692
Journal of Paleontology 92(4):681–712
octagonal, large central circular node, as high as wide, not in contact with tegmen, smaller than radials. Primanal heptagonal, slightly wider than high, slightly
smaller than adjacent radial plates, interrupts radial circlet, with large central circular node; three plates in second range; if third range present one or two plates. Fixed brachials with central elongate transverse node. First primibrachial wider than high; second primibrachial axillary; a
single, axillary secundibrachial; two to four (typically three) fixed tertibrachials. Tegmen medium inverted cone from arm openings to base
of anal tube, all plates with central circular nodes. Free arms 18–20, 2–4 arms in A ray; facets large, nearly
vertical. Proximal column circular with pentalobate lumen, other details not known.
Materials.—The holotype of A. steropes is UI X-840. Type material of junior synonyms include Actinocrinites gibbosus Troost (nomen nudum), Troost specimen USNM 39892; Actinocrinites? sayi Troost (nomen nudum), Troost specimen USNM 39899; B. springeranus, holotype, USNM S 3870. Specimens collected for this study include USNM 939904– USNM 939906.
Measurements.—See Supplemental Table 3.
Remarks.—Numerous specimens of Abatocrinus steropes are present in collections of the Fort Payne from the Lake Cumberland area. These specimens differ in relative degree of calyx size at the level of arm openings, as well as distortion of the entire theca through expansive silicification during diagenesis. Undistorted, smaller specimens have a much smaller diameter at the level of the arm openings. Additionally, these specimens may be preserved as an inner calcareous core of a partially silicified specimen (Fig. 5.6). The result of this style of preservation is a very subdued degree of plate sculpturing. In areas where the outer silicified surface is preserved, the plate sculpturing is consistent with other specimens. Most of the larger specimens are enlarged with expansive silicification that displaces thecal plating, yet retaining the relative positions of plates. Expansive silicification of Abatocrinus steropes specimens contrasts with Abatocrinus grandis
that
commonly has silica replacement of plates, but not expansive silicification. See the discussion of A. grandis for comparison of A.
steropes with other early Viséan species of Abatocrinus. Previous authors have regarded two of Troost’s nomina
nuda taxa to belong to Abatocrinus steropes: Actinocrinites gibbosus Troost, 1849 and Actinocrinites? sayi Troost, 1850b. Here, Batocrinus springeranus is also designated as a junior synonym of Abatocrinus steropes, which has a typical morphology for Abatocrinus steropes.
Genus Alloprosallocrinus Casseday and Lyon, 1862
Type species.—Alloprosallocrinus conicus Casseday and Lyon, 1862, by monotypy.
Diagnosis.—Calyx shape flat bowl or cone; basal concavity present, small or absent; calyx much lower than tegmen; calyx plates smooth to convex; no median ray ridges; plates commonly with indistinct sutures; basal plates low, in basal concavity, no proximal expansion; radial plates low; first primibrachial tetragonal or pentagonal (axillary); rays not lobate; regular interrays not in contact with tegmen; CD interray in contact with tegmen; tegmen high inverted conical; tegmen plates smooth or nodose; anal tube cylindrical; arm facets face outward (subvertical); and free arms 10–20, unbranched, not spatulate distally (from Ausich and Kammer, 2010).
Occurrence.—Alloprosallocrinus is only known from the early Viséan (late Osagean) of the central United States.
Alloprosallocrinus conicus Casseday and Lyon, 1862 Figure 6
1849 Conocrinites Leæ Troost, p. 419 (nomen nudum).
1849 Conocrinites tuberculosus Troost, p. 419 (nomen nudum).
1862 Alloprosallocrinus conicus Casseday and Lyon, p. 29. 1862 Alloprosallocrinus depressus Casseday and Lyon, p. 31.
1897 Alloprosallocrinus conicus Casseday and Lyon; Wachsmuth and Springer, p. 407, pl. 42, figs. 14a–c.
1958 Alloprosallocrinus conicus Casseday and Lyon; Lane, p. 127, pl. 9, figs. 11.
1964 Alloprosallocrinus conicus Casseday and Lyon; Van Sant, p. 110, pl. 7, figs. 2–4; figs. 17.5, 18, 37 (non fig. 11 as given).
1978 Alloprosallocrinus conicus Casseday and Lyon; N.G. Lane, p. T467, fig. 275.3a–c.
2013 Alloprosallocrinus conicus Casseday and Lyon; Webster and Webster, p. 800.
Complete synonymy list in Supplemental Data 2. Lectotype.—USNM S 783a. Diagnosis.—See genus diagnosis.
Occurrence.—Alloprosallocrinus conicus is a widespread, early Viséan crinoid species. The holotype of Alloprosallocrinus conicus was described from Clear Creek, Hardin County, Kentucky (Muldraugh Formation). The type specimens of junior synonyms, all presumably from the Fort Payne Formation, are from the following: Conocrinus leae and Conocrinus tuberculosus (nomina nuda) holotypes, Whites Creek Springs, Davidson Co., Tennessee; Alloprosallocrinus depressus holotype, Clear Creek, Hardin County, Kentucky; and Alloprosallocrinus gurleyi holotype, “Keokuk Group” Brown County, Kentucky (this must be a mistaken location). This species is now recognized from the following early
Viséan formations: (1) Muldraugh Member of the Borden Formation (Elizabethtown, Hardin County, Kentucky); (2) Fort Payne Formation in Kentucky (Clinton, Cumberland, Russell, and Wayne counties, Kentucky); in Tennessee atWhites Creek Springs (Davidson County), Clay County, Lawrence County (Krivicich et al., 2013, Localities 5 and 6), and Pickett County; and in Alabama
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