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Trilobites are so named for the three longitudinal lobes: 4 – right pleural lobe; 5 – axial lobe; 6 – left pleural lobe; the antennae and legs are not shown in these diagrams. Only the upper (dorsal) part of their exoskeleton is mineralized, composed of calcite and calcium phosphate minerals in a lattice of chitin , [ 68 ] and is curled ...
Diagram showing the location of the cephalon, thorax and pygidium of a trilobite. The pygidium (pl.: pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor.
English: The trilobite body is divided into three major sections : 1 – cephalon; 2 – thorax; 3 – pygidium. Trilobites are so named for the three longitudinal lobes: 4 – right pleural lobe; 5 – axial lobe; 6 – left pleural lobe; the antennae and legs are not shown in these diagrams.
Olenoides followed the basic structure of all trilobites — a cephalon (head shield), a thorax with seven jointed parts, and finally a semicircular pygidium. Its antennae were long, and curved back along its sides. Its thin legs show that it was no swimmer, instead crawling along the sea floor in search of prey.
English: Diagram showing the larger details of the cephalon of a trilobite. Fixigena; Librigena; Glabella; Date:
Olenellus is an extinct genus of redlichiid trilobites, with species of average size (about 5 centimetres or 2.0 inches long). It lived during the Botomian and Toyonian stages ( Olenellus -zone), 522 to 510 million years ago , in what is currently North-America, part of the palaeocontinent Laurentia .
Diagram showing the cephalon, thorax and pygidium of an example trilobite.. Cephalon: Opisthoparian facial sutures.Early forms tend to have tapering, conical glabella with furrows extending far backwards while later forms with glabella expanding forwards to inflated frontal lobe.
Elrathia is a genus of trilobite belonging to Ptychopariacea known from the mid-Cambrian of Laurentia (North America). [2] E. kingii is one of the most common trilobite fossils in the USA [3] locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. [4] E. kingii has been considered the most ...