Lichida

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Lichida
Temporal range: Furongian–Frasnian
Terataspis grandis e.JPG
Terataspis grandis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Lichida
Moore, 1959
Families [1]
Akantharges Akantharges.TheFossilTrade.jpg
Akantharges

Lichida is an order of typically spiny trilobite that lived from the Furongian to the Devonian period. [2] These trilobites usually have 8–13 thoracic segments. [1] Their exoskeletons often have a grainy texture or have wart or spine-like tubercles. Some species are extraordinarily spiny, having spiny thoracic segments that are as long or longer than the entire body, from cephalon (head) to pygidium (tail). The sections of the pygidia are leaf-like in shape and also typically end in spines.

Contents

The order is divided into two families, Lichidae, and Lichakephalidae. [1] Some experts group the families of the closely related order Odontopleurida within Lichida, too, whereupon the family is then divided into three superfamilies, Dameselloidea, containing the family Damesellidae, Lichoidea, containing the families Lichidae and Lichakephalidae, and Odontopleuroidea, containing the family Odontopleuridae.

Lichids are some of the largest trilobites, with the second and third largest trilobites ( Uralichas hispanicus , and Teratapsis grandis ) being in the order [3]

Taxa traditionally placed within Lichida

Parvilichas marochii Parvilichas marochii.jpg
Parvilichas marochii

As mentioned earlier, the order Lichida is divided into two families.

Lichidae

Lichakephalidae

Cladogram

Lichidae
Lichakephalidae

Related Research Articles

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<span class="mw-page-title-main">Pygidium</span> Posterior body part or shield of crustaceans and some other arthropods

The pygidium is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is composed of fused body segments, sometimes with a tail, and separated from thoracic segments by an articulation.

<i>Dalmanites</i> Extinct genus of trilobites

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<i>Paradoxides</i> Extinct genus of trilobites

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<i>Balcoracania</i> Extinct family of trilobites

Balcoracania dailyi is a small trilobite of the family Emuellidae. Its fossils have been found in south Australia and Antarctica.

<span class="mw-page-title-main">Olenellina</span> Extinct suborder of trilobites

Olenellina is a suborder of the order Redlichiida of trilobites that occurs about halfway during the Lower Cambrian, at the start of the stage called the Atdabanian. Olenellina are arguably the earliest trilobites in the fossil record as members of Redlichiina, although Ptychopariida and Eodiscina follow soon after. The suborder died out when the Lower Cambrian passed into the Middle Cambrian, at the end of the stage called Toyonian. A feature uniting the Olenellina is the lack of rupture lines in the headshield, which in other trilobites assist the periodic moulting, associated with arthropod growth. Some derived trilobites have lost facial sutures again, but all of these are blind, while all Olenellina have eyes.

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

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<i>Terataspis</i> Lichid trilobite genus

Terataspis is a comparatively huge, 60 centimetre long lichid trilobite genus from the Early Devonian, about 397 million years ago. It lived in a shallow sea in what is now New York State and Ontario. No whole specimens have been found, only disarticulated fragments of its exoskeleton, but enough fragments have been found to allow researchers to form reconstructions of the whole animal. The genus only contains one species, T. grandis.

<span class="mw-page-title-main">Ronald Pearson Tripp</span> British paleontologist (1914–2001)

Ronald Pearson Tripp FRSE was a British palaeontologist specializing in trilobites. He was self-taught in palaeontology and became an authority on the taxonomy of the trilobite order Lichida and the trilobite family Encrinuridae.

<i>Acimetopus</i> Extinct genus of trilobites

Acimetopus Rasetti, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943), Order Agnostida Salter (1864). It lived during the Botomian stage. = late Lower Cambrian Stage 4 ; the upper Botomian boundary corresponds to base of the Middle Cambrian, Miaolingian Series and Wuliuan stage.

<i>Nevadella</i> Extinct genus of trilobites

Nevadella is an extinct genus of trilobites, fossil marine arthropods, with species of average size. It lived during the late Atdabanian stage, which lasted from 530 to 524 million years ago during the early part of the Cambrian Period.

<i>Fallotaspis</i> Cambrian Period genus of trilobites

Fallotaspis is a genus of redlichiid trilobites found in Early Cambrian-aged strata of the United States and Morocco.

<span class="mw-page-title-main">Odontopleurida</span> Order of trilobites

Odontopleurida is an order of very spinose trilobites closely related to the trilobites of the order Lichida. Some experts group the Odontopleurid families, Odontopleuridae and Damesellidae, within Lichida. Odontopleurids tend to have convex, bar-shaped cephalons, and lobed, knob-shaped glabella that extend to, or almost to the anterior margin. Many, if not almost all odontopleurids have long spines that are derived either from the margins of the exoskeleton, or from granular or tubercular ornamentation, or both. Many odontopleurids are so spinose so as to be described as having "spines on (their) spines." Odontopleurids have 8 to 13 thoracic segments, with Odontopleuridae odontopleurids having no more than 10, and Damesellidae odontopleurids having no more than 13. The pygidium tends to be very small, and invariably has long spines emanating from it in all known genera.

<span class="mw-page-title-main">Holmiidae</span> Family of trilobites

Holmiidae is a family of trilobites, that lived during the Lower Cambrian (Atdabanian). The Holmiidae is a diverse family of eight genera containing at least 17 species. It includes some of the earliest trilobites of Baltica. Holmiidae occur throughout Baltica and Western Laurentia, and also in Morocco.

<i>Peachella</i>

Peachella is an extinct genus of trilobites, fossil marine arthropods, with species of average size. It lived during the Toyonian stage, 516 to 513 million years ago, in what is today the southwestern United States. It can easily be distinguished from other trilobites by its club-like genal spines.

<i>Eopeachella</i>

Eopeachella is an extinct genus of trilobites, fossil marine arthropods, with species of probably small size, entire, articulate specimens have not yet been found. It lived during the Toyonian stage, in what is today the South-Western United States. Eopeachella angustispina is the only known species in this genus.

<i>Emigrantia</i>

Emigrantia is an extinct genus of trilobites, fossil marine arthropods, of small to average size. It lived during the Toyonian stage, in what is today the South-Western United States. Emigrantia can easily be distinguished from other trilobites by the sturdy but not inflated genal spines, that are attached at midlength of the cephalon, in combination with effaced features of the raised axial area of the head shield.

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

Eodiscina is trilobite suborder. The Eodiscina first developed near the end of the Lower Cambrian period and became extinct at the end of the Middle Cambrian. Species are tiny to small, and have a thorax of two or three segments. Eodiscina includes six families classified under one superfamily, Eodiscoidea.

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

Cyclopygidae is a family of asaphid trilobites from the Ordovician. Cyclopygids had an extratropical distribution, and there is evidence that they lived in darker parts of the water column. Cyclopygids are characterized by enlarged eyes, with a wide angle of view, both horizontal and vertical, reminiscent of the eyes of dragonflies. These typically touch the glabella directly on the side. Cyclopygids all lack genal spines, but Symphysops carries a forward directed frontal spine on the glabella. It is presumed that at least the members of the genus Pricyclopyge swam upside down and had bioluminescent organs on the third thorax segment. Cyclopygids had between 7 and 5 thorax segments, a wide and stout axis, and short side lobes.

References

  1. 1 2 3 S. M. Gon III (January 1, 2008). "Pictorial guide to the order Lichida" . Retrieved October 24, 2013.
  2. H. B. Whittington (2002). "Lichidae (Trilobita): morphology and classification". Journal of Paleontology . 76 (2): 306–320. doi:10.1666/0022-3360(2002)076<0306:LTMAC>2.0.CO;2. JSTOR   1307144.
  3. "The World's Largest Trilobites".

Further reading