Archaeaspis

Last updated

Archaeaspis
Temporal range: Late Atdabanian
Archaeaspis hupei recon.jpg
Reconstruction of A. hupei
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Trilobita
Order:
Redlichiida
Suborder:
Olenellina
Superfamily:
Fallotaspidoidea
Family:
Archaeaspididae
Genus:
Archaeaspis

Repina in Khomentovskii and Repina, 1965 [1] non ArchaeaspisIvantsov, 2001 [2] = ArchaeaspinusIvantsov, 2007
Species
  • A. hupeiRepina in Khomentovskii and Repina, 1965 (Type) [1]
  • A. nelsoniLieberman, 2002 [1]
  • A. macropleuronLieberman, 2002 [1]

Archaeaspis is an extinct genus of redlichiid trilobites. It lived during the late Atdabanian stage, [3] which lasted from 521 to 514 million years ago during the early part of the Cambrian Period. The first specimens were first found in Siberia, where they were originally thought to have been endemic. Later, though, more specimen were found in the Inyo Mountains in Southern California. [4] An Ediacarian proarticulatan was given the same name, Archaeaspis Ivantsov, 2001. This is however a junior homonym. The name Archaeaspis Repina in Khomentovskii and Repina, 1965, for the trilobite has priority. The new valid name for the proarticulate is Archaeaspinus Ivantsov, 2007. [5]

Contents

Etymology

The genus name is the combination of the Ancient Greek ἀρχαῖος (archaīos) meaning "ancient" and ἀσπίς (aspis) meaning "shield". The names of the species have the following derivations.

Distribution

Description

As with most early trilobites, Archaeaspis has an almost flat exoskeleton that is only thinly calcified, and has crescent-shaped eye ridges. As part of the Olenellina suborder, Archaeaspis lack dorsal sutures. The superfamily Fallotaspidoidea, to which Archaeaspis belongs can be distinguished from all other Olenellina by features of the cephalon and in particular the glabella. The glabella tapers forward. The frontal lobe of the glabella (because it is counted from the back, it is numbered L4) is as long as the most backward lobe (L0), less than in the other Olenellina. The eye ridges (or ocular lobes) contact, but do not merge with, the entire frontal margin of the glabella. [7] In Archaeaspis the frontal lobe of the glabella (L4) does not contact the anterior border furrow, but is connected with it by a ridge at midline (called plectrum). There is an obvious ridge that crosses the area between the ocular lobe and the glabella backward and slightly outward at approximately 10° (called interocular ridge). [1]

Species key

1The ridge bordering the head shield (or anterior border) right in front of the sides of the glabella is at most 1¼× as wide as the most backward lobe of the glabella (occipital ring or L0). The anterior border is rounded across. The eye ridge (or ocular lobe) is directed backwards and slightly outwards (the line between the posterior tip of the ocular lobe and the junction of the interior margin and the frontal lobe of the glabella has an angle of at most 20° with the midline). → 2
-The anterior border approximately 1½× as wide as L0. The anterior border is flattened dorsally. The tangent of the ocular lobe is directed backwards and substantially outward at 35°- 45°.
→ Archaeaspis hupei
2The lateral spines on the third segment of the thorax (T3) are comparable in size to those of neighboring segments. The distance between the anterior cephalic border and the frontal lobe of the glabella (or preglabellar field) is ¼-¾× the length of L0. The segments of the thorax axis are smooth or have a faint node.
→ Archaeaspis macropleura
-T3 carries long pleural spines that extend the length of the thorax, and the spine on T4 is almost absent. The preglabellar field is ¾-1¼× the length of L0. The thorax axis carries distinct nodes.
→ Archaeaspis nelsoni [1]

Related Research Articles

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

Olenellus is an extinct genus of redlichiid trilobites, with species of average size. It lived during the Botomian and Toyonian stages (Olenellus-zone), 522 to 510 million years ago, in what is currently North-America, part of the palaeocontinent Laurentia.

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

Nevadia is an extinct genus of redlichiid trilobites, with species of average size. It lived during the Atdabanian stage, which lasted from 530 to 524 million years ago, in what are today Western Canada, the Western United States, and Mexico.

<i>Olenelloides</i>

Olenelloides armatus is an extinct, small sized olenelloid redlichiid trilobite arthropod. It lived during the later part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. The most conspicuous feature is the hexagonal head shield that carries 6 ray-like spines..

<i>Wanneria</i>

Wanneria is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. Wanneria walcottana is the only known species in this genus.

Elliptocephala is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from the later part of the Tommotian to the upper Botomian. Elliptocephala can easily be confused with Ellipsocephalus, a trilobite genus of the Ptychopariida order.

Cirquella is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Atdabanian stage, in the former continent Laurentia.

<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>Nephrolenellus</i>

Nephrolenellus is an extinct genus of trilobite, fossil marine arthropods, of relatively small size. Currently two species are attributed to it. Nephrolenellus lived at the end of the Lower Cambrian. Species are known from the Great Basin of California, Nevada and Arizona, with one specimen from Canada.

<i>Mesonacis</i>

Mesonacis is an extinct genus of trilobite that lived during the Botomian, found in North-America, and the United Kingdom. Some of the species now regarded part of Mesonacis, have previously been assigned to Angustolenellus or Olenellus (Angustolenellus). Angustolenellus is now regarded a junior synonym of Mesonacis.

<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">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>Biceratops</i>

Biceratops is an extinct genus of olenelloid redlichiid trilobites, of average size, with the largest specimen 8 centimetres or 3.1 inches long, not including the huge pleural spines of the 3rd segment of the thorax. It lived during the Toyonian stage, in what is today the South-Western United States. Biceratops can easily be distinguished from other members of Biceratopsidae by the absence of genal spines, in combination with effaced features of the raised axial area of the head shield, that is bordering the two horn-like projections that carry the eyes. Biceratops nevadensis is the only known species in this genus.

<span class="mw-page-title-main">Olenelloidea</span> Extinct superfamily of trilobites

The Olenelloidea are a superfamily of trilobites, a group of extinct marine arthropods. They lived during the late Lower Cambrian and species occurred on all paleocontinents.

Mesolenellus is an extinct genus of trilobites that lived during the lower Cambrian (Botomian), found in Greenland and Spitsbergen.

Lochmanolenellus is an extinct genus of trilobites, fossil marine arthropods, with one small species, L. mexicana. It lived during the Botomian stage (Olenellus-zone), 522–513 million years ago, in the South-West of the former continent of Laurentia, in what are today Mexico, and the South-Western United States.

<i>Bristolia</i>

Bristolia is an extinct genus of trilobite, fossil marine arthropods, with eight or more small to average size species. It is common in and limited to the Lower Cambrian shelf deposits across the southwestern US, which constitutes part of the former paleocontinent of Laurentia.

<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.

Bolbolenellus is an extinct genus of trilobites, fossil marine arthropods, with five species attributed to it currently. It can be easily distinguished from all other trilobites by the combination of the absence of dorsal sutures in the head shield like all Olenellina, and a distinctly bulbous frontal lobe (L4) of the raised axial area in the head called glabella. The species lived at the end of the Lower Cambrian.

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

The ”Fallotaspidoidea” are a superfamily of trilobites, a group of extinct marine arthropods. It lived during the Lower Cambrian (Atdabanian) and species occurred on all paleocontinents except for the Gondwana heartland. A member of this group, Profallotaspis jakutensis, has long been the earliest known trilobite, but recently the redlichiid Lemdadella has been claimed as occurring even earlier.

References

  1. 1 2 3 4 5 6 7 8 9 10 Lieberman, B.S. (2002). "Phylogenetic analysis of some basal early Cambrian Trilobites, the biogeographic origins of the Eutrilobites, and the timing of the Cambrian radiation" (PDF). Journal of Paleontology. 76 (4): 692–708. doi:10.1666/0022-3360(2002)076<0692:paosbe>2.0.co;2. Archived from the original (PDF) on 2011-08-12. Retrieved 2012-08-14.
  2. ↑ The Rise of Animals: Evolution and diversification of the Kingdom Animalia. Baltimore: The Johns Hopkins University Press. 2007. ISBN   978-0-8018-8679-9.
  3. ↑ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology. 364: 1–560. Archived from the original on 2006-09-05. Retrieved 2008-01-12.
  4. ↑ "Archaeaspis macropleuron Lieberman, 2002". Archived from the original on 2008-05-16. Retrieved 2008-04-29.
  5. ↑ Ivantsov, A. Yu (2007). "Small Vendian transversely Articulated fossils". Paleontological Journal. 41 (2): 113–122. Bibcode:2007PalJ...41..113I. doi:10.1134/S0031030107020013. ISSN   0031-0301. S2CID   86636748.
  6. ↑ Palmer, A.R.; Repina, L.N. (1993), "Through a Glass Darkly: Taxonomy, Phylogeny and Biostratigraphy of the Olenellina", The University of Kansas Paleontological Contributions, 3: 1–35
  7. ↑ Lieberman, B. S. (1998). "Cladistic analysis of the Early Cambrian olenelloid trilobites". Journal of Paleontology . 72: 59–78. Bibcode:1998JPal...72...59L. doi:10.1017/S0022336000024021. S2CID   86307339.
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.