians is derived from radius, Latin for ‘‘spoke’’, referring to the radial disposition of the pectoral fin rays. Gender feminine.

Figures

Fig. 26. Posterior tail region and caudal stings of specimens of †Asterotrygon, n. gen. (A, C, and D) and †Heliobatis (B). Note individual vertebrae continuing posteriorly beyond caudal stings to distal extremity of tail. A. FMNH PF 14097 (entire specimen in fig. 9). B. AMNH P 19665 (specimen in fig. 28). C. FMNH PF 12914 (reversed; specimen in fig. 6). D. FMNH PF 14098 (reversed; specimen in fig. 8). Anterior to bottom.

Fig. 28. †Heliobatis radians, AMNH P 19665, approximately 255 mm TL subadult (?) female, dorsally exposed (from F­2 locality). Anterior to top.

Fig. 29. †Heliobatis radians, FMNH PF 2020, approximately 463 mm TL adult male (terminal cartilages of claspers indicated by arrowhead), ventrally exposed (from F­1 locality). Anterior to top.

Fig. 30. †Heliobatis radians. A. Holotype of †Heliobatis radians Marsh, 1877 (YPM 528); note that tail region posterior to disc is missing. B. Holotype of †Palaeodasybatis discus Fowler, 1947 (ANSP 8344), length given as 345 mm TL in original description, but specimen missing distal tip of tail; note that radials of disc and pelvic fins are painted over. This specimen has recently been reported as missing (Spamer et al., 1995: 83). Anterior to top.