Petalonamae

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Petalonamae
Temporal range: 635.0–516.0  Ma
Charniodiscus arboreus.jpg
Charniodiscus arboreus (=Arborea arborea)
Scientific classification
Kingdom:
Superphylum:
Phylum:
Petalonamae

Phlug, 1972 [1]
Subtaxa [2] [3]
Synonyms
  • Frondomorpha

The petalonamids (Petalonamae) are an extinct group of archaic animals typical of the Ediacaran biota, also called frondomorphs, dating from approximately 635 million years ago to 516 million years ago. They are benthic and motionless animals, [4] that have the shape of leaves, fronds (frondomorphic), feathers or spindles and were initially considered algae, octocorals or sea pens. It is now believed that there are no living descendants of the group, which shares a probable relation to the Ediacaran animals known as Vendozoans.

Contents

It is commonly conjectured that the organisms were fluffy at least in appearance, as if "inflatable." They are particularly difficult to classify phylogenetically. Lacking mouths, intestines, reproductive organs, and with no preserved evidence of internal structures, these organisms' existence is very strange by current standards. The most widely accepted hypothesis is that they could suck nutrients from the water around them by osmosis. [5] The fronds were composed of branched, tubular structures, and the organism was anchored to the ground by a bulbous structure.

The symmetry is generally bilateral, like a feather with one axis and two sides. It can also be trilateral, with one axis and three sides, as seen in the most basal ones, the erniettomorphs. [6] [7]

Distribution

Ediacaran of Canada, Namibia and Russia. [2]

Phylogeny

Animalia
Porifera  

 ···


Petalonamae

Rangea

Stromatoveris

Pteridinium

Ernietta

Arborea

Pambikalbae

Swartpuntia

Eumetazoa

 ···

See also

Related Research Articles

<span class="mw-page-title-main">Ediacaran</span> Third and last period of the Neoproterozoic Era

The Ediacaran Period is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia.

The cloudinids, an early metazoan family containing the genera Acuticocloudina, Cloudina and Conotubus, lived in the late Ediacaran period about 550 million years ago. and became extinct at the base of the Cambrian. They formed millimetre-scale conical fossils consisting of calcareous cones nested within one another; the appearance of the organism itself remains unknown. The name Cloudina honors the 20th-century geologist and paleontologist Preston Cloud.

<i>Dickinsonia</i> Extinct genus of early animals

Dickinsonia is an extinct genus of lifeforms that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine, most likely a basal animal. The individual Dickinsonia typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth is consistent with a stem-group bilaterian affinity, though some have suggested that it belongs to the fungi, or even an "extinct kingdom". The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal.

<i>Cyclomedusa</i> Extinct genus of aquatic animals

Cyclomedusa is a circular fossil of the Ediacaran biota; it has a circular bump in the middle and as many as five circular growth ridges around it. Many specimens are small, but specimens in excess of 20 cm are known. The concentric disks are not necessarily circular, especially when adjacent individuals interfere with each other's growth. Many radial segment lines — somewhat pineapple-like — extend across the outer disks. A few specimens show what might be a stem extending from the center in some direction or other.

<i>Ausia fenestrata</i> Genus of marine filter feeders

Ausia fenestrata is a curious Ediacaran period fossil represented by only one specimen 5 cm long from the Nama Group, a Vendian to Cambrian group of stratigraphic sequences deposited in the Nama foreland basin in central and southern Namibia. It has similarity to Burykhia from Ediacaran (Vendian) siliciclastic sediments exposed on the Syuzma River of Arkhangelsk Oblast, northwest Russia. This fossil is of the form of an elongate bag-like sandstone cast tapering to a cone on one end. The surface of the fossil is covered with oval depressions ("windows") regularly spaced over the surface in the manner of concentric/parallel rows. The taxonomic identity of Ausia is unresolved.

<i>Charnia</i> Genus of frond-like lifeforms

Charnia is a genus of frond-like lifeforms belonging to the Ediacaran biota with segmented, leaf-like ridges branching alternately to the right and left from a zig-zag medial suture. The genus Charnia was named for Charnwood Forest in Leicestershire, England, where the first fossilised specimen was found. Charnia is significant because it was the first Precambrian fossil to be recognized as such.

<span class="mw-page-title-main">Rangeomorph</span> Form taxon of frondose Ediacaran fossils

The rangeomorphs are a form taxon of frondose Ediacaran fossils that are united by a similarity to Rangea. Some researchers, such as Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-looking fossils. Rangeomorphs appear to have had an effective reproductive strategy, based on analysis of the distribution pattern of Fractofusus misrai, which consisted of sending out a waterborne asexual propagule to a distant area, and then spreading rapidly from there, just as plants today spread by stolons or runners.

<span class="mw-page-title-main">Vendobionta</span> Group of extinct creatures that were part of the Ediacaran biota

Vendobionts or Vendozoans (Vendobionta) are a proposed very high-level, extinct clade of benthic organisms that made up of the majority of the organisms that were part of the Ediacaran biota. It is a hypothetical group and at the same time, it would be the oldest of the animals that populated the Earth about 580 million years ago, in the Ediacaran period. They became extinct shortly after the so-called Cambrian explosion, with the introduction of fauna formed by more recognizable groups and more related to modern animals. It is very likely that the whole Ediacaran biota is not a monophyletic clade and not every genus placed in its subtaxa is an animal.

<i>Yorgia</i> Extinct proarticulate of Russia

Yorgia waggoneri is a discoid Ediacaran organism. It has a low, segmented body consisting of a short wide "head", no appendages, and a long body region, reaching a maximum length of 25 cm (9.8 in). It is classified within the extinct animal phylum Proarticulata.

<i>Ediacaria</i> Genus of cnidarians

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.

<span class="mw-page-title-main">Rangea</span> Fossil taxon

Rangea is a frond-like Ediacaran fossil with six-fold radial symmetry. It is the type genus of the rangeomorphs.

<i>Swartpuntia</i> Extinct genus of Ediacaran fossil

Swartpuntia is a monospecific genus of erniettomorph from the terminal Ediacaran period, with at least three quilted, leaf-shaped petaloids — probably five or six. The petaloids comprise vertical sheets of tubes filled with sand. Swartpuntia specimens range in length from 12 to 19 cm, and in width from 11.5 to 140 cm. The margin is serrated, with a 1 mm wide groove. A 14 mm wide stem extends down the middle, tapering towards the top, and stopping 25 mm from the tip. The stem has a V shaped ornamentation on it. The original fossils were found at, and named after, the Swartpunt farm between Aus and Rosh Pinah in Namibia. The generic name comes from Swartpunt, meaning black point in reference to the colour of the rocks. The specific name germsi honours Gerard Germs, who studied the Nama formation of geological beds.

<span class="mw-page-title-main">Ediacaran biota</span> All organisms of the Ediacaran Period (c. 635–538.8 million years ago)

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.

<i>Ernietta</i> Extinct genus of invertebrates

Ernietta is an extinct genus of Ediacaran organisms with an infaunal lifestyle. Fossil preservations and modeling indicate this organism was sessile and “sack”-shaped. It survived partly buried in substrate, with an upturned bell-shaped frill exposed above the sediment-water interface. Ernietta have been recovered from present-day Namibia, and are a part of the Ediacaran biota, a late Proterozoic radiation of multicellular organisms. They are among the earliest complex multicellular organisms and are known from the late Ediacaran. Ernietta plateauensis remains the sole species of the genus.

The end-Ediacaran extinction is a mass extinction believed to have occurred near the end of the Ediacaran period, the final period of the Proterozoic eon. Evidence suggesting that such a mass extinction occurred includes a massive reduction in diversity of acritarchs, the sudden disappearance of the Ediacara biota and calcifying organisms, and the time gap before Cambrian organisms "replaced" them. Some lines of evidence suggests that there may have been two distinct pulses of the extinction event, one occurring 550 million years ago and the other 539 million years ago.

<i>Stromatoveris</i> Extinct genus of invertebrates

Stromatoveris psygmoglena is a genus of basal petalonam from the Chengjiang deposits of Yunnan that was originally aligned with the fossil Charnia from the Ediacara biota. However, such an affinity is developmentally implausible and S. psygmoglena is now thought to be either a sessile basal ctenophore, or a sessile organism closely related to ctenophores. Nevertheless, a 2018 phylogenetic analysis by Jennifer Hoyal Cuthill and Jian Han indicated that Stromatoveris was a member of Animalia and closely related to ediacaran frond-like lifeforms.

Protechiurus edmondsi is a species of fossil animal from the Ediacaran Nama group of Namibia. It was initially interpreted as an echiurid worm. It has been placed as a "vendobiont", on the hypothesis that the Edicarian fauna represent a distinct phylum. It has also been suggested that it may be an ecdysozoan.

<span class="mw-page-title-main">Nama Group</span>

The Nama Group is a 125,000 square kilometres (48,000 sq mi) megaregional Vendian to Cambrian group of stratigraphic sequences deposited in the Nama foreland basin in central and southern Namibia. The Nama Basin is a peripheral foreland basin, and the Nama Group was deposited in two early basins, the Zaris and Witputs, to the north, while the South African Vanrhynsdorp Group was deposited in the southern third. The Nama Group is made of fluvial and shallow-water marine sediments, both siliciclastic and carbonate. La Tinta Group in Argentina is considered equivalent to Nama Group.

<i>Medusinites</i>

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.

References

  1. Pflug, Hans D. (1 Jan 1970). "Zur Fauna der Nama-Schichten in Südwest-Afrika (Teil II)" [On the fauna of the Nama Beds in Southwest-Africa (Part II)]. Palaeontographica Abteilung A (in German). A135 (3–6): 198–231. Part II. Rangeidae, Bau und systematische Zugehörigkeit [Rangeidae, morphology and taxonomical position].
    see also
    Pflug, Hans D. (1 Jan 1970). "Zur Fauna der Nama-Schichten in Südwest-Afrika (Teil I)" [On the fauna of the Nama Beds in Southwest-Africa (Part II)]. Palaeontographica Abteilung A (in German). A134 (4–6): 226–262. Part I. Pteridinia, Bau und systematische Zugehörigkeit.
  2. 1 2 "phylum Petalonamae (Pflug, 1972)". Paleobiology database (paleobiodb.org) (basic taxon info). 121415.
  3. Seilacher, A. (2007). Trace Fossil Analysis. Springer.
  4. Ivantsov, A.Y.; Grazhdankin, D.V. (1997). "A new representative of Petalonamae from [the] upper Vendian of Arkhangelsk region". Paleontological Journal . 31 (1).
  5. Laflamme, Marc; Xiao, Shuhai; Kowalewski, Michał (2009). "Osmotrophy in modular Ediacara organisms". Proceedings of the National Academy of Sciences of the USA . 106 (34): 14438–14443. doi: 10.1073/pnas.0904836106 . PMC   2732876 . PMID   19706530.
  6. Hoyal Cuthill, Jennifer F.; Han, Jian (7 August 2018). "Cambrian petalonamid Stromatoveris phylogenetically links Ediacaran biota to later animals" (PDF). Palaeontology . 61 (6): 813–823. doi: 10.1111/pala.12393 . ISSN   0031-0239 via U. Essex.
  7. Buss, Leo W.; Seilacher, Adolf (1994). "The phylum Vendobionta: A sister group of the Eumetazoa?". Paleobiology. 20 (1): 1–4. doi:10.1017/S0094837300011088. ISSN   0094-8373. S2CID   89131248.

Further reading