Pleuroceras spinatum (Bruguière 1789)

Taxonomy

Ammonite

Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Ammonitida
Family: Amaltieidae
Genus: Pleuroceras
Species: Pleuroceras spinatum
Author Citation Bruguière 1789

Geological Time Scale

Eon: Phanerozoic
Era: Mesozoic
Period: Jurassic
Sub Period: None
Epoch: Early
International Age: Late Pliensbachian

Stratigraphy

Amaltheenton-Formation

Biostratigraphy

Spinatum Zone
hawskerense subzone
Spinatum Bank

Provenance

Collector: Jakob Hatz
Acquired by: Purchase/Trade

Dimensions

Diameter: 6 cm

Location

Altdorf
Bavaria
Germany

• a369 & a1148
• altdorf
• amaltheento formation
• bavaria
• germany
• pleuroceras spinatum
• spinatum zone
• upper pliensbachian

Comments

The first three photos show an extremely well-preserved specimen of this species which was gifted to me by an aquaintance. The last three show an accumulation of strongly pyritized ones from the clay pit at Buttenheim in Bavaria, the largest of which has a diameter of 5cm. This is the index fossil for the spinatum zone and also for the spinatum subzone, an informal designation in Germany.

The clay pit at Buttenheim is world-reknowned for its upper Pliensbachian ammonite fauna. It is one of, when not the best site worldwide for studying the breadth of variation and development of form through time, particularly of the various species of the genus Pleuroceras. Zones, subzones and horizons are all easily accessible and layed out like the pages of a book here.

This species looks quite similar to P. solare, but is relatively easily distinguishable upon closer study. The extremely strong ribs rise to a point slightly above the keel, whereas the somewhat weaker ones of P.solare lie a little below its keel. The whorls of P.spinatum are also somewhat wider than those of P.solare.

 

Old German Chronostratigraphy: Lias (Schwarzjura) delta

Literature: Simonsen,S. et al (2012): Die Tongrube Buttenheim, 2. überarbeitete Auflage, Verlag Der Steinkern