Charnia

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Charnia
Temporal range: Late Ediacaran, 570–550  Ma
Charnia.png
A cast of the holotype of Charnia masoni. Metric scale.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum:† Petalonamae
Family:† Charniidae
Genus:† Charnia
Ford, 1958
Species:
†C. masoni
Binomial name
†Charnia masoni
Ford, 1958
Synonyms
  • GlassnerinaGerms, 1973
  • Rangea grandisGlaessner & Wade, 1966 = Glaessnerina grandis
  • Rangea sibiricaSokolov, 1972 = Glaessnerina sibirica

Charnia is an extinct 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 (thus exhibiting glide reflection, or opposite isometry). 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.

Contents

The living organism grew on the sea floor, 570 to 550 million years ago, and is believed to have fed on nutrients in the water. Despite Charnia's fern-like appearance, it is not a photosynthetic plant or alga because the nature of the fossil beds where specimens have been found implies that it originally lived in deep water, well below the photic zone where photosynthesis can occur. [2]

Diversity

Several Charnia species were described but only the type species C. masoni is considered valid. Some specimens of C. masoni were described as members of genus Rangea or a separate genus Glaessnerina:

Two other described Charnia species have been transferred to two separate genera

A number of Ediacaran form taxa are thought to represent Charnia, Charniodiscus and other Petalonamids at varying levels of decay; these include the Ivesheadiomorphs Ivesheadia , Blackbrookia , Pseudovendia , and Shepshedia . [10]

Distribution

Charnia masoni was first described from the Maplewell Group in Charnwood Forest in England and was subsequently found in Ediacara Hills in Australia, [3] [11] Siberia and the White Sea area in Russia, [12] [13] and Precambrian deposits in Newfoundland, Canada.

It lived about 570-550 million years ago. [1]

Discovery

Charnia masoni fossil, Leicester Museum & Art Gallery, Leicester Charnia masoni fossil, New Walk Museum.jpg
Charnia masoni fossil, Leicester Museum & Art Gallery, Leicester

Charnia masoni [14] was brought to the attention of scientists by Roger Mason, a schoolboy who later became a professor of metamorphic petrology. In 1957 Mason and his friends were rock-climbing in Charnwood Forest, in what is now a protected fossil site in Central England. They noticed this unusual fossil, and Mason took a rubbing of the rock. He showed the rubbing to his father, the minister of Leicester's Great Meeting Unitarian Chapel, who also taught at Leicester University nearby and knew Trevor Ford, a local geologist. Mason took Ford to the site; Ford published the discovery in the Journal of the Yorkshire Geological Society. [15] The holotype (the actual physical example from which the species was first described) now resides, along with a cast of the related taxon Charniodiscus , in Leicester Museum & Art Gallery.

It has also been revealed that Tina Negus, then a 15-year-old schoolgirl, had seen this fossil a year before the boys [16] but her geography schoolteacher discounted the possibility of Precambrian fossils. [17] Mason acknowledges, and the museum's Charnia display explains, that the fossil had been discovered a year earlier by Negus, "but no one took her seriously". [18] She was recognised at the 50th anniversary celebrations of the official discovery.

Significance

Reconstruction of Charnia masoni at Museo delle Scienze in Trento. Charnia masoni - MUSE.jpg
Reconstruction of Charnia masoni at Museo delle Scienze in Trento.

Charnia is known from specimens as small as only 1 cm (0.39 in), and as large as 66 cm (26 in) in length. [19] It is a very significant fossil because it is the first fossil which was ever described to have come from undoubted Precambrian rocks. Prior to 1958, the Precambrian was thought to be completely devoid of fossils and consequently possibly devoid of macroscopic life. Similar fossils had been found during the 1930s (in Namibia) and the 1940s (in Australia) but these forms were assumed to be of Cambrian age and were therefore considered unremarkable at the time. Originally interpreted as an alga, Charnia was reinterpreted as a sea pen (a group related to the modern soft corals) from 1966 onwards. Acceptance of Charnia as a Precambrian lifeform resulted in recognition of other major Precambrian animal groups, although the sea pen interpretation of Charnia has been recently discredited, [20] [21] and the current "state of the art" is something of a "statement of ignorance". [22]

An alternative theory has developed, since the mid-1980s, from the work of Adolf Seilacher who suggested that Charnia belongs to an extinct group of unknown grade which was confined to the Ediacaran Period. This suggests that almost all the forms that have been postulated to be members of many and various modern animal groups are actually more closely related to each other than they are to anything else. This new group was termed the Vendobionta, [23] a clade with unknown relationship to other clades, perhaps united by its construction via unipolar iterations of one cell family.

The holotype is a major attraction at the Leicester Museum & Art Gallery. A day-long seminar in 2007 devoted to Charnia termed it "Leicester's fossil celebrity". [24]

Ecology

Diorama of Ediacaran ecosystem, with abundant Charnia fronds, at the Smithsonian National Museum of Natural History Ediacaran ecosystem diorama NMNH.jpg
Diorama of Ediacaran ecosystem, with abundant Charnia fronds, at the Smithsonian National Museum of Natural History

Little is known about the ecology of Charnia. It was benthic and sessile, anchored to the sea floor. According to one currently popular hypothesis, it probably lived in deep waters, well below the wave base, thus placing it out of range of photosynthesis. Furthermore, it has no obvious feeding apparatus (mouth, gut, etc.) so its lifestyle remains enigmatic. Some have speculated that it survived either by filter feeding or directly absorbing nutrients, and this is currently the emphasis of considerable research. [25]

The growth and development of the Ediacara biota is also a subject of continued research, and this has discredited the sea pen hypothesis. In contrast to sea pens, which grow by basal insertion, Charnia grew by the apical insertion of new buds. [22]

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 of the Neoproterozoic era that spans 96 million years from the end of the Cryogenian period at 635 Mya, to the beginning of the Cambrian period at 538.8 Mya. It is the last period of the Proterozoic eon as well as the last of the so-called "Precambrian supereon", before the beginning of the subsequent Cambrian period marks the start of the Phanerozoic eon where recognizable fossil evidence of life becomes common.

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

Dickinsonia is a genus of extinct organism, most likely an animal, that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. It is one of the best known members of the Ediacaran biota. The individual Dickinsonia typically resembles a bilaterally symmetrical ribbed oval. Its affinities are presently unknown; its mode of growth has been considered consistent with a stem-group bilaterian affinity, though various other affinities have been proposed. The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal, though these results have been questioned.

<span class="mw-page-title-main">Leicester Museum & Art Gallery</span> Museum in Leicester, England

The Leicester Museum & Art Gallery is a museum on New Walk in Leicester, England, not far from the city centre. It opened in 1849 as one of the first public museums in the United Kingdom. Leicester Museum & Art Gallery contains displays of science, history and art, both international and local. The original building was designed by Joseph Hansom, designer of the hansom cab. It has been expanded several times, most recently in 2011.

<i>Charniodiscus</i> Genus of extinct Ediacaran lifeform

Charniodiscus is an Ediacaran fossil that in life was probably a stationary filter feeder that lived anchored to a sandy sea bed. The organism had a holdfast, stalk and frond. The holdfast was bulbous shaped, and the stalk was flexible. The frond was segmented and had a pointed tip. There were two growth forms: one with a short stem and a wide frond, and another with a long stalk, elevating a smaller frond about 50 centimetres (20 in) above the holdfast. While the organism superficially resembles the sea pens (cnidaria), it is probably not a crown-group animal.

<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>Thaumaptilon</i> Genus of animals (fossil)

Thaumaptilon is a fossil genus of animals from the middle Cambrian Burgess Shale which some authors have compared to members of the Ediacaran biota, generally believed to have disappeared at the start of the Cambrian, 539 million years ago. It was up to 20 cm long, and attached itself to the sea floor with a holdfast.

<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.

Roger Mason is an English geologist. He is known as the discoverer of the original type fossil for species Charnia masoni of the genus Charnia. He is now a professor at the China University of Geosciences in Wuhan, China.

<span class="mw-page-title-main">Vendiamorpha</span> Extinct class of simple animals

Vendiamorpha is a class of extinct animals within the Ediacaran phylum Proarticulata.

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>Eoandromeda</i> Species of Ediacaran animal

Eoandromeda is an Ediacaran organism consisting of eight radial spiral arms, and known from two taphonomic modes: the standard Ediacara type preservation in Australia, and as carbonaceous compressions from the Doushantuo formation of China, where it is abundant.

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

The "ivesheadiomorphs" are a group of fossilised structures known from Ediacaran localities in England and Newfoundland. They are considered to be taphomorphs, representing the poorly preserved biological remains of various contemporary taxa such as Charnia, Charniodiscus, Bradgatia, Primocandelabrum, Pectinifrons and others, that were effaced by partial decay by micro-organisms following death on the seafloor before burial by sediment.

<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.

<span class="mw-page-title-main">Avalon explosion</span> Proposed evolutionary event in the history of metazoa, producing the Ediacaran biota

The Avalon explosion, named from the Precambrian faunal trace fossils discovered on the Avalon Peninsula in Newfoundland, eastern Canada, is a proposed evolutionary radiation of prehistoric animals about 575 million years ago in the Ediacaran period, with the Avalon explosion being one of three eras grouped in this time period. This evolutionary event is believed to have occurred some 33 million years earlier than the Cambrian explosion, which had been long thought to be when complex life started on Earth.

Beothukis mistakensis is a rare fossil frond-like member of the Rangeomorpha, described from the Ediacaran of Mistaken Point, Newfoundland. It had been identified since 1992, referred in papers as a "spatulate frond" or "flat recliner", but not formally described until 2009. The original fossils from which the genus has been described are still in situ, but replicas are preserved at the Memorial University of Newfoundland and at the Oxford University Museum of Natural History. Claims of a stem have been contentious, and based largely on structures that have subsequently been determined to be erosional scours, and is so considered to be a recliner

<i>Medusinites</i> Extinct genus of cnidarians

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.

Hadrynichorde is a frondose organism from the Ediacaran period discovered in Newfoundland, Canada. It is a sessile, benthic marine organism. resembling modern sea whips.

<i>Hapsidophyllas</i> Ediacaran rangeomorph fossil Hapsidophyllas flexibilis

Hapsidophyllas is a rare Ediacaran rangeomorph fossil found at Mistaken Point, Newfoundland, Canada. It was first identified by Emily Bamforth and Guy Narbonne in 2009. Its name comes from the Greek words for “a network of leaves.” Because its characteristic flexible leaflet structure is dissimilar to other known rangeomorphs, Bamforth and Narbonne describe it as a new rangeomorph form, called hapsidophyllid. The only other known hapsidophyllid is the Ediacaran frond Frondophyllas grandis, which shares the network-like configuration of leaflets seen in Hapsidophyllas. Currently, the Hapsidophyllas flexibilis holotype resides in its type locality in the Mistaken Point Ecological Reserve, and a cast of the specimen is on display at the Royal Ontario Museum in Toronto, Canada.

References

  1. 1 2 "Leicester's fossil celebrity: Charnia and the evolution of early life" (PDF). University of Leicester. Archived from the original (PDF) on 8 March 2021. Retrieved 5 April 2016.
  2. ↑ Hoyal Cuthill, Jennifer F.; Han, Jian (2018). Álvaro, Javier (ed.). "Cambrian petalonamid Stromatoveris phylogenetically links Ediacaran biota to later animals". Palaeontology. 61 (6): 813–823. doi:10.1111/pala.12393. ISSN   0031-0239.
  3. 1 2 Glaessner, M.F.; Wade, M. (1966). "The late Precambrian fossils from Ediacara, South Australia" (PDF). Palaeontology. 9 (4): 599.
  4. ↑ Germs, G. J. B. (1973). "A reinterpretation of Rangea schneiderhoehni and the discovery of a related new fossil from the Nama Group, South West Africa". Lethaia. 6 (1): 1–10. Bibcode:1973Letha...6....1G. doi:10.1111/j.1502-3931.1973.tb00870.x.
  5. ↑ Narbonne, G.M.; Gehling, J.G. (2003). "Life after Snowball: the oldest complex Ediacaran fossils" (PDF). Geology. 31 (1): 27–30. Bibcode:2003Geo....31...27N. doi:10.1130/0091-7613(2003)031<0027:LASTOC>2.0.CO;2. Archived from the original (PDF) on 31 October 2004.
  6. ↑ Narbonne, G.M.; Laflamme, M.; Greentree, C.; Trusler, P. (2009). "Reconstructing a lost world: Ediacaran rangeomorphs from Spaniard's Bay, Newfoundland". Journal of Paleontology. 83 (4): 503–523. Bibcode:2009JPal...83..503N. doi:10.1666/08-072R1.1. S2CID   129788025.
  7. ↑ M. Laflamme; G. M. Narbonne; C. Greentree; M. M. Anderson (2007). "Morphology and taphonomy of an Ediacaran frond: Charnia from the Avalon Peninsula of Newfoundland". Geological Society, London, Special Publications. 286 (1): 237–257. Bibcode:2007GSLSP.286..237L. doi:10.1144/SP286.17. ISBN   9781862392335. S2CID   129001821.
  8. ↑ Hofmann, H. J.; O'Brien, S. J.; King, A. F. (2008). "Ediacaran Biota on Bonavista Peninsula, Newfoundland, Canada". Journal of Paleontology. 82 (1): 1–36. Bibcode:2008JPal...82....1H. doi:10.1666/06-087.1. S2CID   130150962.
  9. ↑ Brasier, M.D.; Antcliffe, J.B.; Liu, A.G. (2012). "The architecture of Ediacaran Fronds". Palaeontology. 55 (5): 503–523. Bibcode:2012Palgy..55.1105B. doi: 10.1111/j.1475-4983.2012.01164.x . S2CID   86538017.
  10. ↑ Liu, A. G.; McIlroy, D.; Antcliffe, J. B.; Brasier, M. D. (2010). "Effaced preservation in the Ediacara biota and its implications for the early macrofossil record". Palaeontology. 54 (3): 607–630. doi: 10.1111/j.1475-4983.2010.01024.x .
  11. ↑ Nedin C.; Jenkins R.J.F. (1998). "First occurrence of the Ediacaran fossil Charnia from the southern hemisphere". Alcheringa. 22 (3/4): 315–316. Bibcode:1998Alch...22..315N. doi:10.1080/03115519808619329.
  12. ↑ Grazhdankin, Dima (2004). "Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution" (PDF). Paleobiology. 30 (2): 203–221. doi:10.1666/0094-8373(2004)030<0203:PODITE>2.0.CO;2. S2CID   129376371.
  13. ↑ Grazhdankin, D. V.; Balthasar, U.; Nagovitsin, K. E.; Kochnev, B. B. (2008). "Carbonate-hosted Avalon-type fossils in arctic Siberia". Geology. 36 (10): 803–806. Bibcode:2008Geo....36..803G. doi:10.1130/G24946A.1.
  14. ↑ Ford, T.D. (1958). "Precambrian fossils from Charnwood Forest". Yorkshire Geological Society Proceedings. 31 (3): 211–217. Bibcode:1958PYGS...31..211F. doi:10.1144/pygs.31.3.211.
  15. ↑ Mason, Roger. "The discovery of Charnia masoni" (PDF). University of Leicester. Archived from the original (PDF) on 8 March 2021. Retrieved 5 April 2016.
  16. ↑ Ford, Trevor. "The discovery of Charnia". Archived from the original on 23 July 2011. Retrieved 12 March 2011.
  17. ↑ Negus, Tina. "An account of the discovery of Charnia". Archived from the original on 23 July 2011. Retrieved 12 March 2011.
  18. ↑ Mason, Roger. "The discovery of Charnia masoni" (PDF). University of Leicester. Archived from the original (PDF) on 8 March 2021. Retrieved 5 April 2016. In April 1957, I went rock-climbing in Charnwood Forest with two friends, Richard Allen and Richard Blachford ('Blach'), fellow students at Wyggeston Grammar School, Leicester. I was already interested in geology and knew that the rocks of the Charnian Supergroup were Precambrian although I had not heard of the Australian fossils. Richard Allen and I agree that Blach (who died in the early 1960s) drew my attention to the leaf-like fossil holotype now on display in Leicester City Museum. I took a rubbing and showed it to my father, who was Minister of the Great Meeting Unitarian Chapel in East Bond Street, taught part-time at University College (soon to be Leicester University) and thus knew Trevor Ford. We took Trevor to visit the fossil site and convinced him that it was a genuine fossil. His publication of the discovery in the Journal of the Yorkshire Geological Society established the genus Charnia and aroused worldwide interest. ... I was able to report the discovery because of my father's encouragement and the enquiring approach fostered by my science teachers. Tina Negus saw the frond before I did but no one took her seriously.
  19. ↑ Dunn, Frances S.; Wilby, Philip R.; Kenchington, Charlotte G.; Grazhdankin, Dmitriy V.; Donoghue, Philip C. J.; Liu, Alexander G. (2019). "Anatomy of the Ediacaran rangeomorph Charnia masoni". Papers in Palaeontology. 5 (1): 157–176. Bibcode:2019PPal....5..157D. doi:10.1002/spp2.1234. PMC   6472560 . PMID   31007942.
  20. ↑ Antcliffe, J.B.; Brasier, M.D. (2007). "Charnia and sea pens are poles apart". Journal of the Geological Society. 164 (1): 49. Bibcode:2007JGSoc.164...49A. doi:10.1144/0016-76492006-080. S2CID   130602154.
  21. ↑ Gary C. Williams. "Aspects of the Evolutionary Biology of Pennatulacean Octocorals".
  22. 1 2 Antcliffe, J.B.; Brasier, M.D. (2008). "Charnia at 50: Developmental Models for Ediacaran Fronds". Palaeontology. 51 (1): 11–26. Bibcode:2008Palgy..51...11A. doi: 10.1111/j.1475-4983.2007.00738.x . S2CID   83486435.
  23. ↑ Seilacher, A. 1984. Late Precambrian and Early Cambrian Metazoa: preservational or real extinctions? 159–168. In Holland, H. D., Trendal, A. F. and Bernhard, S. (eds). Patterns of Change in Earth Evolution. Springer Verlag, New York, NY, 450 pp.
  24. ↑ "Leicester's fossil celebrity: Charnia and the evolution of early life" (PDF). University of Leicester. Archived from the original (PDF) on 8 March 2021. Retrieved 5 April 2016.
  25. ↑ Narbonne

An article on the discovery of Charnia masoni:

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