Pseudozygopleuridae Knight 1930 ...
Family Pseudozygopleuridae Knight, 1930 gen. et sp. indet. (Fig. 12) Material. Three larval shells from LD-04 (NHMUK PI MG 1532–1534). Description. Teleoconch not observed. Protoconch is conical, elongate and composed of five whorls. The initial whorl is smooth and has a diameter of 0.08 mm. Collabr...
| Main Authors: | , , |
|---|---|
| Format: | Text |
| Language: | unknown |
| Published: |
Zenodo
2016
|
| Subjects: | |
| Online Access: | https://dx.doi.org/10.5281/zenodo.10903534 https://zenodo.org/doi/10.5281/zenodo.10903534 |
| Summary: | Family Pseudozygopleuridae Knight, 1930 gen. et sp. indet. (Fig. 12) Material. Three larval shells from LD-04 (NHMUK PI MG 1532–1534). Description. Teleoconch not observed. Protoconch is conical, elongate and composed of five whorls. The initial whorl is smooth and has a diameter of 0.08 mm. Collabral ornamentation is initiated on the second whorl, continues to the base of the protoconch, and consists of narrow costellae that intersect at or just below the mid-whorl. Costellae are sigmoidal: on the upper part of the whorls they are slightly curved and oriented at 40 Ǫ to the shell axis, and on the lower part of the whorls they are oriented at 200 Ǫ to the shell axis. Growth lines are visible as faint collabral ribs between, and perpendicular to, the costellae. Aperture is circular, with a small columellar fold. Four whorls are present in these specimens. Remarks. Hoare & Sturgeon (1978) showed that protoconchs of species of Pseudozygopleuridae are very similar, but can be readily differentiated from ... : Published as part of Foster, William J., Danise, Silvia & Twitchett, Richard J., 2017, A silicified Early Triassic marine assemblage from Svalbard, pp. 851-877 in Journal of Systematic Palaeontology 15 (10) on pages 867-868, DOI: 10.1080/14772019.2016.1245680, http://zenodo.org/record/10883052 ... |
|---|