Peytoia

P. nathorsti. Credit: Jun111 on the Wikimedia Commons.

*Peytoia* is an extinct genus of hurdiid radiodont that lived in Canada and Poland during the Middle Cambrian.

## History

*Peytoia nathorsti* and *Laggania* were named in the same paper by Walcott (1911), with the former based on mouthparts Charles Walcott had believed were the body of a jellyfish and the latter would be sunken into the former by Simon Conway Morris (1978). Harry Whittington and Derek Briggs (1985) mistook the remains as anomalocaridid, creating the combination *Anomalocaris nathorsti*; in 2011, morphological evidence would suggest a split of the two as valid genera.

*Peytoia infercambriensis* was named by Lendzion (1975), with the specific epithet meaning "Lower Cambrian". However, it was first given the name *Pomerania* (a romanticization of Pomorze, Poland) *infercambriensis*, which was later found to be preoccupied by an ammonoid. It is known from one specimen from the Kościerzyna borehole (4.8 kilometers down from drillcore material), Cambrian Stage 3 of the Zawiszyn Formation. It is older than the Chenjiang biota based on being from the *Fallotaspis* Zone.

## Description

*P. infercambriensis* was interpreted as having 11 thoracic segments and a chelicera of a *Leanchoilia*-like arthropod. This would come into scrutiny as it was identified as anomalocaridid and later reinterpreted as the base of an elongate appendage with the body of an indeterminate arthropod. Because of this, *P. infercambriensis* was initially treated as a leanchoiliid, but is now lumped in this genus due to similarity. Of the Greater Phyllopod bed in the Burgess Shale, *Peytoia* makes up 0.21% of the fauna, with 108 specimens recorded. *P. infercambriensis* bears frontal appendages with at least 18 segments, long and straight ventral spines and minute serrations at the anterior edge that may form setae bases. It is unknown if the ventral spines were paired like related taxa. It's mouth consists of a ring of 32 lobes around an opening in the center divided into 4 quadrants, with larger lobes at the squared edges. 2 short points on each corner as possible anchors to the body or oral arms. The initial identification as a jellyfish is now seen as impossible at worst or dubious at best, since known remains share no traits, and no jellyfish have a true hole in the center of their bodies. Regardless, this initial interpretation was accepted for a long time. The appendage F, dubbed and originally referred to *Sidneyia* by Walcott, are generally accepted as the frontal appendages of *P. nathorsti*; these were initially interpreted as a giant, chimeric Cambrian radiodont.

## Classification

*P. infercambriensis* may be a transition from *"Anomalocaris" pennsylvanica* and *P. nathorsti*. It is quite similar to tamisiocaridids. It is traditionally referred to as a hurdiid related to *Hurdia*. Pates et al. (in the naming of *Utaurora*) find:

## Paleoecology

*Peytoia infercambriensis* likely sifted through fine sediment, if it's ventral spines truly possessed setae. The genus was initially envisioned as an apex predator as related to *Anomalocaris*, but further research has disproved this. It has also been suggested to filter water. The Burgess Shale is a fossil site from the Canadian mountains of British Columbia. Most of it's fossils were formed by sudden mudslides, which flattened and sometimes distorted individuals postmortem. The sediment here bore oxygen that reduces trace fossils and animal burrows. The fauna is a diverse assemblage of lobopods, annelids, radiodonts, arthropods, molluscs and even chordates, many of which are stem-groups or incertae sedis.

## Gallery

**Credit: Junn111 on the Wikimedia Commons.****Credit: Junn111 on the Wikimedia Commons.****Credit: Junn111 on the Wikimedia Commons.****Credit: Junn111 on the Wikimedia Commons.**Appendage F.
## References

* https://en.wikipedia.org/wiki/Peytoia\_infercambriensis
* https://en.wikipedia.org/wiki/Peytoia\_nathorsti
* https://gq.pgi.gov.pl/article/view/9290/7833
* https://en.wikipedia.org/wiki/Fossils\_of\_the\_Burgess\_Shale
* https://en.wikipedia.org/wiki/Burgess\_Shale
* https://www.amazon.ca/Wonderful-Life-Burgess-Nature-History/dp/039330700X
* https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2021.2093