Olenelloides armatus

Reconstruction of Olenelloides armatus（圖片來源：Nobu Tamura，採用 CC BY-SA 4.0 授權）

Age

Cambrian（"Stage 4"）

514 Ma

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Taxonomy

Kingdom: Animalia

Phylum: Arthropoda

Class: Trilobita

Order: Redlichiida

Family: Olenellidae

Genus: Olenelloides

Species: Olenelloides armatus

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Morphological description

Olenelloides armatus is a small trilobite, reaching a maximum body length of about 1 cm. Its exoskeleton is narrow and elongated. The cephalon is hexagonal in outline, with a spine projecting from each corner. The thorax consists of nine segments, and the pygidium is extremely reduced.

Specimen of Olenelloides armatus（圖片來源：British Geological Survey，採用 CC BY-NC-SA 3.0 授權）

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Etymology

Olenell-: refers to the genus Olenellus

-oides: Greek, meaning resembling

armatus: Latin, meaning armed

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Biological description

Fossils of Olenelloides armatus have been discovered in Ross-shire, Scotland. This species belongs to an early, basal group of trilobites, characterized by a thin and flattened exoskeleton. Its cephalon is particularly distinctive, bearing six prominent spines, which is also the origin of its species name.

Researchers interpret this trilobite as a fast-moving benthic scavenger.

（Author: Bai Leng）

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References

1. Sepkoski, Jack (2002). A compendium of fossil marine animal genera (Trilobita entry). Bulletins of American Paleontology

2. McNamara, K.J. (1978). Paedomorphosis in Scottish Olenellid Trilobites (Early Cambrian), Palaeontology

3. Paleobiology Database

57.47, -5.22

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