Petalonamae

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.

For similar fossils, see Ediacaran biota.

Petalonamae
Temporal range: Ediacaran-Cambrian
Charniodiscus arboreus (=Arborea arborea)
Scientific classification
Kingdom:
Animalia
Superphylum:
†Vendobionta
Phylum:
†Petalonamae

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

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

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. "†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


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