Eucalyptocrinites sp. 2

Ausich, William I., Wilson, Mark A. & Vinn, Olev, 2012, Crinoids from the Silurian of Western Estonia, Acta Palaeontologica Polonica 57 (3), pp. 613-631 : 621-622

Eucalyptocrinites sp. 2

Fig. 3D .

Material.—TUG 1395−12, Mustjala Member, Janni Formation, Suuriku Cliff; TUG 1395−13, Ninanse Member, Janni Formation, Panga Cliff; TUG 1395−14, Ninase Member, Janni Formation, Suuriku Cliff; TUG 1395−15 and TUG 1395−16, Ninase Member, Janni Formation, Undva Cliff. All are from Saaremaa Island.

Description.—The calyx is large for the genus. It is probably low cone shaped, but the base of the calyx and plating from basals through radials are unknown. The normal interrays are in contact with the tegmen partition plates. The first interradial is decagonal, higher than wide. The second range of the normal interray has two plates that are sutured to the interradial tegmen partition plates. Fixed primibrachials are not known. The second secundibrachials are axillary as known, yielding four arms per ray. One fixed intrabrachial plate is sutured distally with the partition plate. The tegmen partition plates extend to the base of anal tube, are gently convex on upper tegmen surface, extend to full height of crown, and are higher than the arms. Two circlets of plates frame the anal opening, with the tube probably absent ( Fig. 3D 1 ). Distal partition plates expanded to nearly four times proximal width with broad, deep longitudinal groove ( Fig. 3D 2).

Free arms atomous, pinnulate. First three or four brachials are cuneate uniserial, then biserial distally. Arms do not reach the full extent of the partition plates.

Column unknown.

Discussion.—Three very large and one smaller, very incomplete specimens have significant distal widening of the partition plates. Further, the wide distal portion of the partition plates have a broad groove along the center. Calyx sculpturing is inferred to be smooth based on two specimens. Specimen TUG 1395−16 has the distinctive partition plates, but the calyx is badly beach−worn. It is possible that the inferred sculpturing of this specimen is erroneous. Specimen TUG 1395−15 has smooth plate sculpturing, and the distal partition plates are not visible. However, the medial portion of the partition plates are expanding consistent with this morphology. Based on illustrations in Angelin (1878), this morphology could match one of the following species: E. minor ( Angelin, 1878) , E. plebejus ( Angelin, 1878) , E. regularis (Hisinger, 1840) , or E. rigens ( Angelin, 1878) . The details of calyx shape are necessary to distinguish among these species, so this taxon is also left in open nomenclature.

Measurements.—TUG 1395−16: crown height, 60.0* (proximal calyx missing); calyx width, 35.0*. TUG 1395−12: armtegmen complex width, 30.5.

Geographic and stratigraphic range.—All occurrences of this taxon are from Saaremaa Island, Estonia, with new collections from the Ninase Member of the Jaani Formation at

http://dx.doi.org/10.4202/app.2010.0094

Suuriku Cliff and the Ninase Member of the Jaani Formation at Panga Cliff, Suuriku Cliff, and Undva Cliff. All of these occurrences are Wenlock, Silurian.

Figures

Fig. 3. Camerate crinoids from the Silurian of Estonia. A, B. Middle Äigu Beds, Kaugatuma Formation (Pridoli), Kaugatuma Cliff. A. Eucalyptocrinites tumidus sp. nov., GIT 405−243. A1, lateral view of crown, note modestly expanding partition plates; A2, basal view of calyx, note nodose calyx plates; A3, tegmen view of crown, note flat tegmen top. B. Calliocrinus sedgwickianus sp. nov., TUG 1395−8. Basal view of a portion of the basal and radial circlets, all circular pits are the trace fossil Oichnus. C. Eucalyptocrinites sp., GIT 405−238, Jaani Formation (Wenlock), Suuriku Cliff. Lateral view of calyx. D. Eucalyptocrinites sp. 2., TUG 1395−13, Ninase Member, Jaani Formation (Wenlock), Panga Cliff. D1, tegmen view of crown; D2, B−ray view of partial crown, note deep elongate groove on well−preserved partition plate. E. Periechocrinus longimanus (Angelin, 1878), GIT 405−4−1, Jaani Formation (Wenlock), Janni Cliff. Lateral view of partial calyx, calyx sutures very indistinct. F. Eucalyptocrinites sp. 1, TUG 1375−3, Jaani Formation (Wenlock), Undva Cliff. Lateral view of broken crown. G. Calliocrinus sp., TUG 1395−6, Ninase Member, Jaani Formation (Wenlock), Suuriku Cliff. Broadly bifurcating spine. H. Eucalyptocrinites sp. 1, TUG 1375−2, Jaani Formation (Wenlock), Undva Cliff. Lateral view of crown of juvenile. Scale bars 10 mm.

Fig. 1. Silurian stratigraphy of Estonia. The majority of the new fossil material is from the West−Estonian islands, represented in the middle of the chart of lithostratigraphic units (based on Hints 2008). D1, Lower Devonian; O, Ordovician; O3, Upper Ordovician.