Lichida is an order of typically spiny

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

that lived from the

Furongian The Furongian is the fourth and final epoch and series of the Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding ...

to the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

period. These trilobites usually have 8–13

thoracic The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main ...

segments. Their exoskeletons often have a grainy texture or have wart or spine-like tubercles. Some species are extraordinarily spiny, having spiny thoracic segments that are as long or longer than the entire body, from

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino Jr., Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont ...

(head) to pygidium (tail). The sections of the pygidia are leaf-like in shape and also typically end in spines. The order is divided into two families, Lichidae, and Lichakephalidae. Some experts group the families of the closely related order Odontopleurida within Lichida, too, whereupon the family is then divided into three superfamilies, Dameselloidea, containing the family Damesellidae, Lichoidea, containing the families Lichidae and Lichakephalidae, and Odontopleuroidea, containing the family Odontopleuridae. Lichids are some of the largest trilobites, with the second and third largest trilobites ('' Uralichas hispanicus'', and '' Teratapsis grandis'') being in the order.

Taxa traditionally placed within Lichida

As mentioned earlier, the order Lichida is divided into two families.

Lichidae

*'' Acanthopyge '' *'' Akantharges'' *'' Allolichas'' *'' Amphilichas'' *'' Apatolichas'' *'' Arctinurus'' *'' Autoloxolichas'' *'' Borealarges'' *'' Ceratarges'' *'' Conolichas'' *'' Craspedarges'' *'' Dicranogmus'' *'' Dicranopeltis'' *'' Echinolichas'' *'' Eifliarges'' *'' Gaspelichas'' *'' Hemiarges'' *'' Homolichas'' *'' Hoplolichas'' *'' Hoplolichoides'' *'' Jasperia'' *'' Leiolichas'' *''

Lichas In Greek mythology, Lichas ( ; ) was Heracles' servant, who brought the The Shirt of Nessus, poisoned shirt from Deianira to Hercules because of Deianira's jealousy of Iole, which killed him. Mythology Lichas brought to his master the deadly ...

'' *'' Lobopyge'' *'' Lyralichas'' *'' Mephiarges'' *'' Metaleiolichas'' *'' Metalichas'' *'' Metopolichas'' *'' Neolichas'' *'' Nipponarges'' *'' Ohleum'' *'' Oinochoe'' *'' Otarozoum'' *'' Paraleiolichas'' *'' Perunaspis '' *'' Platylichas'' *'' Probolichas'' *'' Pseudotupolichas'' *'' Radiolichas'' *'' Richterarges'' *'' Rontrippia'' *'' Terataspis'' *'' Terranovia'' *'' Trimerolichas'' *'' Trochurus'' *'' Uralichas'' *'' Uripes''

Lichakephalidae

*'' Acidaspidella'' *'' Acidaspides'' *'' Acidaspidina'' *'' Archikainella'' *'' Belovia'' *'' Bestjubella'' *'' Brutonia'' *'' Colossaspis'' *'' Eoacidaspis'' *'' Lichakephalus'' *'' Lichokephalina'' *'' Metaacidaspis'' *'' Paraacidaspis'' *'' Usoviana''

Cladogram

Pollit et. al. (2005) described the internal relationships below family level for Lichida.

References

External links