Eoporpita
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''Eoporpita'' is a disc or ellipse-shaped
Ediacaran The Ediacaran ( ) is a geological period of the Neoproterozoic geologic era, Era that spans 96 million years from the end of the Cryogenian Period at 635 Million years ago, Mya to the beginning of the Cambrian Period at 538.8 Mya. It is the last ...
fossil with unsure taxonomy/classification. It is known from its type species, ''Eoporpita'' ''medusa'', the only species within the genus ''Eoporpita''.


Classification debate/interpretations

There are a few different interpretations of ''Eoporpita''s taxonomy. The taxobox to the right describes ''Eoporpita'' as Mary Wade first did in 1972 as a
Hydrozoa Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline wat ...
member and within the phylum
Cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...
. However, more recently, ''Eoporpita'' has been reinterpreted as either a benthic organism like a
xenophyophore Xenophyophorea is a clade of foraminiferans. Xenophyophores are multinucleate unicellular organisms found on the ocean floor throughout the world's oceans, at depths of . They are a kind of foraminiferan that extract minerals from their surround ...
or the internal contents of ''
Aspidella :Aspidella'' is also a homonym for the mushroom genus '' Saproamanita. ''Aspidella'' is an Ediacaran disk-shaped fossil of uncertain affinity. It is known from the single species ''A. terranovica''. Morphology ''Aspidella'' consists of disk-s ...
'', together forming a
holdfast Holdfast most often refers to: *Holdfast (biology), a root-like structure that anchors aquatic sessile organisms to their substrate *Holdfast (tool), a tool used to secure a workpiece to a workbench or anvil Holdfast or hold fast may also refer t ...
for a frond-like organism. More research on ''Eoporpita'' is needed.


Morphology

General morphology: ''Eoporpita'' is circular with radial symmetry. Its surface is smooth with some radial striae and a raised central dome. Annular shaped chambers surround the central dome, similar in look to ring-shaped ripples in a water body. Its average radius is from 2 to over 8 cm. Wade interpretation: ''Eoporpita''s aboral surface is the side with its central dome. Two series of club-shaped 'tentacles' emanate from the central dome. The outer series of 'tentacles,' interpreted as dactylozooids, are all about the same length. On the other hand, the inner series of 'tentacles,' interpreted as gonozooids, are shorter but of varying lengths. These
zooids A zooid or zoöid is an animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooids can ...
' presence suggests that ''Eoporpita'' was a
colonial organism In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger pre ...
. The 'tentacles' appear massed and stacked, with the fossil being tallest at the central dome and thinning out closer to its edges. Holdfast interpretation: There are two series of club-shaped 'lobes' radiating from the central dome of ''Eoporpita''. The outer series of 'lobes' are all of relatively the same length, while the inner 'lobes' are shorter but of varying lengths. These lobes are most likely hollow and separated as opposed to massed together. The 'lobes' appear to form tiers.


Etymology

''Eoporpita''s namesake is ''
Porpita ''Porpita'' is genus of hydrozoans in the family Porpitidae. It has two species recognized and is the type genus of its family. ''Porpita'' is in the phylum Cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 spe ...
'', a genus of hydrozoans in the family
Porpitidae The chondrophores or porpitids are a small group of hydrozoans in the family Porpitidae. Though it derives from an outdated name for this lineage, some find the term ''chondrophore'' still useful as a synonym for members of the family Porpitida ...
. When describing ''Eoporpita'' in 1972, Mary Wade noticed slight similarities in their affinities. However, Wade ultimately decided that ''Eoporpita''s 'tentacles,' which she interpreted as dactylozooids and gonozooids, differentiated the two enough.


Occurrence

Specimens of ''Eoporpita'' have been found in: *
Flinders Ranges The Flinders Ranges are the largest mountain ranges in South Australia, which starts about north of Adelaide. The ranges stretch for over from Port Pirie to Lake Callabonna. The Adnyamathanha people are the Aboriginal group who have inhab ...
, Australia *
Mackenzie Mountains The Mackenzie Mountains are a Canadian mountain range forming part of the Yukon–Northwest Territories boundary between the Liard and Peel rivers. The range is named in honour of Canada's second prime minister, Alexander Mackenzie. Nahanni ...
, Northwest Territories, Canada * White Sea, Russia


See also

*
List of Ediacaran genera The existence of life, especially that of animals, before the Cambrian had long been the subject of debate in paleontology. The apparent suddenness of the Cambrian explosion had no firm explanation, and Charles Darwin himself recognized the chal ...
* ''
Aspidella :Aspidella'' is also a homonym for the mushroom genus '' Saproamanita. ''Aspidella'' is an Ediacaran disk-shaped fossil of uncertain affinity. It is known from the single species ''A. terranovica''. Morphology ''Aspidella'' consists of disk-s ...
''


References

{{Taxonbar, from1=Q3726734, from2=Q131679196 Ediacaran Canada Anthoathecata Monotypic prehistoric cnidarian genera Ediacaran life