14.5" Trilobite (Basseiarges) Mortality Plate - Jorf, Morocco

This is an exceptional trilobite mass mortality plate collected at the Jorf, Morocco "red site". The entire plate measures 14.5 x 10" and there are 20 complete Basseiarges trilobites, a couple of ventral Austerops trilobites and many partials of several different species.

Basseiarges is a fairly uncommon trilobite at the locality so a plate like this is a very rare find indeed. A real museum piece.

Trilobites are collected from a 15m thick section about 6km NW of Jorf, Morocco. Unlike many other localities these rocks do not have distinct deposition layers, but rather are massive. They likely represent a gigantic "mud mound" that formed at the base of a volcanic island due to mud slides. The rock is very silicified, almost like a chert, and can be quite colorful. The actual shell of the trilobites is translucent so that the trilobite tends to be the color of the rock below.

Because the rock contains a large amount of silica, it is extremely hard, and preparing trilobites from the site is difficult as the rock does not separate well from the shell. Within the 15m section only about 2m have been heavily collected, so occasionally this site will produce some extremely rare and one of a kind specimens collected in float from the other layers.

A view of the collecting locality NW of Jorf, Morocco
A view of the collecting locality NW of Jorf, Morocco

Collecting trilobites at the Jorf locality in 2015
Collecting trilobites at the Jorf locality in 2015

Trilobites were a very diverse group of extinct marine arthropods. They first appeared in the fossil record in the Early Cambrian (521 million years ago) and went extinct during the Permian mass extinction (250 million years ago). They were one of the most successful of the early animals on our planet with over 25k currently described species, filling nearly every evolutionary niche. Due in large part to a hard exoskeleton (shell), they left an excellent fossil record.
DETAILS
SPECIES
Basseiarges mellishae & Austerops
LOCATION
Jorf, Morocco
FORMATION
Bou Tchrafine Formation
SIZE
Rock 14.5x10", Trilobites average 1" long
SUB CATEGORY
ITEM
#86765
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