| Eoporpita | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Order: | Anthoathecata |
| Family: | Porpitidae (?) |
| Genus: | † Eoporpita Wade, 1972 |
| Species: | †E. medusa |
| Binomial name | |
| †Eoporpita medusa Wade, 1972 | |
Eoporpita is a disc or ellipse-shaped Ediacaran fossil with unsure taxonomy/classification. It is known from its type species, Eoporpitamedusa, the only species within the genus Eoporpita. [1]
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 member and within the phylum Cnidaria. [1] However, more recently, Eoporpita has been reinterpreted as either a benthic organism like a xenophyophore [2] [3] or the internal contents of Aspidella , together forming a holdfast for a frond-like organism. [4] [3] More research on Eoporpita is needed.
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. [4] [2] [1] Its average radius is from 2 to over 8 cm. [1]
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' presence suggests that Eoporpita was a colonial organism. The 'tentacles' appear massed and stacked, with the fossil being tallest at the central dome and thinning out closer to its edges. [2] [1]
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. [4]
Eoporpita's namesake is Porpita , a genus of hydrozoans in the family Porpitidae. 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. [1]
Specimens of Eoporpita have been found in:
Tribrachidium heraldicum is a tri-radially symmetric fossil animal that lived in the late Ediacaran (Vendian) seas. In life, it was hemispherical in form. T. heraldicum is the best known member of the extinct group Trilobozoa.
Ediacaria is a fossil genus dating to the Ediacaran Period of the Neoproterozoic Era. Unlike most Ediacaran biota, which disappeared almost entirely from the fossil record at the end of the Period, Ediacaria fossils have been found dating from the Baikalian age of the Upper Riphean to 501 million years ago, well into the Cambrian Period. Ediacaria consists of concentric rough circles, radial lines between the circles and a central dome, with a diameter from 1 to 70 cm.
Hiemalora is a fossil of the Ediacaran biota, reaching around 3 cm in diameter, which superficially resembles a sea anemone. The genus has a sack-like body with faint radiating lines originally interpreted as tentacles, but discovery of a frond-like structure seemingly attached to some Heimalora has added weight to a competing interpretation: that it represents the holdfast of a larger organism.
Aspidella is an Ediacaran disk-shaped fossil of uncertain affinity. It is known from the single species A. terranovica.
Trilobozoa is a phylum of extinct, sessile animals that were originally classified into the Cnidaria. The basic body plan of trilobozoans is often a tri-radial or radial sphere-shaped form with lobes radiating from its centre. Fossils of trilobozoans are restricted to marine strata of the Late Ediacaran period.
The Ediacaranbiota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period. These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined.
Albumares brunsae is a tri-radially symmetrical fossil animal that lived in the late Ediacaran seafloor. It is a member of the extinct group Trilobozoa.
Anfesta stankovskii is a tri-radially symmetrical fossil animal that lived in the late Ediacaran (Vendian) seafloor. It is a member of the extinct group Trilobozoa.
Rugoconites is a genus of Ediacaran biota found as fossils in the form of a circular or oval-like impression preserved in high relief, six or more centimeters in diameter. The fossils are surrounded by frills that have been interpreted as sets of tentacles. The bifurcating radial ribs, spreading from a central dome, serve to distinguish this genus from the sponge Palaeophragmodictya, and may represent the channels of the gastrovascular system. Fossils of Rugoconites have been interpreted as early sponges, although this is countered by Sepkoski et al. (2002), who interpreted the organism as a free-swimming jellyfish-like cnidarian; similar to Ovatoscutum. However, the fossil is consistently preserved as a neat circular form and its general morphology does not vary, therefore a benthic and perhaps slow-moving or sessile lifestyle is more likely. Ivantstov & Fedonkin (2002), suggest that Rugoconites may possess tri-radial symmetry and be a member of the Trilobozoa.
Vaveliksia is an extinct genus of Ediacaran Sponge-like organism with a long, tubular-shaped body and a attachment disk similar to that of Petalonamids. The Vaveliksia genus contained two species, Vaveliksia velikanovi as well as Vaveliksia vana. The two species vary in appearance to one another, with V. velikanovi having a more tubular-shaped, sack-like morphology with a crown of wrinkles on top of one of its ends as well as possessing a much more disk-like holdfast with V. vana having an appearance more similar to that of a Poriferan, with V. vana having a much more dome-shaped holdfast and a capsule-like body with no crown of wrinkles unlike V. velikanovi.
Arumberia is an enigmatic fossil from the Ediacaran period originally described from the Arumbera Sandstone, Northern Territory, Australia but also found in the Urals, East Siberia, England and Wales, Northern France, the Avalon Peninsula and India. Several morphologically distinct species are recognized.
Veprina is a rare Ediacaran coelenterate cnidarian found on the Zimny coast of the White Sea, Russia and was first described by Mikhail Fedonkin in 1980.
Medusinites is a genus of disc shaped fossilised organisms associated with the Ediacaran biota. They have been found in rocks dated to be 580 to 541 million years old.
The Ediacaran fossil Hallidaya, a close relative of Skinnera lived in Belomorian of the Late Ediacaran period prior to the Cambrian explosion and thrived in the marine strata on the ocean floor of what is now considered Australia. These fossils were disk-shaped organisms that were slightly dome shaped with tri-radial symmetry. These Ediacaran organisms thrived by living in low-energy inner shelf, in the wave- and current-agitated shoreface, and in the high-energy distributary systems.
Persimedusites chahgazensis is a Precambrian discoidal species which are believed to have existed primarily during the late Ediacaran period. It was discovered initially in the Kushk Series in the Bafq and Behabad regions of central Iran, along with similarly aged specimen of Cloudina and Corumbella. The body fossils of these disc-shaped organisms are approximately one centimeter in diameter, and were noted to have symmetrical internal lobes, as well as secondary distal branches.
Conomedusites was a creature from the Ediacaran biota. The Ediacaran period ranged from 635 to 539 million years ago. Its fossil was first discovered in 1966 by Martin F. Glaessner and Mary Wade in South Australia. Conomedusites is believed to have been part of the phylum Cnidaria due to its similar structure to jellyfish and other cnidarians, but this is not known for certain. Conomedusites is thought to have been a stationary osmotroph.
Hadrynichorde is a frondose organism from the Ediacaran period discovered in Newfoundland, Canada. It is a sessile, benthic marine organism. resembling modern sea whips.
Bonata is a monotypic, disk-shaped genus of Ediacaran organism that were originally found in the Ediacaran deposits of the White Sea area, Russia. It has been poorly studied because of the lack of fossil specimens found in the region since the 1980's. It contains a single species, Bonata septata.
Pseudorhizostomites howchini is a enigmatic member of the Ediacaran Biota which was originally been thought to have been a jellyfish of some kind. P. howchini is now though to either have been a pseudofossil, a gas escape structure or perhaps the result of a rangeomorph holdfast being pulled by currents or, if any of these possibilities are not true, some other force from the sediments which enclosed the fossil.
Staurinidia is a genus of Ediacaran soft-bodied organism from the deposits of the Ust'-Pinega formation. It is a monotypic genus and only contains the species Staurinidia crucicula. The genus was first described in 1985 by Russian palaeontologist Mikhail A. Fedonkin. S. crucicula's four-fold symmetry is present as a result of four canals radiating from the middle of a small cavity in the middle of the body. Other forms with four way symmetry, mainly Medusoid forms, from the Ediacaran comprise an essential chunk of the Ediacaran diversity of symmetry; their organisations are of typical to that of a modern-day Scyphozoan Cnidarian although much smaller compared to them.