''Eopeachella'' 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 ...

trilobites 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 ...

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

arthropods Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, oft ...

, with species of probably small size (largest 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 ...

) long), entire, articulate specimens have not yet been found. It lived during the

Toyonian Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commissi ...

stage (Upper ''Olenellus''-zone), in what is today the South-Western United States. ''Eopeachella angustispina'' 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 ...

Etymology

''Eopeachella'' is named for its early occurrence compared to and presumed closeness to '' Peachella''. The species epithet ''angustispina'' refers to the slender genal spines compared to those in the species of ''Peachella''.

Description

Only the cephalon of ''Eopeachella'' is known. It is a small sized biceratopsid trilobite, that exhibits the effaced cephalic features that are typical for that family. ''Eopeachella'' has short, stout genal spines, which are somewhat inflated at base and terminate in pointed tips and inflated lateral cephalic borders.
The cephalon is semi-circular in outline with short, strongly inflated rounded spines. The central area of the cephalon (or

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...

) is elongated, reaching the anterior border, and hourglass shaped. Its features are effaced, showing only shallow furrows.

Differences with some other Biceratopsinae

Some other Biceratopsinae share some of the most eye catching features of ''Eopeachella''. These differ however in the following characteristics. '' Biceratops nevadensis'', '' Emigrantia'' and ''Peachella'' all have more extremely effaced cephalic features. ''Biceratops'' lacks genal spines. In ''Emigrantia'' the genal spines are longer than the cephalon and attach halfway down its side (or lateral margin). ''Peachella'' has club-like genal spines. The genal spine bases and lateral cephalic border are also inflated in ''Paranephrolenellus inflatus'', but this species differs from ''Eopeachella'' in having clearly visible glabellar furrows, and strongly divergent ocular lobes.

Relations with other biceratopsids

''Eopeachella'' first occurs in the fossil record before both ''Peachella'' species, although it overlaps with ''P. iddingsi''. The thick, tapered, genal spines and shallow but clear glabellar furrows of ''E. angustispina'' are intermediate between the ''Peachella'' species that have club-like strongly inflated genal spines and more radically effaced cephalic features and ancestral olenelloidea.

Distribution

Specimens of ''Eopeachella angustispina'' have been collected from the Delamar Mountains in Lincoln County, Nevada, Lincoln County, Nevada.

Habitat

''E. angustispina'' was probably a marine bottom dweller, like all Olenellina.

Ecology

''E. angustispina'' occurs together with '' Olenellus nevadensis'', '' Peachella iddingsi'' and ''

Bristolia ''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 (Upper ''Olenellus''-zone) shelf deposits across the southwestern US, ...

sp.''.

References

{{Taxonbar, from=Q5381834 Cambrian trilobites of North America Fossil taxa described in 2009 Redlichiida genera Biceratopsidae Cambrian genus extinctions