Paralcidia glabella
| Paralcidia glabella | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Jurassic (Upper Callovian ) | ||||||||||||
| 163.5 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Paralcidia glabella | ||||||||||||
| ( Leckenby , 1859) | ||||||||||||
Paralcidia glabella is a species of the ammonites (Ammonoidea) from the Jura . The animals had the typical involute, hardly sculpted shell of the genus Paralcidia and achieved a maximum shell diameter of 70 (macroconch) or 20 mm (microconch). The ammonites were found as a fossil in Europe . The species was first described in 1859 by John Leckenby .
features
Paralcidia glabella had an involute, compressed shell. The outer side of the inner windings was sharpened, while that of the living chamber was more rounded. The case was sculptural and had only weakly indicated, distant sickle ribs. As with all Paralcidia species, the mouth rim of the species was simply designed and had lateral apophyses ("ears"). The up to 20 mm large microconch was less involute than the maximum 70 mm large macroconch and had a winding cross section that was less triangular.
Stratigraphy and geographic distribution
Paralcidia glabella rarely occurs in layers from the upper callovium . In Great Britain the ammonite was found in the athleta and lamberti zone and is therefore a species of the outgoing Central Jurassic .
Taxonomy
The species was in 1859 by John Leckenby from Hackness rock member of the Oxford Clay as Ammonites glabella (based on a nearly complete Makroconchs Inventory number NHM 39562) first described .
swell
literature
- Kevin N. Page: Ammonites. In: David M. Martill, John D. Hudson (Eds.): Fossils from Ornatenton and Oxford Clay . A determination atlas. Goldschneck-Verlag, Korb 1994, ISBN 3-926129-17-4 , pp. 117-149.
- John Leckenby: On the Kelloway Rock of the Yorkshire Coast. In: Quarterly Journal of the Geological Society . Vol. 15, 1859, ISSN 0370-291X , pp. 4-15, doi : 10.1144 / GSL.JGS.1859.015.01-02.07 .