Here is one of the more sought-after trilobites of the Order Lichida,
Family Odontopleuridae known as Dicranurus monstrosus. Notice that
the librigenae are tightly attached, a sign of a well-articulated
specimen. It is found in the Devonian Aatchana deposits near Alnif,
Morocco. It is quite prone, and dominates its bed of matrix. To
me, the most impressive features are the dramatically retorted occipital
spines, looking like ram's horns. The major spines have been prepared
freestanding on the cephalon as well as those on pleural lobes,
and also the pygidial spines making for a dramatic display.
Something not typically seen are the pleural secondary spines (see
closeup in lateral view), as well as the hypostome which served
as an anchor for the mouthparts. This one took a great deal of effort
to prepare all the pleural spines free of matrix. This specimen
is truly stunning when viewed from any aspect, and is destined to
become the cornerstone of any collection, public or private. (I
apologize for the less-than-esthetic photography while still in
the shipping container, but discretion was the better part of valor
with all the spines).
what purpose could this spiny exoskeleton have been evolved? The
answer is simple -- DEFENSE!! Fish had recently evolved jaws, and
in the never-ending arms race between predator and prey, Dicranurus'
answer was a spectacular defensive array of spines. A substantial
amount of prep time goes into a dramatic specimen such as this,
with a concomitant high-end price. Nevertheless, it is still $100s
less than some I have seen for sale for a truly world-class fossil.
This is a fine example sure to become a prized member of any collection.
See my other listing for a roughly contemporary species prepared
by Bob Carroll, Oklahoma trilobite preparator nonpareil.