Conotheca spp.

Kouchinsky, Artem, Bengtson, Stefan, Clausen, Sébastien & Vendrasco, Michael J., 2015, An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia, Acta Palaeontologica Polonica 60 (2), pp. 421-512 : 445

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

 

Conotheca spp.

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.

Kingdom

Animalia

Phylum

Mollusca

Family

Coleolidae

Genus

Conotheca

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