''Bulbaspis'' ("bulb shield") is a late

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of asaphid

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

s of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Raphiophoridae Raphiophoridae is a family of small to average-sized trilobites that first occurred at the start of the Ordovician and became extinct at the end of the Middle Silurian. Anatomy All raphiophorids are blind, with headshields (or cephalons) tha ...

found primarily in upper Ordovician-aged deepwater marine strata of

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, and possibly

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. Species of ''Bulbaspis'' are similar to other raphiophorids such as ''

Ampyx In Greek mythology, Ampyx (Ancient Greek: Ἄμπυξ) or Ampycus (Ἄμπυκος ''Ampykos'' means 'woman's diadem, frontlet') was the name of the following figures: * Ampyx, also called Ampycus or AmpyceHesiod, ''Shield of Heracles'' 180 was a ...

'' and '' Raphiophorus'', save that the long spine that emanates from the glabella of the latter two genera has been modified into a knob-like or bulb-like structure in ''Bulbaspis'' that developed incrementally in the animal's growth.Zhiqiang, Zhou, and Zhou Zhiyi. "Late Ordovician trilobites from the Zhusilenghaierhan area, Ejin Banner, western Inner Mongolia, China."MEMOIR-ASSOCIATION OF AUSTRALASIAN PALAEONTOLOGISTS 32 (2006): 383. The function of the bulb is currently unknown: one hypothesis suggests

sexual selection Sexual selection is a mode of natural selection in which members of one biological sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of t ...

may have had a role in its evolution in the genus.Knell, Robert J., and Richard A. Fortey. "Trilobite spines and beetle horns: sexual selection in the Palaeozoic?." Biology letters 1.2 (2005): 196-199

/ref> Bulbaspis_brevis

Species

* ''ovulum'' group ** ''B. lageniformis'' Zhou et al. 1982 ** ''B. ovulum'' Weber 1948 ** ''B. ordosensis'' Lu et al. 1976 * ''bulbifer'' group ** ''B. brevis'' Zhou & Zhou, 2006 ** ''B. bulbifer'' (Weber, 1932) ** ''B. korlaensis'' Zhang, 1981 ** ''B. mirabilis'' Chugaeva, 1958 ** ''B. sphaerornatus'' Chugaeva, 1958

References

Raphiophoridae Asaphida genera Ordovician trilobites of Asia Late Ordovician first appearances Late Ordovician extinctions {{silurian-animal-stub

Species

See also

References