Calocyclas bandyca (Mato and Theyer)

Lychnocanoma bandyca Mato and Theyer, 1980, p.225, pl.1, figs.1-6

Calocyclas bandyca (Mato and Theyer), Sanfilippo and Riedel in Saunders et al., 1985, p.411, pl.5, figs.1,5-6

DESCRIPTION

Cephalis subhemispherical with a few, randomly arranged, small, irregular pores; apical spine lacking. Thorax campanulate with relatively large, longitudinally arranged hexagonal frames. Irregular, laminar lattice extends from distal thorax on well-preserved specimens. Very fine, randomly arranged distal pores. Three sturdy, prominent, cylindrical to conical, straight to slightly curved feet extend from thorax (Mato and Theyer, 1980).

DIMENSIONS

Based on 15 specimens. Overall length 310-470 m; of cephalis 20-30 m, of thorax 100-120 m, of feet 190-340 m; greatest width of cephalis 20-40 m, of thorax 120-140 m (Mato and Theyer, 1980).

Length (excluding horn) 290-470 m; of thorax 100-120 m; maximum width of thorax 105-140 m, width of aperture 50-70 m (Lychnocanoma bandyca in Sanfilippo et al., 1985).

DISTINGUISHING CHARACTERS

C. bandyca is distinguished from other species by its three (rarely four to five) subcylindrical, sturdy feet, and distinctive inflated thorax with longitudinally arranged pores in hexagonal frames. Occurring stratigraphically earlier (Podocyrtis mitra Zone) and through the Thyrsocyrtis bromia Zone together with Calocyclas bandyca are forms (of the Sethochytris babylonis group) with rather similar morphology. S. babylonis does not have an inflated thorax, the aperture is very restricted and the conical feet are long, very slender, never sturdy as those of Calocyclas bandyca (Lychnocanoma bandyca in Sanfilippo et al., 1985).

VARIABILITY

This two-segmented form varies little during its short stratigraphic range. The three, sturdy, cylindrical to conical feet vary somewhat in length, and in being straight or slightly curved. In some specimens, remnants of a delicate lattice extend from the distal margin of the thorax. Rare specimens with four or five feet are found near the beginning of its range (Lychnocanoma bandyca in Sanfilippo et al., 1985).

DISTRIBUTION

C. bandyca is found in moderate abundance in tropical localities of late late Eocene age. Its morphotypic first appearance marks the base of the Calocyclas bandyca Zone and it becomes extinct approximately at the upper limit of the same zone.

PHYLOGENY

C. bandyca evolved from Calocyclas turris via intermediate morphotypes in which the lamellar feet are fewer in number, long, and tending to be cylindrical proximally, joined about mid-length by a band of irregular lattice-work, which in some specimens extends upwards to join the thorax (Sanfilippo and Riedel in Saunders et al., 1985).

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