''Paraceraurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

s that lived in the

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. ...

period (485.4 to 443.4 Ma). Its remains have been found in China,

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, and t ...

, Sweden and North America.''Paraceraurus'' in the Paleobiology Database
/ref> These trilobites have a rounded and moderately convex ''

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

''. ''

Glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...

'' is convex or flattened, with a sub-rectangular outline. Thorax shows eleven segments.Fossilstock
/ref>

Selected species

* ''

Paraceraurus exsul ''Paraceraurus exsul'' is a species of trilobite that lived in St. Petersburg Region and Tver Region (in erratic blocks) of Russia, Estonia, Finland (Åland, in erratic blocks), Sweden, North Germany (in erratic blocks), Lithuania and Belarus dur ...

'' * ''

Paraceraurus aculeatus ''Paraceraurus'' is a genus of trilobites that lived in the Ordovician period (485.4 to 443.4 Ma). Its remains have been found in China, Estonia, Sweden and North America. These trilobites have a rounded and moderately convex ''cephalon''. '' ...

'' * '' Paraceraurus ingricus'' * '' Paraceraurus gladiator'' * ''

Paraceraurus macrophthalmus ''Paraceraurus'' is a genus of trilobites that lived in the Ordovician period (485.4 to 443.4 Ma). Its remains have been found in China, Estonia, Sweden and North America. These trilobites have a rounded and moderately convex ''cephalon''. '' ...

'' * ''

Paraceraurus spinulosus ''Paraceraurus'' is a genus of trilobites that lived in the Ordovician period (485.4 to 443.4 Ma). Its remains have been found in China, Estonia, Sweden and North America. These trilobites have a rounded and moderately convex ''cephalon''. '' ...

References

* ''Trilobite: Eyewitness to Evolution'' by

Richard Fortey Richard Alan Fortey FRS FRSL (born 15 February 1946 in London) is a British palaeontologist, natural historian, writer and television presenter, who served as president of the Geological Society of London for its bicentennial year of 2007. Ear ...

* Trilobites of the families Cheiruridae and Encrinuridae from Estonia.] Geoloogia Instituudi Uurimused rud Inst Geol Acad Sci Est SSRTallinn, 3 1958: 165–205, 210–212. oological Record Volume 95* V. Klikushin, A. Evdokimov, A. Pilipyuk. Ordovician Trilobites of the St. Petersburg Region, Russia, 2009. Cheiruridae Ordovician trilobites of North America Ordovician trilobites of Asia Phacopida genera {{phacopida-stub