''Receptaculites'' is the name-bearing genus for an extinct group of conspicuous benthic marine genera, the receptaculitids (formally Receptaculitaceae or Receptaculitidae), that lived from the Early

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 ...

through the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

period, peaking in the Middle Ordovician. The group's phylogenetic origin has long been obscure, with some arguing that they were calcareous algae, probably of the order

Dasycladales Dasycladales is an Order (biology), order of large unicellular green algae in the class Ulvophyceae. It contains two families, the Dasycladaceae and the Polyphysaceae. These single celled algae are from 2 mm to 200 mm long. They liv ...

.Byrnes, J.G. 1968. Notes on the nature and environmental significance of the Receptaculitaceae. Lethaia, vol. 1, p. 368-381. Receptaculitids lived in warm, shallow seas, but consensus disagreeing. They have been described from all continents except Antarctica. In some areas they were important reef-formers, and they also occur as isolated specimens. KimmswickOzoraMidOrdReceptaculitid

''Receptaculites'' and its relatives have a double-spiral, radiating pattern of

rhombus In plane Euclidean geometry, a rhombus (: rhombi or rhombuses) is a quadrilateral whose four sides all have the same length. Another name is equilateral quadrilateral, since equilateral means that all of its sides are equal in length. The rhom ...

-shaped plates supported by spindle-like objects called meroms. Fossils can usually be identified by the intersecting patterns of clockwise and counterclockwise rows of plates or stalk spaces, superficially similar to the arrangement of disk

floret This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...

s on a

sunflower The common sunflower (''Helianthus annuus'') is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the pr ...

—hence the common name "sunflower coral" (''sic''). Receptaculitids have sometimes been compared to the morphologically similar, but probably distantly related,

cyclocrinitids Cyclocrinitids are an early (mid-Ordovician–early-Silurian) Dasycladalean algae, resembling but probably not closely related to the Receptaculitid ''Receptaculites'' is the name-bearing genus for an extinct group of conspicuous benthic ...

. Some

dolomitic Dolomite () is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite (see Dolomite (rock)). An alternative name sometimes ...

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

deposits, such as

Tyndall stone Tyndall Stone is a registered trademark name by Gillis Quarries Ltd. Tyndall Stone is a dolomitic limestone that is quarried from the Selkirk Member of the Ordovician Red River Formation in the vicinity of Garson and Tyndall, Manitoba, ...

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, Canada, are particularly rich in ''Receptaculites'' fossils.

References

{{Taxonbar, from=Q7302354 Paleozoic plants Ulvophyceae genera Fossil algae Early Ordovician first appearances Permian genus extinctions Paleozoic life of Ontario Paleozoic life of Alberta Paleozoic life of British Columbia Paleozoic life of Manitoba Paleozoic life of Newfoundland and Labrador Paleozoic life of the Northwest Territories Paleozoic life of Nunavut Paleozoic life of Quebec