Furcaster
paleozoicus
The Devonian-aged Hunsrück Slate Lagerstätte
is one of the most famous soft-bodied fossil deposits. Hunsrück
fossils have been pyritized (replaced with pyrite/“fool’s
gold” - FeS2). They occur in a black slate matrix - the result
is beautiful brassy gold colored fossils on a black background. A diverse
biota has been described, including trilobites with preserved legs & gills,
crinoids, starfish & brittle stars, “worms”, molluscs, corals,
conulariids, sponges, cnidarians, land plants, “algae”, fish, plus
various unusual arthropods & echinoderms.
The Hunsrück Slate Lagerstätte occurs in the
Kaub Formation (Hunsrück Slate Group, lower Emsian Stage, upper Lower
Devonian) in the Budenbach area of western Germany.
Preparation of Hunsrück fossils is notoriously
difficult, and many of the pyritized fossils crumble to dust from pyrite
disease over many years. Recently, a “secret” air abrasion
method has been successfully used to prepare Hunsrück fossils, using an
abrasive grit composed of metallic iron powder mixed with potato starch.
Shown below is a pyritized, complete fossil brittle
star (ophiuroid) from the Hunsrück. All five arms are bent in the
same direction, indicating current direction before final burial. This is
a Furcaster paleozoicus brittle star, a species first described by
Bernhard Stürtz in 1886.
Classification: Animalia, Echinodermata, Asterozoa, Ophiuroidea,
Oegophiurida, Zeugophiurina, Furcasteridae
Furcaster paleozoicus Stürtz, 1886 (8.5 cm long) with current aligned
arms from the Hunsrück Lagerstätte (Lower Devonian) of western
Germany.
Furcaster paleozoicus Stürtz, 1886 (field of view ~4.0 cm across) from
the Hunsrück Lagerstätte (Lower Devonian) of western Germany.