Conotheca spp.
publication ID |
https://doi.org/ 10.4202/app.2012.0004 |
persistent identifier |
https://treatment.plazi.org/id/03C3891D-1534-C26A-FCC9-FD38CAA9F9EC |
treatment provided by |
Felipe |
scientific name |
Conotheca spp. |
status |
|
Fig. 28 View Fig .
Material.—Several phosphatised opercula with cardinal processes, including SMNH X 4630–4632, from sample K1-3B; uppermost Emyaksin Formation, Malaya Kuonamka; Calodiscus -Erbiella Zone, lower Botoman Stage. One operculum, SMNH X 4633, from sample 7/31.5; Emyaksin Formation, Bol’shaya Kuonamka; correlated with the Delgadella anabara Zone, Atdabanian Stage.
Remarks.—Circular opercula from sample K1-3B with two prominent cardinal processes, nearly perpendicular to the surface of the operculum ( Fig. 28A–C View Fig ). The processes diverge at ca. 30º. The inner surface has a smooth distal ridge at the margin, low rounded polygonal pattern in the middle and faint radial striation laterally. The margin thins out gradually. Conchs with circular cross-section are not found in sample K1-3B, but occur in the coeval sample 7/70 from Bol’shaya Kuonamka.
The operculum from sample 7/31.5 has weakly developed cardinal processes and radially oriented lateral folds of the circular distal ridge ( Fig. 28D View Fig ). The ridge slopes abruptly towards the margin of the operculum. Radial folds developed laterally on the distal ridge are reminiscent of those described as tubular clavicles ( Malinky and Skovsted 2004) in Conotheca australiensis Bengtson in Bengtson et al., 1990, of which the interior surface morphology is otherwise different. Several straight fragments of conchs with circular cross-section ( Fig. 27H View Fig ) co-occur with the operculum in sample 7/31.5.
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