Exigua

Exigua
Temporal range: Dresbachian
↓
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Ptychopariida
Superfamily: Raymondinacea
Family: Raymondinidae
Subfamily: Raymondininae
Genus: Exigua
Howell, 1937
species
  • E. quadrata Howell, 1937 (type species)
  • E. pulchellus Lochman, 1940 = Brassicicephalus pulchellus
  • E. quebeckensis (Rassetti, 1946) = Brassicicephalus quebeckensis[1]
  • E. woolfensis (Lochman, 1944) = Brassicicephalus woolfensis[2]
Synonyms

Brassicicephalus

Exigua (synonym: Brassicicephalus) is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from 501 to 497 million years ago during the Dresbachian faunal stage of the late Cambrian Period.[3] Exigua is only known from the central part of the headshield or cranidium, so free cheeks (or librigenae), thorax and pygidium are unknown.

Etymology

Exigua, is Latin meaning small, meager or sparse, referring to the small size of the only parts known of these trilobites, namely the cranidia. The synonym Brassicicephalus is a combination of Brassica (Latin, "cabbage") and cephalus (Greek: Κέφαλος Kephalos, "head") for the strongly convex glabella and fixed cheeks separated by a deep furrow.

References

  1. ↑ Robison, R.A. (1988). Peel, J.S., ed. Trilobites of the Holm Dal Formation (late Middle Cambrian), central North Greenland. Mededelser om Grønland - Geoscience. 20. pp. 94–96. ISBN 8763511908.
  2. ↑ Lochman, C.; Duncan, D. (1944). "Early Upper Cambrian Faunas of Central Montana". Geological Society of America Special Papers. 54: 13. ISBN 0813720540. doi:10.1130/spe54-p1.
  3. ↑ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology. 364: 560. Archived from the original on 2006-09-05. Retrieved 2008-01-12.


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