Parapagetia

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Parapagetia
Temporal range: Botomian
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Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Agnostida
Family: Hebediscidae
Genus:Parapagetia
Repina, 1964
Species
  • P. limbataRepina, 1964 (type)
  • P. icatunicaRepina, 1964
  • P. palaeformisRomanenko & Romanenko, 1967
  • P. planaE. Romanenko, 1978

Parapagetia is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period.

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

Fossil Preserved remains or traces of organisms from a past geological age

A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. The totality of fossils is known as the fossil record.

Arthropod phylum of animals

An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.

Contents

Distribution

Description

Like all Agnostida, the Hebediscidae are diminutive and the headshield (or cephalon) and tailshield (or pygidium) are of approximately the same size (or isopygous) and outline. In Parapagetia the glabella has parallel sides and is relatively short, slightly over half as long as the cephalon. The rear of the glabella does not carry a spine or it is short. The distance between the front of the glabella and the poorly defined anterior border is long. The axis of the pygidium consists of five rings including the terminus. The border and border furrow are together wide, but poorly defined. [1]

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. It is composed of fused body segments, sometimes with a tail, and separated from thoracic segments by an articulation.

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References

  1. 1 2 Whittington, H. B. (1997). Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. Treatise on Invertebrate Paleontology. Part O, Revised. pp. 388, 390.