Praecambridium sigillum ("Sigil of the Precambrian") resembles a segmented 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...

-like arthropod

Arthropod

An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...

, though many experts place it within the proarticulata

Proarticulata

Proarticulata is a proposed extinct phylum of very early bilateral animals known from fossils found in the Ediacaran fauna. Mikhail A. Fedonkin describes animals in Proarticulata as having a "shield-like" shape, an unmineralized, thin, flexible carapace and a thick, segmented body...

n 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...

 Dickinsoniidae

Dickinsoniidae

The Dickinsoniidae are an enigmatic group of Ediacaran fossils with an airbed-like quilted morphology, sometimes found in association with bizarre trace fossils....

. It is from either the Late Precambrian

Precambrian

The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

 or Lower Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 of Ediacara Hills

Ediacara Hills

Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around 650 km north of Adelaide. The area has many old copper and silver mines from mining activity in the late 19th century...

, Australia, about 590 to 530 million years ago. This beast is known from 13 specimens. On average, P. sigillum had at least 5 segments, each becoming progressively larger as they approach the cephalon.

External links

• Entry from "The Paleobiology Database http://paleodb.org/cgi-bin/bridge.pl?action=displayCollectionDetails&collection_no=10521