Marrellomorpha

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Marrellomorpha
Temporal range:
Middle Cambrian - Early Devonian, 508–390  Ma
Marrella.png
Life restoration of Marrella from the Burgess Shale
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Marrellomorpha
Beurlen, 1930
Subgroups

Marrellomorpha are an extinct group of arthropods known from the Cambrian to the Early Devonian. [1] 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. [2] Recent research has suggested the previously enigmatic Cambrian trilobite-like arthropods Skania and Primicaris belong to this group. [3] [2] Their phylogenetic position is uncertain, various studies have alternatively placed them in the Arachnomorpha as relatives of Artiopoda (trilobites and kin), as related to Mandibulata, or as stem group euarthropods. [2] Some authors have proposed that they may be closely related to sea spiders (Pycnogonida) within Chelicerata though the cladistical support for such a relationship is relatively weak. [2]

Contents

Taxonomy

After Moysiuk et al., 2022. [2]

Fragmentary taxa assigned to Marrellomorpha include Austromarrella from Cambrian Series 3 aged deposits in Australia, [4] and Dyrnwynia from the Ordovician (Darriwilian) aged Llanfallteg Formation of Wales, which in its original description was assigned to Marrelida. [5]

Phylogeny

After Legg, 2016. [6]

Outgroups

Marrellomorpha

After Moysiuk et al., 2022. [2]

Taxa usually not
considered marrellomorphs

Related Research Articles

<i>Marrella</i> Extinct genus of Arthropods

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.

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

Skania is a Cambrian fossil arthropod. The type species, S. fragillis, is known from the Burgess Shale of British Columbia, Canada. A second possible species "S." sundbergi is known from the Kaili Formation of China, but its placement within the genus has been questioned.

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

Dinocaridida is a proposed fossil taxon of basal arthropods, which flourished during the Cambrian period and survived up to Early Devonian. Characterized by a pair of frontal appendages and series of body flaps, the name of Dinocaridids refers to the suggested role of some of these members as the largest marine predators of their time. Dinocaridids are occasionally referred to as the 'AOPK group' by some literatures, as the group composed of Radiodonta, Opabiniidae, and the "gilled lobopodians" Pambdelurion and Kerygmachelidae. It is most likely paraphyletic, with Kerygmachelidae and Pambdelurion more basal than the clade compose of Opabiniidae, Radiodonta and other arthropods.

<span class="mw-page-title-main">Cheiruridae</span> Extinct family of trilobites

Cheiruridae is a family of phacopid trilobites of the suborder Cheirurina. Its members, as with other members of the suborder, had distinctive pygidial modified into finger-like spines. They first appeared in the uppermost Cambrian, and persisted until the end of the Middle Devonian (Givetian). Currently about 657 species assigned to 99 genera are included.

<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.

<i>Primicaris</i> Extinct Genus of Cambrian Arthropod

Primicaris is genus of Cambrian arthropod from the Chengjiang biota of China and the Burgess Shale of Canada. It contains a single described species, P. larvaformis.

<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. Radiodonts are distinguished by their distinctive frontal appendages, which are morphologically diverse and were used for a variety of functions. Radiodonts were among the earliest large predators, 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 gainesi, Cambroraster falcatus and Amplectobelua symbrachiata. The later surviving members include the subfamily Aegirocassisinae from the Early Ordovician of Morocco and the Early Devonian member Schinderhannes bartelsi from Germany.

<i>Mollisonia</i> Extinct genus of Cambrian Arthropod

Mollisonia is an extinct genus of Cambrian arthropod. 4 species had been described from North America and China. Studies suggest it is a basal member of Chelicerata, a group which includes horseshoe crabs and arachnids.

<span class="mw-page-title-main">Fezouata Formation</span> Geological formation in Morocco

The Fezouata Formation or Fezouata Shale is a geological formation in Morocco which dates to the Early Ordovician. It was deposited in a marine environment, and is known for its exceptionally preserved fossils, filling an important preservational window beyond the earlier and more common Cambrian Burgess shale-type deposits. The fauna of this geological unit is often described as the Fezouata biota, and the particular strata within the formation which exhibit exceptional preservation are generally termed the Fezouata Lagerstätte.

<i>Stanleycaris</i> Extinct genus of basal hurdiid radiodonts

Stanleycaris is an extinct genus of hurdiid radiodont from the Cambrian. The type species is Stanleycaris hirpex. Stanleycaris was described from the Stephen Formation near the Stanley Glacier and Burgess Shale locality of Canada, as well as Wheeler Formation of United States. A second species, S. qingjiangensis is known from the Qingjiang biota of China. The genus was characterized by the rake-like frontal appendages with robust inner spines.

<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>Vachonisia</i> Extinct genus of Devonian organisms

Vachonisia is a Devonian marrellomorph known from the Lower Devonian Hunsrück Slate. It grows in a similar fashion to the other Hunsruck marrellomorph, Mimetaster, and is closely related to the Silurian Xylokorys. It is known from 20 specimens; its whole body is covered by a shield-like carapace.

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

Austromarrella is an extinct genus of marrellomorph arthropod known from the Middle Cambrian of Australia.

<i>Furca</i> (genus) Extinct genus of arthropods

Furca is an extinct genus of marrellomorph arthropod known from the Sandbian stage of the Czech Republic, with a single currently described species, Furca bohemica. A tentative additional species, "Furca mauretanica": was proposed for specimens discovered in Morocco, but this species remains a nomen nudum until formally published, and probably belongs in a new separate genus.

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

Hurdiidae is an extinct cosmopolitan family of radiodonts, a group of stem-group arthropods, which lived during the Paleozoic Era. It is the most long-lived radiodont clade, lasting from the Cambrian period to the Devonian period.

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

The Artiopoda is a grouping of extinct arthropods that includes trilobites and their close relatives. It was erected by Hou and Bergström in 1997 to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomorpha. Trilobites, in part due to abundance of findings owing to their mineralized exoskeletons, are by far the best recorded, diverse, and long lived members of the clade. Other members, which lack mineralised exoskeletons, are known mostly from Cambrian deposits.

This list of fossil arthropods described in 2019 is a list of new taxa of trilobites, fossil insects, crustaceans, arachnids and other fossil arthropods of every kind that are scheduled to be described during the year 2019, as well as other significant discoveries and events related to arthropod paleontology that are scheduled to occur in the year 2019.

<span class="mw-page-title-main">Vicissicaudata</span> Extinct group of artiopods

Vicissicaudata is an unranked group of artiopods, containing Cheloniellida, Aglaspidida and several other genera outside these groups like Sidneyia and Emeraldella.

<i>Tomlinsonus</i> Extinct genus of marrellomorph

Tomlinsonus is an extinct genus of marrellomorph arthropod known from the Late Ordovician (Katian) Kirkfield Formation of Ontario, Canada. It is a member of Marrellida, and closely related to Mimetaster.

<i>Zhenghecaris</i> Genus of enigmatic Cambrian arthropod

Zhenghecaris is an extinct genus of enigmatic arthropods from the Lower Cambrian Maotianshan Shales, tentatively classified as a hurdiid (peytoiid) radiodont, and originally as a thylacocephalan. The genus contains a single species, Zhenghecaris shankouensis, known from several specimens mostly preserving the carapace and eyes. These specimens measure roughly 15 cm (5.9 in) in width, making it one of the largest thylacocephalans, behind Ostenocaris, Dollocaris and Ainiktozoon, as well as the earliest since all other thylacocephalans are Ordovician or younger. Better preserved fossils show that it was more similar to the domed sclerites of radiodonts such as Cambroraster, with two lateral spine processes on either side of the carapace, the eyes apparently fitting into the posterior notches. Additional isolated sclerites from the Chengjiang have been described as the lateral sclerites of Zhenghecaris due to their broad similarity to the P-elements of hurdiids (peytoiids), and because of their similar construction, ornamentation, and possession of two-pronged lateral spine processes. It has also been classified conservatively as Arthropoda incertae sedis, as the fragmentary remains cannot confidently be classified further due to the lack of associated appendages of trunk elements.

References

  1. Rak, Štĕpán; Ortega-Hernández, Javier; Legg, David A. (2011). "A revision of the Late Ordovician marrellomorph arthropod Furca bohemica from Czech Republic". Acta Palaeontologica Polonica. doi: 10.4202/app.2011.0038 .
  2. 1 2 3 4 5 6 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.
  3. Legg, D.A. (2015-09-30). "The morphology and affinities of Skania fragilis (Arthropoda) from the middle Cambrian Burgess Shale". Bulletin of Geosciences: 509–518. doi: 10.3140/bull.geosci.1532 . ISSN   1802-8225.
  4. Haug, Joachim T.; Castellani, Christopher; Haug, Carolin; Waloszek, Dieter; Maas, Andreas (2012). "A Marrella-like arthropod from the Cambrian of Australia: A new link between "Orsten"-type and Burgess Shale assemblages". Acta Palaeontologica Polonica. 58 (3): 629–639. doi: 10.4202/app.2011.0120 .
  5. Legg, David (2016). "A new marrellid arthropod from the Ordovician of Wales". Acta Palaeontologica Polonica. 61. doi: 10.4202/app.00246.2016 . ISSN   0567-7920.
  6. Legg, David A. (2016-02-27). "An acercostracan marrellomorph (Euarthropoda) from the Lower Ordovician of Morocco". The Science of Nature. 103 (3): 21. Bibcode:2016SciNa.103...21L. doi:10.1007/s00114-016-1352-5. ISSN   1432-1904. PMID   26922777.