Marrella

Last updated

Marrella
Temporal range: Mid Cambrian
Marrella from Burgess Shale Fossils.jpg
Fossil of Marrella
Marrella.png
Life reconstruction of Marrella
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class:† Marrellomorpha
Order:† Marrellida
Family:† Marrellidae
Genus:† Marrella
Walcott, 1912
Species:
†M. splendens
Binomial name
†Marrella splendens
Walcott, 1912

Marrella is an extinct genus of marrellomorph arthropod known from the Middle Cambrian of North America and Asia. It is the most common animal represented in the Burgess Shale of British Columbia, Canada, with tens of thousands of specimens collected. Much rarer remains are also known from deposits in China.

Contents

History

Marrella was the first fossil collected by Charles Doolittle Walcott from the Burgess Shale, in 1909. [1] Walcott described Marrella informally as a "lace crab" and described it more formally as an odd trilobite. It was later reassigned to the now defunct class Trilobitoidea in the Treatise on Invertebrate Paleontology . In 1971, Whittington undertook a thorough redescription of the animal and, on the basis of its legs, gills and head appendages, concluded that it was neither a trilobite, nor a chelicerate, nor a crustacean. [2]

Marrella is one of several unique arthropod-like organisms found in the Burgess Shale. Other examples are Opabinia and Yohoia . The unusual and varied characteristics of these creatures were startling at the time of discovery. The fossils, when described, helped to demonstrate that the soft-bodied Burgess fauna was more complex and diverse than had previously been anticipated. [3]

Morphology

Marrella splendens by Haug et al. 2012 Top left- dorsal view on a rendered 3D model top right and centre right- micrographs under polarized light top right - well preserved specimen USNM 83486f with the exopods in a "rusty" preservation (cf. Garcia-Bellido and Collins 2006) bottom left - stereo image of specimen USNM 139665. Exopods of preceding limbs are super-imposing each other, separated by a thin layer of sediment bottom right - detail of specimen ROM 56766A in "rusty" preservation. Here the spines on the lateral side of the exopod ringlets are well preserved centre right - one of the smallest specimens of M. splendens USNM 219817e that possesses preserved appendage remains Black bars for centre right image = 0.6mm, rest = 1mm Marrella splendens by Haug et al.png
Marrella splendens by Haug et al. 2012
Top left– dorsal view on a rendered 3D model
top right and centre right– micrographs under polarized light
top right – well preserved specimen USNM 83486f with the exopods in a "rusty" preservation (cf. García−Bellido and Collins 2006)
bottom left – stereo image of specimen USNM 139665. Exopods of preceding limbs are super−imposing each other, separated by a thin layer of sediment
bottom right – detail of specimen ROM 56766A in "rusty" preservation. Here the spines on the lateral side of the exopod ringlets are well preserved
centre right – one of the smallest specimens of M. splendens USNM 219817e that possesses preserved appendage remains Black bars for centre right image = 0.6mm, rest = 1mm

Specimens of Marrella range from 2.4 to 24.5 millimetres (0.094 to 0.965 in) in length. The head shield had two pairs of long posteriorly curved projections/spines, the posterior pair of which had a serrated keel. There is no evidence of eyes. On the underside of the head was a pair of long and sweeping flexible antennae, composed of about total 30 segments, projecting forward at an angle of 15 to 30 degrees away from the midline. On part of the antennae, the joints between segments bear setae. Behind and slightly above the antennae attached a pair of short and stout paddle-like swimming appendages, composed of one long basal segment and five shorter segments, the edges of the latter of which were fringed with setae. [5] [2]

The body had a minimum of 17 segments (tagma), increasing to over 26 segments in larger specimens, each with a pair of branched biramous appendages. The lower branches of each appendage (the endopod) were elongate and leg-like with 5 segments/podomeres excluding the basal segment/basipod, with the terminal segments being tipped with claws. The endopods sequentially decreased in size posteriorly, with the size reduction accelerating beyond the 9th pair. The upper branch (the exopod), which functioned as gill was segmented and bore thin filamentous structures. There is a tiny, button-like telson at the end of the thorax. [5] [2]

A 1998 paper suggested that striations present on the front projection of well-preserved specimens of Marrella represented a diffraction grating pattern, that in life would have resulted in an iridescent sheen. [6] However the conclusions of the paper regarding other animals with supposed iridescent diffraction gratings have been questioned by other authors. [7] [8] Dark stains are often present at the posterior regions of specimens, probably representing extruded waste matter [9] or hemolymph. [10] A single specimen caught in the act of ecdysis (moulting) is known, which shows that the exoskeleton split at the front of the shield. [11] [12]

Ecology

Marrella is likely to have been an active swimmer that swam close to the seafloor (nektobenthic) with its swimming appendages used in a backstroke motion, with the large spines acting as stabilizers, as well as possibly also having a defensive function. They have been suggested to be filter feeders, with food particles sifted out of the water column by the posterior appendages during swimming before being passed forward by the appendages towards the mouth. [5]

Taxonomy

Marrella is placed within the Marrellida clade of the Marrellomorpha, a group of arthropods with uncertain affinities known from the Cambrian to Devonian. Within the Marrellida, is it placed as the most basal known member of the group. Cladogram of Marrellida after Moysiuk et al. 2022 [13]

Marrellida

"Mimetaster" florestaensis Mimetaster florestaensis carapace.png

Furca bohemica Furca bohemica reconstruction.png

Mimetaster hexagonalis Mimetaster hexagonalis reconstruction.jpg

Tomlinsonus dimitrii Tomlinsonus (white background).png

Moroccan marrellid Furca mauritanica diagram.png

Marrella Marrella.png

Occurrence

Marrella is the most abundant genus in the Burgess Shale. [14] Most Marrella specimens herald from the 'Marrella bed', a thin horizon, but it is common in most other outcrops of the shale. Over 25,000 specimens have been collected. [15] 5028 specimens of Marrella are known from the Greater Phyllopod bed, where they comprise 9.56% of the community. [16]

A few dozen specimens of an indeterminate species of Marrella have been reported from the Kaili Formation of Yunnan, China, dating to the Wuliuan stage of the Cambrian. A single fragmentary specimen of an indeterminate species is also known from the Balang Formation of Yunnan, China, dating to Cambrian Stage 4. Both deposits are earlier than the Burgess Shale. [17]

See also

Related Research Articles

<i>Opabinia</i> Extinct stem-arthropod species found in Cambrian fossil deposits

Opabinia regalis is an extinct, stem group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and its segmented trunk had flaps along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.

<i>Aysheaia</i> Extinct genus of soft-bodied animals

Aysheaia is an extinct genus of soft-bodied lobopodian, known from the Middle Cambrian Burgess Shale of British Columbia, Canada

<i>Sidneyia</i> Extinct genus of arthropods

Sidneyia is an extinct arthropod known from fossils found from the Early to the Mid Cambrian of China and the Mid Cambrian Burgess Shale of British Columbia, Canada.

<i>Anomalocaris</i> Extinct genus of cambrian radiodont

Anomalocaris is an extinct genus of radiodont, an order of early-diverging stem-group arthropods.

<i>Canadaspis</i> Extinct genus of arthropods

Canadaspis is an extinct genus of bivalved Cambrian arthropod, known from North America and China. They are thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. They have been placed within the Hymenocarina, which includes other bivalved Cambrian arthropods.

<i>Odontogriphus</i> Genus of soft-bodied animals from middle Cambrian

Odontogriphus is a genus of soft-bodied animals known from middle Cambrian Lagerstätte. Reaching as much as 12.5 centimetres (4.9 in) in length, Odontogriphus is a flat, oval bilaterian which apparently had a single muscular foot and a "shell" on its back that was moderately rigid but of a material unsuited to fossilization.

<i>Waptia</i> Cambrian arthropod

Waptia is an extinct genus of arthropod from the Middle Cambrian of North America. It grew to a length of 6.65 cm (3 in), and had a large bivalved carapace and a segmented body terminating into a pair of tail flaps. It was an active swimmer and likely a predator of soft-bodied prey. It is also one of the oldest animals with direct evidence of brood care. Waptia fieldensis is the only species classified under the genus Waptia, and is known from the Burgess Shale Lagerstätte of British Columbia, Canada. Specimens of Waptia are also known from the Spence Shale of Utah, United States.

A number of assemblages bear fossil assemblages similar in character to that of the Burgess Shale. While many are also preserved in a similar fashion to the Burgess Shale, the term "Burgess Shale-type fauna" covers assemblages based on taxonomic criteria only.

<i>Canadia spinosa</i> Species of annelid (fossil)

Canadia is a genus of extinct annelid worm present in Burgess Shale type Konservat-Lagerstätte. It is found in strata dating back to the Delamaran stage of the Middle Cambrian around 505 million years ago, during the time of the Cambrian explosion. It was about 3 centimeters in length. Charles Doolittle Walcott named Canadia in 1911 after Canada, the country from which its remains have been found. 28 specimens of Canadia are known from the Greater Phyllopod bed, where they comprise 0.05% of the community.

<i>Plenocaris</i> Extinct genus of arthropods

Plenocaris plena is a Cambrian arthropod with a bivalved carapace, and is known from the Burgess shale and Chengjiang. Originally described as a species of Yohoia by Walcott in 1912, it was placed into its own genus in 1974.

<i>Isoxys</i> Genus of extinct arthropods

Isoxys is a genus of extinct bivalved Cambrian arthropod; the various species of which are thought to have been freely swimming predators. It had a pair of large spherical eyes, and two large frontal appendages used to grasp prey.

<span class="mw-page-title-main">Radiodonta</span> Extinct order of basal arthropods

Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. They may be referred to as radiodonts, radiodontans, radiodontids, anomalocarids, or anomalocaridids, although the last two originally refer to the family Anomalocarididae, which previously included all species of this order but is now restricted to only a few species. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and used for a variety of functions. Radiodonts included the earliest large predators known, but they also included sediment sifters and filter feeders. Some of the most famous species of radiodonts are the Cambrian taxa Anomalocaris canadensis, Hurdia victoria, Peytoia nathorsti, Titanokorys gainessii, Cambroraster falcatus and Amplectobelua symbrachiata, the Ordovician Aegirocassis benmoulai and the Devonian Schinderhannes bartelsi.

<i>Hurdia</i> Extinct genus of radiodonts

Hurdia is an extinct genus of hurdiid radiodont that lived 505 million years ago during the Cambrian Period. Fossils have been found in North America, China and the Czech Republic.

<span class="mw-page-title-main">Marrellomorpha</span> Extinct class of arthropods

Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. They lacked mineralised hard parts, so are only known from areas of exceptional preservation, limiting their fossil distribution. The best known member is Marrella, with thousands of specimens found in the Cambrian aged Burgess Shale of Canada. The group is divided up into two major orders, Marrellida and Acercostraca. Marrellida is recognised by the possession of head shields with two or three pairs of elongate spine-like projections, and three pairs of uniramous appendages on the cephalon, while Acercostraca generally have large ovoid carapaces that cover the entire upper half of the body, and five pairs of uniramous cephalic appendages. Both groups have unbranched antennules and a segmented trunk with biramous appendages. Recent research has suggested the previously enigmatic Cambrian trilobite-like arthropods Skania and Primicaris belong to this group. Their phylogenetic position is uncertain, various studies have alternatively placed them in the Arachnomorpha as relatives of Artiopoda, as related to Mandibulata, or as stem group euarthropods.

The fossils of the Burgess Shale, like the Burgess Shale itself, are fossils that formed around 505 million years ago in the mid-Cambrian period. They were discovered in Canada in 1886, and Charles Doolittle Walcott collected over 65,000 specimens in a series of field trips up to the alpine site from 1909 to 1924. After a period of neglect from the 1930s to the early 1960s, new excavations and re-examinations of Walcott's collection continue to reveal new species, and statistical analysis suggests that additional discoveries will continue for the foreseeable future. Stephen Jay Gould's 1989 book Wonderful Life describes the history of discovery up to the early 1980s, although his analysis of the implications for evolution has been contested.

<span class="mw-page-title-main">History of the Burgess Shale</span>

The Burgess Shale, a series of fossil beds in the Canadian Rockies, was first noticed in 1886 by Richard McConnell of the Geological Survey of Canada (GSC). His and subsequent finds, all from the Mount Stephen area, came to the attention of palaeontologist Charles Doolittle Walcott, who in 1907 found time to reconnoitre the area. He opened a quarry in 1910 and in a series of field trips brought back 65,000 specimens, which he identified as Middle Cambrian in age. Due to the quantity of fossils and the pressures of his other duties at the Smithsonian Institution, Walcott was only able to publish a series of "preliminary" papers, in which he classified the fossils within taxa that were already established. In a series of visits beginning in 1924, Harvard University professor Percy Raymond collected further fossils from Walcott's quarry and higher up on Fossil Ridge, where slightly different fossils were preserved.

<i>Molaria</i> Extinct genus of arthropods

Molaria is a genus of Cambrian arthropod, the type species M. spinifera is known from the Middle Cambrian Burgess Shale. 144 specimens of Molaria are known from the Greater Phyllopod bed, where they comprise 0.27% of the community. A second species M. steini was described from the Sirius Passet in Greenland in 2017.

<i>Mimetaster</i> Extinct genus of arthropods

Mimetaster is an extinct genus of marrellomorph arthropod. The type species, Mimetaster hexagonalis is known from the Lower Devonian (Pragian-Emsian) Hunsrück Slate, and amongst the most common arthropods from the locality, with over 120 specimens including three juveniles.

<i>Titanokorys</i> Extinct genus of giant hurdiid radiodont

Titanokorys is a genus of extinct hurdiid radiodont that existed during the mid Cambrian. It is the largest member of its family from the Cambrian, with a body length of 50 cm (20 in) long, making it one of the largest animals of the time. It bears a resemblance to the related genus Cambroraster. Fossils of T. gainesi were first found within Marble Canyon in 2018. The fossils were not named until 2021 because they were assumed to be giant specimens of Cambroraster.

<span class="mw-page-title-main">Paleobiota of the Burgess Shale</span>

This is a list of the biota of the Burgess Shale, a Cambrian lagerstätte located in Yoho National Park in Canada.

References

  1. ↑ Gould, Stephen Jay (2000). Wonderful Life: Burgess Shale and the Nature of History. Vintage. p. 108. ISBN   978-0-09-927345-5. OCLC   45316756. Also OCLC   44058853.
  2. 1 2 3 Whittington, H. B. (1971). "Redescription of Marrella splendens (Trilobitoidea) from the Burgess Shale, Middle Cambrian, British Columbia" (PDF). Bulletin – Geological Survey of Canada. Geological Survey of Canada. 209: 1–24.
  3. ↑ Gould, Stephen Jay (2000). Wonderful Life: Burgess Shale and the Nature of History. Vintage. p. 173. ISBN   978-0-09-927345-5. OCLC   45316756. Also OCLC   44058853.
  4. ↑ Haug, J. T., Castellani, C., Haug, C., Waloszek, D., Maas, A. (2012). A Marrella−like arthropod from the Cambrian of Australia: a new link between "Orsten"−type and Burgess Shale assemblages. Acta Palaeontologica Polonica 58: 629–639. doi:10.4202/app.2011.0120
  5. 1 2 3 García-Bellido, Diego & Collins, Desmond. (2006). A new study of Marrella splendens (Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada. Canadian Journal of Earth Sciences. 43. 721-742. 10.1139/e06-012.
  6. ↑ Parker, A. R. (1998). "Colour in Burgess Shale animals and the effect of light on evolution in the Cambrian". Proceedings of the Royal Society B: Biological Sciences. 265 (1400): 967–972. doi:10.1098/rspb.1998.0385. PMC   1689164 .
  7. ↑ Smith, Martin R. (January 2014). Lane, Phil (ed.). "Ontogeny, morphology and taxonomy of the soft-bodied Cambrian 'mollusc' Wiwaxia". Palaeontology. 57 (1): 215–229. Bibcode:2014Palgy..57..215S. doi: 10.1111/pala.12063 . S2CID   84616434. The full width of each sclerite [of Wiwaxia] is striated by finely spaced longitudinal lineations. Parker (1998) argued that these were superficial – although they are not visible on surfaces imaged under SEM and do not exhibit interference under transmitted light, so might be better interpreted as internal channels indicating microvillar secretion.
  8. ↑ Parry, Luke; Caron, Jean-Bernard (2019-09-06). "Canadia spinosa and the early evolution of the annelid nervous system". Science Advances. 5 (9): eaax5858. Bibcode:2019SciA....5.5858P. doi:10.1126/sciadv.aax5858. ISSN   2375-2548. PMC   6739095 . PMID   31535028. In Canadia, longitudinal striations along chaetae, which have previously interpreted as external evidence for iridescence, are concordant with the dimensions of microvilli and represent internal rather than external features.
  9. ↑ Whittington, H. B. (1978). "The Lobopod Animal Aysheaia pedunculata Walcott, Middle Cambrian, Burgess Shale, British Columbia". Phil. Trans. R. Soc. Lond. B. 284 (1000): 165–197. Bibcode:1978RSPTB.284..165W. doi: 10.1098/rstb.1978.0061 .
  10. ↑ Pratt, Brian R.; Pushie, M. Jake; Pickering, Ingrid J.; George, Graham N. Synchrotron Imaging of Burgess Shale Fossils: Evidence for Biochemical Copper (Hemocyanin) in the Middle Cambrian Arthropod Marrella splendens. Archived from the original on 2016-03-09.
  11. ↑ Drage, Harriet B.; Legg, David A.; Daley, Allison C. (2023-08-21). "Novel marrellomorph moulting behaviour preserved in the Lower Ordovician Fezouata Shale, Morocco". Frontiers in Ecology and Evolution. 11. doi: 10.3389/fevo.2023.1226924 . ISSN   2296-701X.
  12. ↑ García-Bellido, Diego C.; Collins, Desmond H. (May 2004). "Moulting arthropod caught in the act". Nature. 429 (6987): 40. Bibcode:2004Natur.429...40G. doi: 10.1038/429040a . ISSN   0028-0836. PMID   15129272.
  13. ↑ Moysiuk, Joseph; Izquierdo-López, Alejandro; Kampouris, George E.; Caron, Jean-Bernard (July 2022). "A new marrellomorph arthropod from southern Ontario: a rare case of soft-tissue preservation on a Late Ordovician open marine shelf". Journal of Paleontology. 96 (4): 859–874. Bibcode:2022JPal...96..859M. doi:10.1017/jpa.2022.11. ISSN   0022-3360.
  14. ↑ Bottjer, David J.; Etter, Walter; Hagadorn, James W.; Tang, Carol M. (2002). Exceptional Fossil Preservation: A unique view on the evolution of marine life. Columbia University Press. p. 70. ISBN   978-0-231-10255-1. OCLC   47650949.
  15. ↑ García-Bellido, D. C.; Collins, D. H. (2004). "Moulting arthropod caught in the act". Nature . 429 (6987): 40. Bibcode:2004Natur.429...40G. doi: 10.1038/429040a . PMID   15129272. S2CID   40015864.
  16. ↑ Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. Bibcode:2006Palai..21..451C. doi:10.2110/palo.2003.P05-070R. JSTOR   20173022. S2CID   53646959.
  17. ↑ Liu, Qing (May 2013). "The First Discovery of Marrella (Arthropoda, Marrellomorpha) from the Balang Formation (Cambrian Series 2) in Hunan, China". Journal of Paleontology. 87 (3): 391–394. Bibcode:2013JPal...87..391L. doi:10.1666/12-118.1. ISSN   0022-3360. S2CID   129018525.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.