# Peachella

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***Peachella*** is an [extinct](/source/Extinct) [genus](/source/Genus) of [trilobites](/source/Trilobita), [fossil](/source/Fossil) marine [arthropods](/source/Arthropoda), with species of average size (about 3.5 centimetres or 1.4 inches long). It lived during the [Toyonian](/source/Toyonian) stage (Upper *Olenellus*-zone), , in what is today the southwestern United States. It can easily be distinguished from other trilobites by its club-like [genal spines](http://www.trilobites.info/glossary.htm).[1][2]

## Etymology

*Peachella* is named in honor of [Benjamin Neeve Peach](/source/Ben_Peach), a British geologist. The species epithet *brevispina* is derived from [Latin](/source/Latin) and means 'short spine'. *P. iddingsi* was named in honor of [Joseph P. Iddings](/source/Joseph_P._Iddings), an accomplished American geologist.

## Origin

The earliest occurrence of the ancestral *[Eopeachella angustispina](/source/Eopeachella)* 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.[2]

## Description

As with most early trilobites, *Peachella* has an almost flat [exoskeleton](/source/Exoskeleton), 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](/source/Trilobite#Cephalon). *Peachella* is an average sized [biceratopsid](/source/Biceratopsidae) trilobite, that exhibits the strongly effaced cephalic features that are typical for a [clade](/source/Clade) 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](/source/Bolbolenellus)*). *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 [glabella](/source/Cephalon_(arthropod_head))) is elongated, reaching the anterior border, but its features are strongly effaced, almost showing no furrows. The frontal 14[2] or 15[1] segments (or [prothorax](/source/Trilobite#Thorax)) can readily be distinguished from the terminal 9 to 11 (forming the [opisthothorax](/source/Trilobite#Thorax)). 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](/source/Trilobite#Pygidium)) is very small and subquadrate in shape.[1][2][3]

### Differences with some other Biceratopsinae

*[Biceratops nevadensis](/source/Biceratops)* and *[Emigrantia](/source/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.[2]

## Distribution

Specimens of *Peachella brevispina* have been collected from the middle [Peachella iddingsi-zone](/source/Trilobite_zone#Subdivision_of_the_Olenellus-zone) of the Dublin Hills, Eagle Mountain, and Nopah Range, all in [Inyo County](/source/Inyo_County,_California) [35°48′N 116°12′W](https://geohack.toolforge.org/geohack.php?params=35_48_N_116_12_W), California. Further specimens were found in the Chief Range and Highland Range, in [Lincoln County](/source/Lincoln_County,_Nevada), Nevada.

*Peachella iddingsi*, occurs in the lower half of the [Peachella iddingsi-zone](/source/Trilobite_zone#Subdivision_of_the_Olenellus-zone) of the Marble Mountains and Providence Mountains ([San Bernardino County](/source/San_Bernardino_County,_California)), 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](/source/Clark_County,_Nevada)), Toiyable Range ([Lander County](/source/Lander_County,_Nevada)), and Prospect Peak ([Eureka County](/source/Eureka_County,_Nevada)), Nevada.[2][4]

## Habitat

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

## Ecology

*P. brevispina* occurs together with *[Bristolia fragilis](/source/Bristolia)*, [*Olenellus nevadensis*](/source/Olenellus) and *P. iddingsi*. *P. iddingsi* occurs together with *Bristolia fragilis*, *Bristolia* aff. *fragilis* A, *Paranephrolenellus besti*, [*Mesonacis fremonti*](/source/Mesonacis), *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.[2]

## Key to the Species

1 Genal spines strongly inflated, blunt and club-like. Posterior margin of the cephalon straight or gradually arching forwards or backwards.→ 2 - Genal spines moderately inflated at base, pointed. Outer 1⁄3 of the posterior margin of the cephalon angling forward. → Eopeachella angustispina Webster, 2009 2 Basis of the inflated genal spines opposite the frontal half of the eyes. Macropleural spines of the 3rd thorax segment relatively long (at least 3⁄4× body length) and slender (width at midlength of the prothorax up to 1⁄3 of the axis), emerging from the thorax at approximately 45° or more perpendicular to the axis. → Peachella iddingsi (Walcott, 1884) - Basis of the inflated genal spines opposite the posterior half of the eyes. Macropleural spines of the 3rd thorax segment relatively short (at most 2⁄3× body length) and robust (width at midlength of the prothorax more than 1⁄2 of the axis), emerging from the thorax at approximately 35° or less perpendicular to the axis. → Peachella brevispina Palmer, 1979

## References

1. J.H. Stitt & R.L. Clark (1984). ["A Complete Specimen Of Peachella-Brevispina - An Unusual Olenellid Trilobite Arthropoda Olenellida From The Lower Cambrian Of California"](http://biostor.org/74445). *[Transactions of the San Diego Society of Natural History](/source/Transactions_of_the_San_Diego_Society_of_Natural_History)*. **20** (9): 145–150. [doi:10.5962/bhl.part.29003](https://doi.org/10.5962/bhl.part.29003)[dead link]

1. M. Webster (2009). "Ontogeny, Systematics, and Evolution of the effaced Early Cambrian trilobites *Peachella* Walcott, 1910 and *Eopeachella* new genus (Olenellidea)". *[Journal of Paleontology](/source/Journal_of_Paleontology)*. **83** (2): 197–218. [Bibcode:2009JPal...83..197W](https://ui.adsabs.harvard.edu/abs/2009JPal...83..197W). [doi:10.1666/08-106.1](https://doi.org/10.1666/08-106.1). [S2CID 85698638](https://api.semanticscholar.org/CorpusID:85698638)

1. H.B. Whittington et al. (1997). "Introduction, Order Agnostida, Order Redlichiida". *Treatise on Invertebrate Paleontology. Part O, Revised. Trilobita*

1. [The Paleobiology Database](https://paleodb.org/cgi-bin/bridge.pl?a=displayCollResults&taxon_no=19154&max_interval=Cambrian&country=United%20States&state=California&is_real_user=1&basic=yes&type=view&match_subgenera=1)

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Adapted from the Wikipedia article [Peachella](https://en.wikipedia.org/wiki/Peachella) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Peachella?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.