''Peachella'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 At ...

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 Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

, with species of average size (about long). 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 Commission on ...

stage (Upper ''Olenellus''-zone), , in what is today the southwestern United States. It can easily be distinguished from other trilobites by its club-lik
genal spines

Etymology

''Peachella'' is named in honor of

Benjamin Neeve Peach Benjamin Neeve Peach (6 September 1842 – 29 January 1926) was a British geologist. Life Peach was born at Gorran Haven in Cornwall on 6 September 1842 to Jemima Mabson and Charles William Peach, an amateur British naturalist and geologist. ...

, a British geologist. The species epithet ''brevispina'' is derived from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

and means 'short spine'. ''P. iddingsi'' was named in honor of

Joseph P. Iddings Joseph Paxson Iddings (January 21, 1857 – September 8, 1920) was an American geologist and petrologist. Biography Joseph Paxson Iddings was born in Baltimore, Maryland on January 21, 1857, the son of a wholesaler in Philadelphia. He received a ...

, an accomplished American geologist.

Origin

The earliest occurrence of the ancestral '' Eopeachella angustispina'' predates both ''Peachella'' species, its latest occurrence overlaps with ''P. iddingsi'', which, in turn overlaps with ''P. brevispina''. ''E. angustispina'' has thick, tapered, blunt, genal spines and shallow but clear glabellar furrows. This species therefore bridges the morphological gap between the derived ''Peachella'' species and earlier olenelloid relatives that possess ‘normal’ genal spines.

Description

As with most early trilobites, ''Peachella'' has an almost flat

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

, that is only thinly calcified. It also shares crescent-shaped eye ridges, but these rise above the exoskeleton. As part of the suborder Olenellina, ''Peachella'' lacks dorsal sutures. Like all other members of the superfamily Olenelloidea, the eye-ridges spring from the back of the frontal lobe (L4) of the central area of the cephalon, that is called

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 ...

. ''Peachella'' is an average sized biceratopsid trilobite, that exhibits the strongly effaced cephalic features that are typical for a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

within the subfamily Biceratopsinae. It has the enormous sickle-shaped pleural spines on the 3rd thoracal segment with the rest of the family Biceratopsidae (except for ''

Bolbolenellus ''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 ...

''). ''Peachella'' is unique in having short, wide, strongly inflated genal spines, with broadly rounded tips. The cephalon is semi-circular in outline with short, strongly inflated rounded spines. The central area of the cephalon (or

) is elongated, reaching the anterior border, but its features are strongly effaced, almost showing no furrows. The frontal 14 or 15 segments (or

prothorax The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on ea ...

) can readily be distinguished from the terminal 9 to 11 (forming the opisthothorax). The last segment of the prothorax may carry a large spine. The tips of the pleura are rounded, which is unlike the usual pointed terminations in other Olenellina. The 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 compo ...

) is very small and subquadrate in shape.

Differences with some other Biceratopsinae

'' Biceratops nevadensis'' and '' Emigrantia'' share extremely effaced cephalic features with ''Peachella''. ''Biceratops'' however lacks genal spines. In ''Emigrantia'' the genal spines are longer than the cephalon and attach halfway down its side (or lateral margin), instead of being short and bloated. ''Eopeachella'' has genal spines which are inflated only the basis, and the cephalic features are only moderately effaced.

Distribution

Specimens of ''Peachella brevispina'' have been collected from the middle Peachella iddingsi-zone of the Dublin Hills, Eagle Mountain, and Nopah Range, all in

Inyo County Inyo County () is a county in the eastern central part of the U.S. state of California, located between the Sierra Nevada and the state of Nevada. In the 2020 census, the population was 19,016. The county seat is Independence. Inyo County is o ...

, California. Further specimens were found in the Chief Range and Highland Range, in Lincoln County, Nevada.
''Peachella iddingsi'', occurs in the lower half of the Peachella iddingsi-zone of the Marble Mountains and Providence Mountains (

San Bernardino County San Bernardino County (), officially the County of San Bernardino, is a county located in the southern portion of the U.S. state of California, and is located within the Inland Empire area. As of the 2020 U.S. Census, the population was 2,181, ...

), Grapevine Mountains, Funeral Mountain, Emigrants Pass in the Nopah Range, Eagle Mountain, Resting Springs Range and Last Chance Range (all Inyo County), in California. ''P. iddlingsi'' also comes from Groom Range, Delamar Mountains, and Chief Range (all Lincoln County), the Desert Range and the Spring Mountains ( Clark County), Toiyable Range (

Lander County Lander County is a county in the U.S. state of Nevada. As of the 2020 census, the population was 5,734. Its county seat is Battle Mountain. History Lander County was created in 1862 as the result of a mining boom on the Reese River along the ...

), and Prospect Peak (

Eureka County Eureka County is a County (United States), county in the U.S. state of Nevada. As of the 2020 United States Census, 2020 census, the population was 1,855, making it the second-least populous county in Nevada. Its county seat is Eureka, Nevada, E ...

), Nevada.The Paleobiology Database
/ref>

Habitat

''Peachella'' species were probably marine bottom dwellers, like all Olenellina.

Ecology

''P. brevispina'' occurs together with '' Bristolia fragilis'', ''Olenellus nevadensis'' and ''P. iddingsi''. ''P. iddingsi'' occurs together with ''Bristolia fragilis'', ''Bristolia'' aff. ''fragilis'' A, ''Paranephrolenellus besti'', ''Mesonacis fremonti'', ''Olenellus nevadensis'', ''Olenellus'' aff. ''terminatus'', and the tops of the ranges of ''Eopeachella angustispina'' and ''Bristolia anteros''. The range of ''P. iddingsi'' coincides with the bottom of the range of ''P. brevispina'', and may even fully enclose it.

Key to the Species

References

{{Taxonbar, from=Q7157674 Cambrian trilobites Redlichiida genera Biceratopsidae