Ausich et al.—Disparid and hybocrinid crinoids from the Brechin Lagerstätte
primibrachials much larger than those in other rays; typically first primibrachial axillary in A, B, and D rays; third to fourth
primibrachial axillary in C and E rays; the second to fourth secundibrachial is axillary, and as many as six bifurcations in an arm. In contrast, A. incurvus has an outflaring radial circlet; C- and E-ray primibrachials approximately the same size as those in other rays; the first or second primibrachial axillary in A, B, D, and E rays, more primibrachials in C ray; third or sixth secundibrachial axillary; and at least four bifurcations in an arm. ?Anomalocrinus antiquus has an more vertically oriented radial circlet, one partial arm and primibrachials in two other rays preserved, brachials higher than wide, the first primibrachial is axillary, and an axillary in the secundibrachitaxis (if present) higher than the third secundibrachial.
Anomalocrinus astrictus new species
urn:lsid:
zoobank.org:act:E2DD9F5A-4DA4-425A- ABCD-FD699373CD44 Figures 5.3, 5.4, 6, 7
Type specimens.—Holotype,UMMP74661; paratypes,UMMP 74662 and 74663.
Diagnosis.—Anomalocrinus with radial circlet more vertically oriented, angustary radial facets (except C ray), brachials higher than wide, the first or the fourth primibrachial axillary (most commonly first), second to fourth secundibrachial axillary, and as many as six bifurcations in an arm.
Occurrence.—This new species is known only from the Brechin Lagerstätte in the Bobcaygeon-Verulam contact zone at the Carden Quarry (UMMP 74662) and the LaFarge Quarry (UMMP 74663) (Ordovician; Katian).
Description.—Crown medium-sized, subcylindrical. Aboral cup low bowl shaped, ~1.5 times wider than high; plates gently convex, plate sculpture smooth (Fig. 6.1). Basal circlet ~35% of aboral cup height; basal plates five,
pentagonal, ~1.5 times wider than high. Radial circlet more vertically directed, ~65% of aboral cup height; radial plates five, A, B, and D radial plates simple, 2.0 times wider than high; C and E radial plates compound (Figs. 5.3, 6.3, 7); infer- and superradial plates together larger than one simple radial plate; C infer- and superradial plates narrower and more equidimen- sional than simple radial plates; C inferradial plate pentagonal, as wide as high; C superradial plate octagonal, mostly above the distal extent of other radial plates, tapering distally, maximum width greater than height. A, B, D, and E radial facets angustary to peneplenary, ~60−80% of distal radial plate width; C radial facet plenary (Fig. 5.4), details of facet surface unknown. First anal plate above aboral cup, sutured beneath to upper
shoulders of C superradial and D radial plates (Fig. 7). Arms branching isotomously as many as six times.
Nonaxillary brachials rectilinear uniserial, convex with straight or concave sides; progressively higher-order brachitaxes with more exaggerated concave sides (Fig. 6.1); all axillaries with concave sides (except for some first primibrachials that are axillary, very small, sublenticular, and 1.25 times wider than high). A, B, andDrays typically with first primibrachial axillary;
859
C and E rays with three or four primibrachials that are much larger than those of other rays. Nonaxillary brachials becoming progressively higher than wide from proximal to distal. Beginning in secundibrachitaxis, gracile ramules branching at irregular intervals (ramules fromeither every successive brachial or separated by nonaxillary brachials). Ramulars up to four times higher than wide, rectilinear uniserial with concave sides. Column heteromorphic (Fig. 6.2), subcircular to multi-
lobate. Periphery of many internodals with a beaded appear- ance. Proxistele columnals up to 22 times wider than high; mesistele columnals organized as N3231323, ranging from ~30 to 7.5 times wider than high.
Etymology.—The new species name is derived from astrictus (L.) meaning drawn, together, tight, narrow, close; and it refers to the medial constriction of the width of the brachials.
Materials.—UMMP 74661−74663.
Measurements.—UMMP 74661, holotype: CrH, 61.1*; ACH, 8.8; ACW, 17.6; CoH, 18.0*. UMMP 74662, paratype: CrH, 56.0; ACH, 12.0; ACW, 21.2; CoH, 80.5*. UMMP 74663, paratype: CrH, 58.0*; ACH, 8.0*; ACW, 20*; CoH, 90*.
Remarks.—See species comparisons in remarks for genus. Order Calceocrinida Ausich, 1998
Family Calceocrinidae Meek and Worthen, 1869 Genus Cremacrinus Ulrich, 1886
Type species.—Cremacrinus punctatus Ulrich, 1886.
Other species.—Cremacrinus arctus Sardeson, 1928; C. articulosus (Billings, 1859); C. billingsianus (Ringueberg, 1889); C. crossmani Brower and Strimple, 1983; C. decatur Springer, 1926; C. drummuckensis (Ramsbottom, 1961); C. forrestonensis (Kolata, 1975); C. furcillatus (Billings, 1887); C. gerki Brower and Strimple, 1983; C. guttenbergensis Kolata, 1975; C. inaequalis (Billings, 1859); C. kentuckiensis (Miller and Gurley, 1894); ?C. latus (Brower and Veinus, 1974); C. lucifer Bolton, 1970; C. ramifer (Brower, 1977); C. rugosus (Billings, 1887); C. tubuliferus Springer, 1926; and C. ulrichi Springer, 1926.
Occurrence.—Ordovician (Sandbian), Illinois, Iowa, Minne- sota, Oklahoma, and Wisconsin, USA; Katian, Illinois, Iowa, Kentucky, Minnesota, Tennessee, and Wisconsin, USA, Ontario, Canada, and Scotland; Silurian (Ludlow and Pridoli), Tennessee, USA.
Remarks.—Six species of Cremacrinus have been reported from the Ordovician in Ontario and Quebec: C. articulosus, C. billingsianus, C. furcillatus,C. inaequalis, C. lucifer, and C. rugosus. Wilson (1946) noted that both C. furcillatus and C. rugosus were known from single specimens that were lost. In addition, many additional species are known from the United States (Webster and Webster, 2013). The presence or absence of three characters can be used to quickly subdivide Cremacrinus into groups: (1) E-ray arm divided or atomous;
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