Large Trilobite Plaque

Large Trilobite Plaque
Xenasaphus devexus
Middle Ordovician, Uhaku Regional Stage
Volchov River, St. Petersburg, Russia
Mass mortality plates are highly unusual in the trilobite world. Plates featuring trilobites averaging eight centimeters in length are even more rare. The present Xenasaphus devexus assemblage, found in the Ordovician strata on the outskirts of St. Petersburg, Russia, is one of the finest ever found. Trilobites were the first creatures on Earth to possess complex eyes. One of the earliest-known groups of arthropods, trilobites were among the most successful of all early animals, existing in the oceans for over 300 million years. They vanished with the Permian Extinction, 250 million years ago, long before the appearance of the first dinosaurs. Measuring 33 1/2 x 30in