Floating sea lilies
Crinoids, or sea lilies, are echinoderms related to starfish and sea urchins. Most fossil crinoids lived fixed to the seafloor on a stalk. The Moroccan species are different. Scyphocrinitids had a long stem that ended in a bulb-shaped float called a lobolith, and the animal is generally reconstructed hanging from it, drifting with its crown of arms below. Such a float is unusual among crinoids.
A 1992 monograph by Reimund Haude is the standard study of these buoy crinoids of the uppermost Silurian and lowermost Devonian[1]. Several lobolith types are known, including the specialized plate lobolith[2].
Age and localities
Scyphocrinitids thrived across the Silurian–Devonian boundary, about 419 million years ago, from the late Pridoli into the early Lochkovian. In North Africa they occur in limestone bands and nodular concretions within black, graptolite-bearing shales along the southern edge of the Anti-Atlas, in the Dra plain and in the Tafilalt near Erfoud, together with orthocones and bivalves. Slabs from these beds appear at fossil fairs worldwide, most labelled “Erfoud”[3].
Scyphocrinites or Marhoumacrinus?
Moroccan crinoids are almost always sold as Scyphocrinites elegans. That name is based on Bohemian material. In 1987 Prokop and Petr described a new genus and species, Marhoumacrinus legrandi, from the Marhouma section in Algeria. They noted that crinoids of this horizon had commonly been identified as Scyphocrinites species, including S. elegans, and listed plate loboliths from Hamar Laghdad in the Tafilalt among their material[2]. Without a detailed calyx study, the safest label is “scyphocrinitid crinoid”. We use the trade name with this note where relevant.
| Scientific name | Scyphocrinitid crinoids (traded as Scyphocrinites; North African material partly referred to Marhoumacrinus) |
|---|---|
| Geological age | Late Silurian (Pridoli) to Early Devonian (Lochkovian), about 419 million years |
| Formation | Limestone bands and concretions in Silurian–Devonian black shales of the Anti-Atlas |
| Locality in Morocco | Tafilalt near Erfoud (incl. Hamar Laghdad), Alnif area, southern Anti-Atlas |
| Typical size | Calyx and arms about 5–20 cm; plates from 15 cm to over 1 m; loboliths about 5–15 cm |
What you can buy
- Crinoid plates: a crinoid fossil plate is a slab with one or more crowns and stems, prepared in relief on dark limestone.
- Loboliths: the float bulbs, sold whole or cut and polished to show their internal chambers.
- Single calyxes: smaller crowns for collectors and education sets.
Restoration notes
Large plates are often reassembled from several fractured pieces of slab, and crowns can be repositioned or transplanted. That is not a problem when disclosed, but it changes the value. Ask whether each crown lies where it was found, and look for joins in the matrix and for matrix of a different color around a crown. We state on every listing whether a plate is natural, repaired or assembled.
Crinoid plates pair well with Orthoceras and Fossil Decor in a shop display. For large plates, ask about packing and freight through Request a Quote or apply for wholesale.
References
- Haude, R. (1992). Scyphocrinoiden, die Bojen-Seelilien im hohen Silur–tiefen Devon [Scyphocrinoids, the buoy crinoids in the uppermost Silurian–lowermost Devonian]. Palaeontographica Abteilung A 222(4–6): 141–187. schweizerbart.de (publisher record)
- Prokop, R.J. & Petr, V. (1987). Marhoumacrinus legrandi, gen. et sp. n. (Crinoidea, Camerata) from Upper Silurian – lowermost Devonian of Algeria. Sborník Národního muzea v Praze, Acta Musei Nationalis Pragae 43B(1): 1–14. publikace.nm.cz (PDF)
- Hess, H. (1999). Scyphocrinitids from the Silurian–Devonian boundary of Morocco. In: Hess, H., Ausich, W.I., Brett, C.E. & Simms, M.J. (eds), Fossil Crinoids, pp. 93–102. Cambridge University Press. doi:10.1017/CBO9780511626159.013
Frequently asked questions
What is a lobolith?
A lobolith is the bulb-shaped float at the end of a scyphocrinitid crinoid's stem. The animal is thought to have hung from it and drifted in the water. Such a float is unusual among crinoids. Loboliths are sold whole or cut and polished to show their internal structure.
How old are Moroccan crinoid plates?
They date from the Silurian–Devonian boundary, about 419 million years ago, from the late Pridoli to the early Lochkovian. They come from limestone bands and concretions in black shales of the Anti-Atlas, mainly around Erfoud and the Tafilalt, where they occur with orthocerid nautiloids and bivalves.
Are Moroccan crinoid plates assembled?
Some are. Large plates are often glued from several fractured pieces of slab, and crowns can be moved or transplanted for a better display. Natural plates exist and are worth more. Each of our listings states whether a plate is natural, repaired or assembled.