Hecticoceras pseudopunctatum
| Hecticoceras pseudopunctatum | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temporal occurrence | ||||||||||||
| Middle Jurassic (Upper Callovian ) | ||||||||||||
| 163.5 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Hecticoceras pseudopunctatum | ||||||||||||
| ( Lahusen , 1883) | ||||||||||||
Hecticoceras pseudopunctatum is a species of the ammonites (Ammonoidea) from the Jura . As macroconches, the animals had a wide-naveled casing with flattened flanks and a simple mouth, and as microconches they had muzzle ears. The maximum diameter of the species was around 10 cm. The known distribution extended over the area of the northern Tethys tributaries from today's Great Britain to the Urals. The species was first described in 1889 by Joseph Lahusen .
features
At the macroconch, Hecticoceras pseudopunctatum had a slightly wide-naveled casing with a high-mouthed convolutions cross-section and flattened flanks. The primary ribs of the macroconch give way to sharp, curved secondary ribs in the area of the central turns, which swell slightly on the outer half of the shell. From a diameter of 30 to 40 mm, the primary ribs usually disappear completely. In the case of macro conches, the mouth edge is simply designed. At 100 mm, they were probably fully grown. The microconch of the species was more naveled and had muzzle ears. Its sickle ribs disappear on the inner half of the flanks or they form elongated, thickened rib ridges.
Stratigraphy and geographic distribution
Hecticoceras pseudopunctatum occurs in the proniae and spinosum subzones of the European Jurassic, i.e. the top two sections of the athleta zone. This makes the ammonite a species of the early Upper Calcium . The distribution extended over the area of today's Great Britain to the Urals .
Taxonomy and systematics
The species was in 1889 by Joseph Lahusen from the Jurassic of today's Ryazan as " Harpoceras pseudopuntatum " first described . A pseudonym is " Hecticoceras nodosum " J. Sowerby , 1818 . The species is placed within Hecticoceras in the subgenus Orbignyceras , which is characterized by flattened macroconches.
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.