THE TRILOBITE

 

 

        I keep this plastic replica of a trilobite in my pocket, because it's really neat, it fits well, and doesn't bother my leg.  And also I'm probably the only person on my block with a trilobite in his pocket.

       The following is taken from The Real Book about Prehistoric Life, by Dorothy E. Shuttlesworth, so you, too, can be fascinated by these creatures.

 

 

       "The first part of the Paleozoic era is often referred to as the Age of Invertebrates.

       "There was great difference in form and size in the various invertebrates, though most of them had shells of one kind or another.  Most outstanding of them all were the trilobites.  They are not given this rating because they were the largest or most impressive in appearance; trilobites are considered so successful because for many millions of years they dominated the earth scene.  Fossil discoveries show that at least two thousand different varieties lived in widely scattered parts of the earth.  The largest kind measured two feet in length, but the majority were no more than one and a half to three inches in length.  The trilobites varied in habits as they did in size but there were some features that were alike in all.

       "The word 'trilobite,' meaning 'three-lobed fossil,' refers to the fact that the upper surface of the creature - a shell - was divided into three distinct parts by two clearly marked furrows running from front to back.  The body also was divided into three sections of head, thorax and tail, and the thorax was divided into sections which could move against one another.  Because of this, the trilobite could roll itself into a ball beneath its protecting shell.  Other reasons for the trilobites' success were their eyes and legs.  The legs, sometimes many pairs of them, ran right down the underside of the body.  Each was divided into two parts, one suitable for walking, the other for swimming.  Spines which projected from the inner sides of the legs served as jaws: the trilobite would crouch on top of its prey and 'chew' with its legs before passing the food forward to the mouth.  The trilobite's eyes were sometimes held up from the head on stalks, but even if they did not have the advantage of this elevation, they were slightly raised and could look backwards, sideways or upward.  A pair of feelers at the front of the head detected food on the sea floor.

       "It is quite certain that the trilobites ate various kinds of food.  Some may have lived entirely on a meat diet, preying upon small creatures such as worms; others doubtless found nourishment in seaweed and decaying vegetable matter.  Some spent their lives buried in the sea floor, extracting their food from the mud.  These burrowers after a while lost the use of their eyes.  A growing trilobite lived through periods of especial danger when its protective shell became too tight and had to be shed.  The shell would split at the head, allowing the soft-bodied inhabitant to creep forth.  Now at the mercy of all flesh-eaters, it would lie quietly among the seaweed until a new shell had formed.

       "Trilobites are classed as arthropods, or 'creatures with jointed feet.'  Today the arthropods are represented by such animals as lobsters, centipedes and scorpions."