''Marocconus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

from a well-known class of

fossil A fossil (from Classical Latin , ) 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 ...

marine

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s, the

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

s. It is still debated if it lived at the very end of the Lower Cambrian or at the very beginning of the Middle Cambrian. ''Marocconus notabilis'' is the only known species in this genus (i.e. the genus is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

Taxonomy

''Marocconus'' replaces ''Cephalopyge'' Geyer, 1988, which is a

junior homonym In biology, a homonym is a name for a taxon that is identical in spelling to another such name, that belongs to a different taxon. The rule in the International Code of Zoological Nomenclature is that the first such name to be published is the se ...

of '' Cephalopyge'' Hanel, 1905, a

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...

. ''Cephalopyge'' however, is still widely used for this trilobite, and the new name ''Marocconus'' has only been mentioned one time in the scientific literature.

Distribution

''Marocconus notabilis'' is known from the latest Lower Cambrian or earliest Middle Cambrian of Morocco
Jbel Wawrmast Formation
Anti-Atlas Mountains).Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997

Ecology

''Marocconus notabilis'' occurs in the same layers a ''Cambropallas telesto''.

Description

Like all Agnostida, ''Marocconus'' is diminutive and the headshield (or

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino ...

) and tailshield (or

pygidium The pygidium (plural pygidia) 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 com ...

) are of approximately the same size (or

isopygous The pygidium (plural pygidia) 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 compo ...

) and outline. Like all Weymouthiidae, it lacks eyes and rupture lines (or sutures). The cephalon is subcircular except for the straight posterior. The external surface of the cephalon is smooth, convex, and is hanging over an extremely narrow border. The central raised area of the cephalon (or glabella) is evident on the internal mold by a clear defining furrow, long triangular in outline (about 1⅓× as long as the maximum width), with rounded tips and only one transverse furrow (SO). The occipital ring (LO) is short (measured along the length of the animal), and hangs over the posterior margin. The thorax has three segments, like all other Weymouthiidae for which the thorax is known. The pygidium is also externally smooth, and convex. The internal mold shows a long triangular axis, narrower than the glabella (about 1⅓× as long as the maximum width), with rounded tips extending to the posterior margin, and without visible segmentation. The pygidium has no border furrow.

References

{{Taxonbar, from=Q6772283 Weymouthiidae Agnostida genera Cambrian trilobites Fossils of Morocco Animals described in 1988