Trilobite Tip of the Month:


March 2001:

Drotops megalomanicus, Eifelian, Middle Devonian, Region Ma'der, SE Morocco

Drotops armatus, Eifelian, Middle Devonian, Region Ma'der, SE Morocco
 

The giant "Phacops" of Morocco:

    These giant "Phacops" from Morocco are quite well known and are one of the first and most marketable fossils from Morocco. They have been called various names by collectors over the years, the most common of which is Phacops africanus. They do not belong to this species, and in fact are not even Phacops. These giant phacopids belong to the genus Drotops Struve 1990, and were described by Struve in 1990 and 1995. Two main species occur: 1. Drotops megalomanicus Struve, 1990 and 2. Drotops armatus Struve 1995 (the Moroccans call this species "Phacops épine"). Both of these species occur in the Middle Devonian (Eifelian) of the Maïder (Ma'der) Region, SW of Erfoud, in the Pre-Sahara of SE Morocco. The most common locality for these trilobites is Djebl (Jbel) Issoumour (or Mt. Issoumour) in the upper layers of the trilobite-bearing units, but it also occurs in equivalent strata throughout the basin.
    Drotops megalomanicus Struve, 1990 is the regular form and has 2 described subspecies: D. megalomanicus megalomanicus Struve, 1995 and D. megalomanicus subornatus Struve, 1995. The spiny Drotops armatus Struve, 1995 was described by Struve (1995) to have 4 different forms (forma accurata, forma perspinosa, forma armata, and forma hoplites), based mainly on the type of spines and their arrangements.
    A further species of large phacopid was described by Struve as Pedinopariops (Hypsipariops) vagabundus Struve, 1990. This species does not grow quite as large and does not have the coarse tuberculation on the axis and pygidium (as well as other differences) as seen in the Drotops species.
    Both of Struve's papers are written in German and for anyone interested in diagnosing which subspecies or form they may have (and can read German), please contact me as I am interested in obtaining a translation. For the majority of collectors who have these large phacopids, The correct names are Phacops megalomanicus (for the regular type) and Drotops armatus (for the spiny type).
    Beware as always of fakes and forgeries of these species. The Moroccans are famous for producing forgeries that can fool even the most experienced academics. Choose a reputable trilobite dealer if you plan on purchasing any Moroccan trilobites. Ask for a guarantee of authenticity as well as a money-back guarantee if the specimen is found to be forged. Most trilobite specimens have some degree of repair. Ask for the percentage of repair to the specimen. A few ways of determining fakery are: 1. Ultraviolet light sometimes shows cracks, and different glues and epoxies. 2. A hot needle or flame may melt into suspected forged areas or produce a scent when in contact with glues and epoxies. 3. Microscope examination of the trilobite exoskeleton and microstructure (pitting, tubercles, pustules, terrace lines) and comparison with published literature and photographs.

References:

Struve (1990)  Paläozoologie III (1986-1990). - [Forschungsbericht] Cour. Forsch.-Inst. Senckenberg, 127: 251-279, Abb. 1-9; Frankfurt am Main

Struve (1995)  Beiträge zur Kenntnis der Phacopina (Trilobita), 18: Die Riesen-Phacopiden aus dem Maïder, SE-marokkanische Pra-Sahära. Senckenbergiana lethaia 75 (1/2): 77-129, 43 Abb., 11 Taf., Frankfurt am Main. 1