Ammonicrinus wanneri Springer, 1926

Bohatý, Jan, 2011, Revision of the flexible crinoid genus Ammonicrinus and a new hypothesis on its life mode, Acta Palaeontologica Polonica 56 (3), pp. 615-639 : 623-625

Ammonicrinus wanneri Springer, 1926

Figs. 2A, C , 9A–J , 15B .

pars 1926 Ammonicrinus wanneri Springer, 1926: 22–25 , pl. 6: 4−4b, only.

non 1926 Ammonicrinus wanneri Springer, 1926 : pl. 6: 5−5b = A. leunisseni sp. nov.

non 1926 Ammonicrinus wanneri Springer, 1926 : pl. 6: 6 = A. cf. sulcatus .

1938a Ammonicrinus wanneri ; Wolburg 1938a: pl. 18: 9.

non 1938a Ammonicrinus wanneri ; Wolburg 1938a: pl. 18: 10 = A. leunisseni sp. nov.

non 1952 Ammonicrinus wanneri ; Ubaghs 1952: 210, fig. 2, pl. 1: 1–7, pl. 2: 1–7 = A. jankei sp. nov.

non 1978 Ammonicrinus wanneri ; Ubaghs 1978: T78, fig. 57: 6, 7 = A. doliiformis , 8 = A. jankei sp. nov.

pars 1978 Ammonicrinus wanneri ; Moore 1978: T787, fig. 526: 5a–c, only.

non 1978 Ammonicrinus wanneri ; Moore 1978: T787, fig. 526: 5d–e = A. leunisseni sp. nov.

pars 2003 Ammonicrinus wanneri ; Webster 2003: GSA−webpage, A. wanneri Springer 1926 , pl. 6: 4−4b, only.

Holotype: USNM−S2115 ( Springer 1926: pl. 6: 4−4b, only) ( Fig. 2A, C ;

also see colour photos of Springer’s (1926) original on the webpagesearch of the USNM Department of Paleobiology collection). The assumed type locality is “Prüm”, within the Prüm Syncline , in the vicinity of locality 3 ( Eifel , Rhenish Massif, Rhineland Palatinate, Germany) ;

and the assumed stratigraphy is the uppermost Freilingen Formation

(upper Eifelian) or superposed Ahbach Formation (Eifelian/ Givetian threshold, Middle Devonian).

Material.— Type material ( Fig. 2A, C ) and new material nos.

GIK−2133–2142 ( Fig. 9A–J ). Description.— Ammonicrinus wanneri has fine tubercles on the cup ossicles ( Fig. 9B ). The stem mainly distinguished by the characteristic mesistele, composed of columnals with long and relative regularly developed LCEE that protrude nearly orthogonally from both sides of the narrow columnals, forming a narrow discoidal coiled proximal column in closed position ( Figs. 2A 2 , C, 9A ); mesistele composed of numerous columnals, which distally passes gradually into the dististele; several specimens have floating transitions between those individuals with none or one to several columnals with LCEE on the proximal−most, barrel−like dististele and the following mesistele; dististele either long and composed of numerous columnals (“encased runner−type”), short and composed of only few columnals, or nearly reduced (“settler−type”); distal−most dististele connected with a substrate−controlled holdfast composed of radices; axial canal pentalobate; mesistele sculptured by irregularly positioned or oriented ridges, which, characteristically, run parallel to each other on the external flanks of the columnals ( Fig. 9C, H ); no spine−tubercles on the stem.

doi:10.4202/app.2010.0020

Discussion.—The mesistele of A. wanneri is composed of regularly developed columnals with narrow and long LCEE that protrude nearly orthogonally from both sides of the columnals, resulting in narrow discoidal coiled proximal column in closed position; the radials are partly visible in lateral view of the coiled stem. In A. leunisseni sp. nov. the LCEE of the mesistele are shorter and interconnected with several columnals showing broadened extensions and combined with smaller, “regular” columnals that cover the cup completely; the radials are not visible in lateral view of the coiled stem. Additionally, the shape of the coiled stem is oblate spheroidal instead of discoidal. The columnals of the mesistele of A. wanneri are sculptured by tubercles, forming irregular ridges on the external flanks of the columnals; no spine−tubercles were observed. In contrast, A. leunisseni sp. nov. is a spined Ammonicrinus .

Stratigraphic and geographic range.—Upper Eifelian to Lower Givetian (Freilingen, Ahbach and Loogh formations) of the Eifel Synclines ( Germany).

Figures

Fig. 2. The first figures of Ammonicrinus from Springer (1926) and Krause (1927). A. Ammonicrinus wanneri Springer, 1926 (from Springer 1926: pl. 6: 4a, b). A1, view of the extetrnal flanks of the coiled mesistele; A2, coiled mesistele in lateral view. B. Ammonicrinus leunisseni sp. nov. (= “A. wanneri” in Springer 1926: pl. 6: 5, 5b). B1, view of the extetrnal flanks of the coiled mesistele; B2, coiled mesistele in lateral view. C. Photograph of the holotype of Ammonicrinus wanneri Springer, 1926, USNM−S2115; lateral view of coiled mesistele; connection between mesi− and dististele, dististele and attachment missing (see fracture surface at distal mesistele). D. Photograph of USNM−S2115, the Springer (1926) original of “Ammonicrinus wanneri” (= A. leunisseni sp. nov. herein); lateral view of coiled mesistele; connection between mesi− and dististele, dististele and attachment missing (see fracture surface at distal mesistele). E. Ammonicrinus doliiformis Wolburg, 1938a (for 1937) (= “A. wanneri” in Krause 1927: pl. 8: 4, 2). E1, view of the extetrnal flanks of the coiled mesistele; E2, coiled mesistele in lateral view. A–D from the Middle Devonian, Eifel Limestone; Prüm, Eifel, Germany (Springer 1926: 25); E from the Middle Devonian of Sötenich, Eifel (Krause 1927: 456). A, B, E not to scale; C, D scale bars 10 mm.

Fig. 9. Lecanocrinid Ammonicrinus species. A–J. Ammonicrinus wanneri Springer, 1926. A–I. From the Eifel (locality 3, Appendix 1), Germany, Lower Givetian (Middle Devonian). J. From the Eifel (locality 7, Appendix 1), Germany, Lower Givetian (Middle Devonian). A. Lateral view of a partly preserved specimen (GIK−2133) with coiled mesistele. B. Lateral view, respectively view of external columnal flanks of the coiled mesistele of a partly preserved specimen (GIK−2134) with one preserved, postulated cup ossicle (arrow). C. View of external columnal flanks of the mesistele of a partly preserved specimen (GIK−2135). D. Lateral view, respectively view of external columnal flanks of the coiled mesistele of a partly preserved specimen (GIK−2136), +

Fig. 15. Schematic sketches of different LCEE of the mesistele in uncoiled (above) and coiled positions (below), indicating evolution of perfecting the crown−encasing in coiled position by modifying the extensions form Emsian to Givetian. A. Lateral view of Ammonicrinus kerdreoletensis Le Menn and Jaouen, 2003, showing similar shaped columnals with very short LCEE; thus, the crown is laterally nearly unprotected in coiled position.B. Lateral view of Ammonicrinus wanneri Springer, 1926, with lengthened LCEE of the similar shaped columnals, which lattice−like guarded the crown in coiled position. C. Lateral view of Ammonicrinus sulcatus Kongiel, 1958, showing smaller columnals of the mesistele, which are interconnected with longer ones and afford lateral density of the coiled stem. D. Lateral view of Ammonicrinus doliiformis Wolburg, 1938a (for 1937), showing regularly or irregularly arranged columnals with longer and shorter LCEE, which were interconnected with several columnals showing broadened convex and concave extensions that could interlock in coiled position.