Resserops

Resserops; Temporal range: Atdabanian/Botomian PreЄ Є O S D C P T J K Pg N [1]
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Trilobita
Order:	Redlichiida
Suborder:	Redlichiina
Superfamily:	Redlichioidea
Family:	Saukiandidae
Subfamily:	Resseropinae
Genus:	Resserops; Richter & Richter, 1940 [2]
Species:	R. resserianus
Binomial name
	Resserops resserianus; Richter & Richter, 1940
Synonyms
	Perrector (Resserops) resserianus

Last updated May 05, 2019

Resserops is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the middle of the Atdabanian or the early part of the Botomian stage,^[1] which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. It has been found in Spain and southern Morocco. It can be recognised by the sabre-like spines of the headshield that are a smooth continuation of the frontal edge, and the enlarged spines on the 9th segment of the thorax.

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. The totality of fossils is known as the fossil record.

An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.

Distribution

Lower Cambrian of Spain^[3] and Southern Morocco (Daguinaspis and Resserops-zone near Amouslek, Ouijane and Tiout).^[4]

Taxonomy

The Treatise^[3] considers Resserops and Richterops subgenera of Perrector, which name was proposed by Hupé in the same publication as Resserops and Richterops, but appears above it and thus has preference. Later publications use Resserops and Richterops however as separate genera.

Richterops is an extinct genus of trilobite arthropods. The genus lived during the middle of the Atdabanian or the early part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the second half of the Lower Cambrian. It has been found in southern Morocco. It can be recognised by the long spines of the headshield that are a smooth continuation of the frontal edge, and the enlarged spines on the 11th segment of the thorax.

Description

As with most early trilobites, Resserops has an almost flat exoskeleton, that is only thinly calcified, and has crescent-shaped eye ridges. As a representative of the Redlichiina suborder, the headshield (or cephalon) has sutures where the exoskeleton ruptures to assist in moulting. The cephalon is approximately ovate, more than twice as wide as long. There is no space between the raised axis (or glabella) and the raised ridge (or anterior border) that defines the contour of the cephalon (in jargon: the preglabellar field is absent). The eye ridges are large, extend outward and arch backward near their tips. The cephalon carries massive sabre-like relatively short spines (or genal spines) that are a smooth continuation of the anterior border. The genal spines are connected at about half of the length of the cephalon (or are well-advanced). The tips of the genal spines are approximately as far out as their base. The thorax has 12 segments, the 9th segment (counted from the front) carries large spines at its tips, longer than the genal spines and longer than the thorax axis, extending about one pygidial length behind the body. The tailshield (or pygidium) has a smooth border, is large for a redlichiida, (about 60% of the length of the cephalon), both the axis and pleural regions of the pygidium have about 6 recognisable segments.^[3]

In biology, moulting, or molting, also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body, either at specific times of the year, or at specific points in its life cycle.

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References

1 2 Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology. 364: 560. Retrieved 2008-01-12.
↑ Richter, Rudolf; Richter, Emma (1940). "Studien im Paläozoikum der Mittelmeer-Länder, 5: Die Saukianda-Stufe von Andalusien, eine fremde Fauna im europäischen Ober-Kambrium". Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft. 450: 1–81.
1 2 3 Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostina, Order Redlichiida. 1997
↑ Zhang, W.-T.; Chen, P.-J.; Palmer, A.R. (2003). Biostratigraphy of China. Beijing: Science Press.

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[Sepkoski-1] 1 2 Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology. 364: 560. Retrieved 2008-01-12.

[2] Richter, Rudolf; Richter, Emma (1940). "Studien im Paläozoikum der Mittelmeer-Länder, 5: Die Saukianda-Stufe von Andalusien, eine fremde Fauna im europäischen Ober-Kambrium". Abhandlungen der Senckenbergischen Naturforschenden Gesellschaft. 450: 1–81.

[Whittington_et_al-3] 1 2 3 Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostina, Order Redlichiida. 1997

[4] Zhang, W.-T.; Chen, P.-J.; Palmer, A.R. (2003). Biostratigraphy of China. Beijing: Science Press.