''Notchia weugi'' is a species of enigmatic arthropod from the Weeks Formation of Utah. It is the only species in the genus ''Notchia''.

Description

''Notchia'' has a wide, featureless head shield with rounded genal angles and no eyes (whether the eyes are absent or just ventrally located is unclear). The trunk consists of 12

tergite A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior ...

s with the third being widest and the body width decreasing posterior of this point. The first tergite is mostly concealed under the head shield, with the rest seemingly overlapping each other. The rest of the tergites also appear quite similar, although the lattermost are somewhat longer. The

telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...

is rectangular, with four spines on its posterior end. Unusually, ''Notchia'' preserves digestive glands, these being represented by dark "blobs" on the fossil. Seven pairs are preserved, decreasing in length and complexity posteriorly. The two cephalic glands and the first trunk gland consist of two long branches, the first gland being thinner than the second and in turn the third. The anterior branch of each seems to further branch at its end, with the posterior being shorter and unbranched. The second to fourth trunk glands are rather similar in shape, being large and club-like. The fifth pair is only preserved via a "halo" on the fossil where the left gland would be, although this suggests it was similar to the rest.

Classification

''Notchia'' shares many similarities with various disparate clades, although none match it exactly. Strabopids seem similar, with their non- styliform telson and short cephalons, however ''Notchia'' differs in multiple aspects, including a lack of eyes, the shape of the body, and an unusual telson shape. ''

Sidneyia ''Sidneyia'' is an extinct marine arthropod known from fossils found from the Early to the Mid Cambrian of China and the Mid Cambrian Burgess Shale of British Columbia, Canada. Description Sidneyia size comparison.svg, Size comparison of ''Si ...

'' also appears similar, but it too does not resemble ''Notchia'' exactly, with the former having a tail fan and differing body shape. Interestingly, ''Notchia'' share similarities with some

chelicerate The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, ticks ...

s, such as a reduced first tergite, although no chelicerate so far has such a short cephalon or similar amounts of trunk segments. The digestive glands are also unusual, due to possessing two pairs of them alongside more simple structures like those of

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

Etymology

''Notchia'' derives from Notch Peak, one of the highest mountains in the

House Range The House Range is a north-south trending mountain range in Millard County, of west-central Utah. The House Range was named in 1859 by James H. Simpson. It was named by Simpson because "...of its well-defined stratification and the resemblan ...

where the fossil was found. The species name ''weugi'' honours Andries Weug, who donated the holotype for study.

References

{{Taxonbar, from=Q21215166 Cambrian arthropods of North America Enigmatic arthropod taxa Fossil taxa described in 2015