Trilobites of Gees,
last revised 01 December 2007 by S.M. Gon III Germany
Near Gerolstein, Eifel region, Rhine Valley, Rhenish Massif, Western Germany
Stratigraphy: Ahrdorf Formation, Flesten-Member
Age: Early Middle Devonian (Middle Eifelian), 398 - 392 mya
The site "Pelm-Salmer Weg" near the small village of Gees, in western
, is famous for fine Eifelian trilobites that have been found there over a 200 year period. The Trilobitenfelder (Trilobite Fields) there comprise the type stratum and locality for many classic trilobite species. The earliest trilobite described from the site dates back to 1825, when Heinrich Georg Bronn collected and described "Calymene schlotheimi," now Geesops schlotheimi. Other early descriptions include Gerastos cuvieri (Steininger 1831), Asteropyge punctata (Steininger 1831) and Ceratarges armatus (Goldfuss 1839). World famous pioneer trilobitologists Rudolf & Emma Richter contributed greatly to the knowledge of the trilobites from the Gees site and to trilobites in general, via an impressive number of publications. The site has been extremely popular to collectors, some of whom brought heavy equipment to dig there. In 1984 the situation became critical; the site looked like a cratered war zone. Authorities were forced to prohibit further collecting there. Today, the Gees site is protected. Germany
|Gees locality during the Devonian
||Gees locality today
Among the most common trilobites from
the Gees site are Geesops schlotheimi
(by far the most common species of Gees, with ~90% of trilobite
specimens collected there being G. schlotheimi), as well as
Gerastos cuvieri, and Cyphaspis ceratophthalma. Very rare,
but distinctive Gees taxa include Ceratarges armatus, Harpes
macrocephalus, Radiaspis radiata, and Astycoryphe
The preservation of exoskeleton at Gees is often very good, with
dark exoskeleton contrasting against lighter matrix, as in the examples
below. The best preserved sometimes show a wood-like "grain" that is a
signature of trilobites from the area.
(Richter & Richter 1956)
The site is extremely diverse in trilobites, and as is often the case in Devonian sites, the constituent orders are Phacopida, Corynexochida (Styginidae), Proetida,Lichida, Odontopleurida, and Harpetida. Here is a complete list of Gees trilobite species:
TRILOBITA OF THE GEES TRILOBITENFELDER
Gerastos cuvieri (Steininger, 1831)
|Many thanks to Benedikt Magrean and Harald
Prescher, who provided references,
images, and information in the development of this page. It certainly
not have been developed without their great help!
-o-Also thanks to Andreas Rückert, who provided excellent images of additional Gees trilobites, including Kettneraspis and Scutellum, to round out the display!
Some Gees references:
Harald Prescher's excellent website on Devonian trilobites of the Eifel Region
Basse, M., 2003. Eifel-Trilobiten 2. Phacopida 1. Goldschneck-Verlag, Korb.
Kowalski, H., 1990. Trilobiten aus dem Devon der Eifel. Aufschluss, 33:11-63.
Richter, R., 1909. Beiträge zur Kenntnis
devonischer Trilobiten aus dem Rheinischen Schiefergebirge.
Struve, W., 1970. Beiträge zur Kenntnis der Phacopina (Trilobita), 7: Phacops-Arten aus dem Rheinischen Devon. I. Senckenbergiana lethaea, 51(2/3):133-189.