Peytoia

Extinct genus of radiodont

Peytoia is a genus of hurdiid radiodont, an early diverging order of stem group arthropods, that lived in the Cambrian period, containing two species, Peytoia nathorsti from the Miaolingian of Canada and Peytoia infercambriensis from Poland, dating to Cambrian Stage 3. Peytoia nathorsti and its junior synonym Laggania cambria played a major role in the discovery of the radiodont body plan. Initially interpreted as a jellyfish and a sea cucumber respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore Anomalocaris like appendages. Peytoia infercambriensis is the geologically oldest known radiodont species. The oral cone of Peytoia nathorsti has four large plates, similar to Hurdia, as compared to three in Anomalocaris. However, unlike Hurdia, the oral cone of Peytoia lacks inner rows of spines. The frontal appendages have 13 podomeres in their distal part, as is typical and likely ancestral for radiodonts. Like other hurdiid radiodonts, the frontal appendages have five blade like endites, which have short auxiliary spines. An intercalary podomere is present, separating the proximal and distal ends of the appendage. The appendages also have large medial spines, sometimes referred to as "gnathites", which face towards the opposite appendage. The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to Hurdia, Peytoia has less prominent setal blades.

Phylogenetic position of Peytoia within Panarthropoda, according to Pates et al. (2022).

It has been proposed that the frontal appendages of Peytoia were used to sift sediment for prey, however, some authors have considered this unlikely due to the small size and irregular spacing of the auxiliary spines. It has been alternatively proposed that Peytoia was a predator, using its appendages to capture slow moving, relatively large benthic prey.