Trilo-Eye -- Witness to the Paleozoic

Trilo-Eye
Witness to the Paleozoic

NAVIGATION

Home
BOOKS
LINKS

INTRODUCTION

Trilobites are ancient arthropods that lived in the oceans of the world during the Paleozoic Era (545-253 MYA). Today, trilobites are found throughout the world, with representatives on every continent (except perhaps Antarctica). These arthropods, which resemble their relatives, the sow bugs, are now a large commodity on the world market. In fact, trilobites have become so popular that several localities, including the Burgess Shale in British Columbia and Swatara Gap in Pennsylvania have been completely shut to the public, due to excessive collecting by amateur paleontologists and commercial interests alike. Indeed, trilobites have become very popular in the last few years and the demand for specimens has almost overtaken the market for dinosaurs. With their compound eyes, hard exoskeletons, and remarkable array of spikes, spines, and horns, it is little wonder that the mystery of the trilobite has become such a novelty for the collector, and so fascinating to the world.

THE NINE ORDERS of TRILOBITES

Trilobites are divided into nine major orders, which are the following: Redlichiida, Odontipleuridae, Ptychopariida, Cornexochiida, Asaphidae, Phacopidae, Proetidae, Lichida and Agnostidae. Redlichiida, the giant bug order, is made up of such giants as Redlichia, Paradoxides, and Cambropallas. Odontipleurids are defined by their spinose appearance, displaying an impressive array of spikes, spines, and horns. Spinaspis, Leonaspis, Kettneraspis, and Dicranurus are several examples of the Odontipleuridae order. Ptychopariida is made up of a variety of trilobites, Ellipsocephalus, Triarthrus, and Modocia. Cornexochiida is classified by its classic roundly oval shape, such as Bumastus and Scutellum exhibit. Asaphidae is made up of Asaphids, fairly large trilobites with characteristic raised eyes that look very much like eyestalks. Some representatives of this order are Neoasaphus, Asaphus, and Kainops. The Phacopidae order is the classic, oval body and bug eyes. Such trilobites as Phacops, Drotops, and Psychopyge are in this order. Lichids are large and wide, with distinctive bodies. Dicranopeltis is such an example. Finally, agnostids are classified by their oval tie shape, two round bulges connected by two segments. Perinopsis and Agnostus, like almost all of their order, are small, less than half an inch in length. All the orders have different characteristics which make them unique. For more information on the orders, see Sam M. Gon III's page "The Eight Orders of Trilobites" (under links).

Big Bite

Trilobites come in a variety of sizes, from the infinitesmal to the simply huge. Smaller trilobites, mostly of the Order Agnostidae, can be as small as a few millimeters. Larger trilobites, mainly of the Redlichiida Order, can be six inches long and longer. Some of the Isotelus family can be large, too. Isotelus maximus is of an appreciative size at six inches; its cousin, Isotelus giganteus, fills a whole entire hillside. Besides size, several trilobites have an array of spikes, spines, or horns. Some like Dicranurus had two characteristics (spines and horns), while others, such as Terrataspis, even have three characteristics (spikes, spines and horns). Spines are thought to have been used for navigating the mud and sandy expanse of the sea floor, leaving its spineless cousins to burrow in search of safety and food. Horns and spikes, of course, have been attributed to being primarily defensive. Not many people know that trilobites were the first animals to see. With compound eyes, trilobites could see the world not unlike a fly would, with eyes positioned on top of their heads so that they could see in all directions without turning. Quite useful when predators could come along at any time looking for an easy meal. The eyes were primarily of two types -- schizochroal and holochroal. Schizochroal eyes were made up of from 300 to 800 round lenses, while holochroal eyes are made up of 100 to 15,000. One cannot possibly write anything whatsoever about trilobites without mentioning enrolling; enrolling is one of the most recognizable characteristics attributed to these bugs. Enrolling is the process in which the trilobite rolls up into a defensive ball to protect themselves, segments forming into a hard defensive shield that can be hard for similarly sized predators to penetrate. Parts of the segments lock to secure the enrolling position, helping the trilobite to survive. Some trilobites, such as Flexicalymene meeki, have become famous for their tendency to be found in small neat fossilized balls. Indeed, the trilobite is truly a unique creature, whose spikes, spines, horns, size, eyes, and ability to enroll have allowed it to live again in the eyes of their admirers today.

MY TRILOBITES

Here are some of my trilobites, most notably Dionide Holdeni of the Liberty Hall formation. This one's one of two beautiful specimens I've collected in Blacksburg. The other is now in the collections of PRI, the Paleontological Research Institution, located in Ithaca, New York. Please enjoy the images, and the site.

Dionide holdeni