Bulbaspis

Bulbaspis Temporal range: Late Ordovician PreꞒ Ꞓ O S D C P T J K Pg N
B. mirabilis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	† Trilobita
Order:	† Asaphida
Family:	† Raphiophoridae
Genus:	† Bulbaspis Chugaeva, 1956
Type species
Ampyx bulbifer Weber, 1932
Species groups [1]
See text

Bulbaspis ("bulb shield") is a late Ordovician genus of asaphid trilobites of the family Raphiophoridae found primarily in upper Ordovician-aged deepwater marine strata of Kazakhstan, China, and possibly Tasmania. Species of Bulbaspis are similar to other raphiophorids such as Ampyx 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. ^[1] The function of the bulb is currently unknown: one hypothesis suggests sexual selection may have had a role in its evolution in the genus. ^[2]

Individuals of B. brevis, demonstrating development of the bulb

Species

• ovulum group
  • B. lageniformisZhou et al. 1982
  • B. ovulumWeber 1948
  • B. ordosensisLu et al. 1976
• bulbifer group
  • B. brevisZhou & Zhou, 2006
  • B. bulbifer(Weber, 1932)
  • B. korlaensisZhang, 1981
  • B. mirabilisChugaeva, 1958
  • B. sphaerornatusChugaeva, 1958

See also

• List of trilobites

References

1. 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. "Archived copy" (PDF). Archived from the original (PDF) on 2016-05-13. Retrieved 2016-01-12.
2. Knell, Robert J., and Richard A. Fortey. "Trilobite spines and beetle horns: sexual selection in the Palaeozoic?." Biology letters 1.2 (2005): 196-199.