Search results
Results From The WOW.Com Content Network
Order Ptychopariida is the most problematic order for trilobite classification. In the 1959 Treatise on Invertebrate Paleontology , [ 60 ] what are now members of orders Ptychopariida, Asaphida , Proetida and Harpetida were grouped together as order Ptychopariida; subclass Librostoma was erected in 1990 [ 61 ] to encompass all of these orders ...
The trilobite Protolenus is shown in a side view. The digestive system is seen in blue, the hypostome, or mouth structure, in green (far left) and the labrum, a bulbous structure over the mouth ...
Ptychopariida is a large, heterogeneous order of trilobite containing some of the most primitive species known. The earliest species occurred in the second half of the Lower Cambrian, and the last species did not survive the Ordovician–Silurian extinction event. Asaphiscus wheeleri, a Cambrian trilobite of the Superfamily Ptychoparioidea
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.
Asaphida is a large, morphologically diverse order of trilobites found in marine strata dated from the Middle Cambrian until their extinction during the Silurian.Asaphida contains six superfamilies (Anomocaroidea, Asaphoidea, Cyclopygoidea, Dikelocephaloidea, Remopleuridoidea and Trinucleioidea), but no suborders.
Merlinia is an extinct genus from a well-known class of fossil marine arthropods, the trilobites.It lived during the early part of the Arenig stage of the Ordovician Period, [1] a faunal stage which lasted from approximately 478 to 471 million years ago. [1]
Asaphidae is a family of asaphid trilobites.Although the first genera originate in Upper Cambrian marine strata, the family becomes the most widely distributed and most species-rich trilobite family during the Ordovician. 754 species assigned to 146 genera are included in Asaphidae.
Triarthrus is an average size trilobite (up to about 5 centimetres or 2.0 inches) and its moderately convex body is about twice as long as wide (excluding spines). Like in all Olenidae, the headshield (or cephalon ) of Triarthrus has opisthoparian sutures , and the right and left free cheeks that they define are yoked.