Kleptothule rasmusseni was a small, elongated trilobite

Trilobite

Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...

, about 3 cm in length, and about 5 to 6 mm in width, from the Sirius Passet

Sirius Passet

Sirius Passet is a Cambrian Lagerstätte in Greenland. The Sirius Passet Lagerstätte was named after the Sirius sledge patrol that operates in North Greenland. It comprises six localities located on the eastern shore of J.P. Koch Fjord in the far north of Greenland. It was discovered in 1984 by A....

 Lagerstätte

Lagerstätte

A Lagerstätte is a sedimentary deposit that exhibits extraordinary fossil richness or completeness.Palaeontologists distinguish two kinds....

. It is currently placed in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Nevadiidae, though this may change with further study.

Its cephalon is composed of at least five segments, and its elongated thorax

Thorax

The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

 is composed of 27+ segments. The 20 or so segments of the pygidium

Pygidium

The pygidium is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. It contains the anus and, in females, the ovipositor...

are poorly defined, as they are fused together.

External links

• Peripatus Homepage "Trilobite Origins" http://www.peripatus.gen.nz/Taxa/Arthropoda/Trilobita/TriOri.html
• http://www.palaeos.com/Paleozoic/Cambrian/Sirius_Passet.html