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''Bulbaspis'' ("bulb shield") is a late
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Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of asaphid trilobite
Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...
s of the family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
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 Trilobite#Ceph ...
found primarily in upper Ordovician-aged deepwater marine strata of Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a landlocked country primarily in Central Asia, with a European Kazakhstan, small portion in Eastern Europe. It borders Russia to the Kazakhstan–Russia border, north and west, China to th ...
, China
China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...
, and possibly Tasmania
Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...
. 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 ...
'' and ''Raphiophorus
''Raphiophorus'' is a genus of the family Raphiophoridae in the Ordovician and Silurian
The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the ...
'', 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 mechanism of evolution in which members of one 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 the opposite sex ...
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>
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, 1958See also
*List of trilobites
This list of trilobites is a comprehensive listing of all Genus, genera that have ever been included in the Arthropod class trilobite, Trilobita, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera th ...
References
Raphiophoridae Asaphida genera Ordovician trilobites of Asia Late Ordovician first appearances Late Ordovician extinctions {{Asaphida-stub