Trilobites

Dicranurus monstrosus - a horned trilobite (Morocco)
Dicranurus (Order Lichida, Family Odontopleuridae) has one of the most bizarre morphologies of the trilobites coming from the Lower Devonian of Morocco. Most notable are the pair of swirling spines resembling horns that are attached to the occipital ring. The trilobite is both rare and quite difficult to prepare, at least with crude tools. Both are reasons that authentic specimens are expensive and frequently found as manmade specimens. The Moroccan manmade pieces are really quite a work of art and are often mis-represented as genuine trilobites. There are many manmade specimens used in educational and private displays that have too much activity for genuine museum pieces. When the matrix (or resin in the case of manmade) inside the horns has not been removed and when the matrix is a light brown color and the exoskeleton a is brown (rather than normal black being), then suspicion should be heightened that the trilobite is manmade. Dicranurus trilobites, like other trilobites, are most often made by casting in resin or plaster both the trilobite and the underneath matrix layer, with both ultimately placed in a hollowed out, piece of real matrix limestone. This is often referred to as the typical "imitated-matrix-fake". Genuine Dicranurus trilobites are normally prepared with free-standing horns, because the extra effort is warranted by the trilobites rarity. To what purpose could this spiny exoskeleton have been evolved? The answer is simple …Self Defense! Fish had recently evolved jaws, and in the never ending evolutionary race between predator and prey, Dicranurus' answer was a spectacular defensive array of spines.