triangularis Unusual Russian Lower Ordovician Trilobite
triangularis Russian trilobites
inches (25.4mm=1 inch): 95 mm long by 50 mm wide on a 165 by 125 mm matrix.
Wolchovian Horizon of the Wolchow
River region near Saint Petersburg, Russia
A well-inflated example of an ancient member of the Asaphidae, this is Megistaspis
triangularis. It is easy to see the derivation of the species name from the triangular,
fusiform shape of this particular example of the genus. One of some 20 members
of the genus, notice the distinguishing pygidial spine, reminiscent of the younger
genus Huntonia from the Devonian of Oklahoma. It is thought that the low profile
allowed the trilobite to conceal itself just below the surface of the seafloor.