Formation · Jurassic
Holzmaden (Posidonia Shale)
Early Jurassic unit, Baden-Württemberg
The Posidonia Shale at Holzmaden and Ohmden is the Early Jurassic black shale that preserves ichthyosaurs with skin outlines, the giant crinoid colonies of Seirocrinus on driftwood, Dactylioceras ammonites by the thousand and pyritised fish. Dactylioceras and small crinoid slabs are affordable; Stenopterygius skeletons and Seirocrinus colonies sell for tens or hundreds of thousands. The shale is soft and prepared with air scribes, and many commercial slabs are backed and edged with filler, so ask what proportion of a large piece is original.
| Country | Germany |
|---|---|
| Region | Baden-Württemberg |
| Age | Toarcian, Early Jurassic |
| Age range | ~183–180 Ma |
| PBDB collections | 33 collections, 83 occurrences· Paleobiology Database |
Collecting and legality
Baden-Württemberg's Kulturdenkmal rules protect scientifically significant Holzmaden finds, and the state museum has right of first refusal on important vertebrates; the Kromer and Fischer quarries at Ohmden run public collecting areas whose finds are yours. Prepared ichthyosaurs with export from Germany are legal but should carry a dealer invoice.
Lithology and setting
Bituminous black shale with thin limestone beds, laid down in an oxygen-starved epicontinental sea during the Toarcian oceanic anoxic event.
Commonly recorded taxa (PBDB)
Genera most often recorded from this unit in the Paleobiology Database (first 200 occurrences): Saurorhynchus (10), Saurostomus (8), Dactylioceras (6), Parainoceramya (5), Eleganticeras (4), Meleagrinella (4), Harpoceras (3), Coelodiscus (2), Hildoceras (2), Lytoceras (2), Meleagrinella (Praemeleagrinella) (2), Phylloceras (2), Rasnitsyneura (2), Tiltoniceras (2), Acanthorhina (1).
Source: Paleobiology Database
Collecting rules
Elsewhere
Cite this article
Stratum Study. "Holzmaden (Posidonia Shale)" (Formation). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/formations/holzmaden-posidonia-shale. Accessed 2026-09-20.
@misc{stratum-holzmaden-posidonia-shale,
title = {Holzmaden (Posidonia Shale)},
author = {{Stratum Study}},
howpublished = {\url{https://stratum.black/study/formations/holzmaden-posidonia-shale}},
year = {2026},
note = {Formation article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, pbdb, commons. Accessed 2026-09-20.}
} Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.