Trilobite Anatomy

A relationship with the chelicerata in a clade termed arachnomorpha arachnata was in vogue for some time58 but a more recent analysis of panarthropoda suggests the trilobites are one of two major branches of artiopoda30. In insects head is a preferred term.

Pygidium Wikipedia

Only about twenty different species of trilobites have been found with preservation of antennae and limbs.

Trilobite anatomy. They patrolled hunted and scoured the oceans for over 270 million years. Both lived in silurian great britain. Trilobites evolved profound adaptations that place them among the most successful of all early animals.

Sometimes the gut or its contents are also preserved as an axial structure. Once soft part anatomy had been recovered the trilobites were originally allied to the crustacea. They can be smooth as in order asaphida or spiny as in order lichida.

To the right is an example of the olenid trilobite triarthrus eatoni showing preserved antennae legs and gill filaments. This category contains anatomical features of trilobites. X ray images of some trilobite specimens indicate a long central axial structure typically considered an alimentary canal intestines or gut.

Trilobite means three lobes this refers to their body plan. In trilobites the pygidium can range from extremely small much smaller than the head or cephalon to larger than the cephalon. Taken together a listing of such morphological features provides nothing less than a plethora of tongue twisting trilo terms.

Similarly our knowledge of the internal anatomy of trilobites is very poorly understood. Both lived in silurian great britain. Some of the genera of trilobites appearing in the ordovician include.

Trilobites occupied different levels of the food web including predator scavenger and prey. Such characteristics as occipital lobes anterior margins and facial sutures which allowed early trilobites to shed their molting shell were shared by the majority of trilobite species as were such exotic sounding features as axial rings articulating facets and pleural spines. The trilobite in the same picture is calymene blumenbachii.

Selenopeltis early to late ordovician. Cyclopyge early to late ordovician.

Trilobites Fossil Focus Time Discovering Geology