''Halichondrites'', sometimes mis-spelt ''Halicondrites'' is an extinct genus of sea sponge known from the

Middle Cambrian Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek (di ...

Burgess Shale. 7 specimens of ''Halichondrites'' are known from the Greater Phyllopod bed, where they comprise < 0.1% of the community.

Taxonomy and species

The genus ''Halichondrites'' was erected by John William Dawson in 1889, who described the species ''Halichondrites confusus'' from the Ordovician of

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

at Little Métis. In 1920, Charles Doolittle Walcott, considering ''H. confusus'' to be inadequately described, himself described ''Halichondrites elissa'' from the

Burgess Shale, placing it as the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

of the genus. In 1936, Howell & Landes described and provisionally placed in the genus two further species from the

Lower 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. The ...

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

, ''Halichondrites? actiniformis'' and ''Halichondrites? robustus''. Another species, "''Halichondrites graphitiferus''", was described by

George Frederick Matthew George Frederick Matthew (August 12, 1837 – April 14, 1923) was a Canadian botanist and geologist. Described as an amateur geologist, he is nevertheless recognized for his work in the then-nascent field of ichnology. His work grew from study of ...

in 1890 from the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

Saint John, New Brunswick Saint John is a seaport city of the Atlantic Ocean located on the Bay of Fundy in the province of New Brunswick, Canada. Saint John is the oldest incorporated city in Canada, established by royal charter on May 18, 1785, during the reign of Ki ...

. However, the organic nature of this species has been questioned; according to Miller (1987), who examined the holotype, the "spicules" described by Matthew are more likely a combination of scratches and cleavage on graphite.

References

External links

* Burgess Shale fossils Protomonaxonida Burgess Shale sponges Prehistoric sponge genera Cambrian genus extinctions {{paleo-sponge-stub