.77" Pyritized Triarthrus Trilobite With Eggs & Ovarian Network!

Pyritized Triarthrus Trilobite With Eggs & Ovarian Network! #293173

This is an incredible, pyritized specimen of the trilobite Triarthrus eatoni preserving appendages, antennae, and even EGGS! Until recently little had been known about the reproduction of these iconic Paleozoic arthropods, and never before have unambiguous eggs or genitalia been found preserved. Trilobites from a single layer of the a quarry in the Whetstone Gulf Formation of New York, were found to have associated eggs still in place. The eggs are spherical to elliptical in shape, about 200 µm in size, and are clustered in the genal area of the cephalon. The location of the eggs is consistent with where modern female horseshoe crabs release their unfertilized eggs.

Below is a link to the paper published years ago on this amazing find.

Pyritized in situ trilobite eggs from the Ordovician of New York (Lorraine Group): Implications for trilobite reproductive biology

A great article on this discovery can be found below.

Wow! Fossilized trilobite eggs!

The localities that preserve trilobites with soft-bodied preservation can probably be counted on one hand. One of these localities is where this specimen is from, the historic Beecher's trilobite beds in the Lorraine Group of New York. Less than a decade ago a new locality was discovered a short distance away that has produced amazing, soft-bodied preservation of trilobites and other organisms. Because of the rapid burial of the trilobites, in an anoxic environment, the soft body parts were replaced by pyrite, preserving details not typically seen.

This Triarthrus specimen measures .77" long (including antennae) and is preserved dorsally. Eggs can be seen on one side of its head, and on the other is what's presumed to be an ovarian network that produces the eggs. A really cool specimen!

Included with this specimen are printed copies of the two cropped in photos seen above.

About Trilobites

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: over 25,000 species have been described, filling nearly every evolutionary niche. Due in large part to their hard exoskeletons (shells), they left an excellent fossil record.

More About Trilobites