''Asaphus kowalewskii'' () is one of the 35 species of

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 ...

s of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Asaphus'' (this particular species is sometimes placed in its own genus, ''Neoasaphus'').

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of this species are popular among collectors because of their prominent stalked eyes (termed "peduncles"), many an inch or more in length. In the

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

period, an inland sea formed in what is now Eastern Europe. The sea contained a remarkably diverse trilobite fauna. Over a dozen species of ''Asaphus'' developed in this sea, with many species, including unrelated species, developing long eyestalks in various lengths. That so many species of trilobite developed eyestalks suggests that they were trying to overcome increased

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids ...

, or there was some sort of massive selective pressure leading these trilobites to bury themselves in the substrate up to their eyes. This species may have lain in wait buried in a benthic layer of loose debris or sediment with only its periscope eyestalks protruding above, looking out for danger or prey. The fossils of this species are found only in the middle Ordovician deposits of the

Volkhov River The Volkhov (russian: Во́лхов) is a river in Novgorodsky and Chudovsky Districts of Novgorod Oblast and Kirishsky and Volkhovsky Districts of Leningrad Oblast in northwestern Russia. It connects Lake Ilmen and Lake Ladoga and forms pa ...

region near

Saint Petersburg Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

References

* N. Lawrow (1856). ''Verhandlungen der Kaiserlichen mineralogischen Gesellschaft zu St. Petersburg Jahr 1855–1856''. * Some of the information in this article was taken from the websit
A Guide to the Orders of Trilobites
by Sam Gon III. * Ivantsov A.U., Paleontological Journal, Vol. 37, Suppl 3, 2003. {{Taxonbar, from=Q3761788 Asaphidae Ordovician arthropods Extinct animals of Russia