Dailyatia sp.

Wrona, Ryszard, 2004, Cambrian microfossils from glacial erratics of King George Island, Antarctica, Acta Palaeontologica Polonica 49 (1), pp. 13-56 : 30-34

Dailyatia sp.

Fig. 10 .

Material.— Two (one broken) isolated sclerites, ZPAL V. VI/ 31 S2, 8, from erratic boulder Me33 .

Description.—Gently curved, comparatively large sclerite, with prominent apex and shape ranging from pyramide ( Fig. 10 ) to cornute. The wall is phosphatic, densely lamellar. The external sculpture consists of equally spaced sharp ridges without reticulate micro−ornament between ridges ( Fig. 10D ). Among the three known Dailyatia sclerite forms (e.g., Evans and Rowell 1990), two were recognized in the present collection: type B, subtriangular to subovate in cross−section, pyramidal sellate shape with longitudinal folds and posterior face saddle−like; and type C, triangular to crescentic in cross−section,

Fig. 8. A–E. Dailyatia ajax Bischoff. A. Dextral juvenile? sclerite of form C, ZPAL V.VI/15U4, erratic Me66; A 1, oblique proximal view, stereo−pair; Ą A 2, lateral inner view; A 3, detail of epithelial pattern on apex, in oblique lateral view, stereo−pair; A 4, detail of apex in adapical view; A 5, detail of apex in oblique lateral view. B. Dextral sclerite, form C, ZPAL V.V/39S9, erratic Me66, in lateral view. C. Siculate sinistral sclerite, form C, ZPAL V.VI/39S27, erratic Me66; C 1, inner lateral view, stereo−pair; C 2, outer lateral edge of sclerite; C 3, outer lateral view; C 4, detail of edge at distal part, in lateral view;

C 5, detail showing epithelial polygons; C 6, distal part, opening cavity. D. Sellate sclerite, form C, ZPAL V.VI/39S26, erratic Me66, in anterior side view.

E. Opening cavity of dextral sclerite, form C, ZPAL V.VI/39S34, erratic Me66. F. Isolated sclerite of tommotiide indet., ZPAL V.VI/39S6, erratic Me66;

F 1, proximal outer view, stereo−pair; F 2, surface ornamentation.

Fig. 11. Dailyatia ajax Bischoff. A. Sinistral adult? sclerite, form C, ZPAL V.VI/29S7, erratic Me66; A 1, oblique anterior view, stereo−pair; A 2, oblique lat− Ą eral view; A 3, left lateral view; A 4, right lateral view; A 5, detail of growth ribs and inter−rib areas; A 6, detail of surface, showing ornamentation based on epithelial polygonal pattern. B. Dextral sellate sclerite, form C, ZPAL V.VI/29S3, erratic Me66; B 1, oblique view; B 2, detail of apex; B 3, lateral view, showing distorttion of growth ribs. C. Sclerite, form C, ZPAL V.VI/39S19, erratic Me66, in oblique view, stereo−pair. D. Asymmetric sclerite, form B, ZPAL V.VI/32S2, erratic Me33; D 1, adapical view; D 2, oblique anterior view; D 3, outer lateral view; D 4, apex, in lateral view, showing epithelial polygons; D 5, the same in oblique anterior view, stereo−pair; D 6, ornamentation in detail of D 1.

pyramidal in shape with slight curvature and without longitudinal folds and torsion ( Fig. 10 ).

Remarks.—The sculpture, especially the ribbing pattern, seems to change with increase in size, being denser in larger (more adult) specimens ( Fig. 10D ). The sclerites are somewhat similar to those of D. bradocki Evans and Rowell , known only from the Shackleton Limestone, southern Churchill Mountains, Antarctica ( Evans and Rowell 1990).

Occurrence.—Allochthonous Early Cambrian (Botomian) boulders (Me33), King George Island, Antarctica.

Tommotiide indet.

Fig. 8F.

Material.—One isolated sclerite, ZPAL V.VI/103S11, from erratic boulder Me33.

Description.—Minute sclerite, flattened triangular in shape, with somewhat reduced one side, broad apex, and small radial furrow on the left side. External sculpture consists of growth ridges with superimposed closely spaced longitudinal ribs radially oriented. Sclerite wall has phosphatic composition and lamellar growth. This broadly conical sclerite may represent a sclerite of Daylatia in its initial stage of growth. A radial furrow on the sclerite’s left side gives the basal margin a sinuous and slightly sellate appearance resembling, in shape and external surface sculpture, the Camenella sclerite ( Rozanov and Missarzhevsky 1966; Rozanov et al. 1969).

Occurrence.—Allochthonous Early Cambrian (Botomian) boulders (Me33), King George Island, Antarctica.

Figures

Fig. 10. Sclerite of Dailyatia sp., ZPAL V.VI/31S2, erratic Me33. A. Oblique right lateral (anterior) view of asymmetrical triangular sclerite, type C. B. Oblique apical view. C. Oblique left lateral view. D. Enlargement of ornamentation showing growth ribs.