Peytoia

Source: Wikipedia, the free encyclopedia.

Peytoia
Temporal range: Cambrian Stage 3–Miaolingian
Fossil specimen of Peytoia nathorsti
Reconstruction of P. nathorsti
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: †Dinocaridida
Order: †Radiodonta
Family: †Hurdiidae
Genus: †Peytoia
Walcott, 1911
Type species
†Peytoia nathorsti
Walcott, 1911
Species
Synonyms
  • Laggania
    Walcott, 1911
  • Pomerania
    Lendzion, 1975 (preoccupied)
  • Cassubia
    Lendzion, 1977

Peytoia is a genus of

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.[1] Its two frontal appendages had long bristle
-like spines, it had no fan tail, and its short stalked eyes were behind its large head.

108 specimens of Peytoia are known from the Greater Phyllopod bed, where they comprise 0.21% of the community.[2]

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.[1]

Classification

Peytoia belongs to the clade Hurdiidae, and is closely related to the contemporary genus Hurdia.[3]

Peytoia contains two named species:

Wheeler and Marjum Formations of the United States,[4] and Peytoia infercambriensis from the Zawiszyn Formation of Poland.[1] Another species of Peytoia may be present in the Burgess Shale, represented by a single frontal appendage from the Tulip Beds locality.[5] A specimen regarded as Peytoia cf. nathorsti is known from the Balang Formation of China.[6]

History

Holotype oral cone of Peytoia nathorsti

The history of Peytoia is entangled with that of "

mineralized and unmineralized body parts; the oral cone (mouth) and frontal appendage were considerably harder and more easily fossilized than the delicate body.[7]

The first was a detached frontal appendage of Anomalocaris, described by

holothurian (sea cucumber). In 1978, Simon Conway Morris noted that the mouthparts of Laggania were identical to Peytoia, but interpreted this as indicating that Laggania was a composite fossil of Peytoia and the sponge Corralio undulata.[8] Later, while clearing what he thought was an unrelated specimen, Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a phyllocarid abdomen and the oral cone thought to be a jellyfish.[9][7] Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and frontal appendage represented one enormous creature.[7] Laggania and Peytoia were named in the same publication, but Conway Morris selected Peytoia as the valid name in 1978, which makes it the valid name according to International Commission on Zoological Nomenclature rules.[8][10]

Only specimen of Peytoia infercambriensis

The discovery that Anomalocaris, Laggania, and Peytoia represented parts of a single type of animal led to the synonymization of the three genera, with Peytoia nathorsti reclassified as Anomalocaris nathorsti.[11] Peytoia nathorsti was subsequently considered a junior synonym of Anomalocaris canadensis, while Laggania cambria became recognized as a distinct genus and species again,[12] but in 2012 it was determined that Anomalocaris canadensis had an oral cone with only three large plates, unlike that of Laggania cambria and Peytoia nathorsti with four, and Peytoia was once again recognized as valid, with Laggania its junior synonym.[10]

A second species,

Leanchoiliidae,[13] a family which now known as part of the unrelated megacheirans (great appendage arthropods). It was subsequently renamed Cassubia infercambriensis because the name Pomerania had already been used for an ammonoid.[14] C. infercambriensis was later recognized as a radiodont.[15] It was later determined that the specimen was a composite of a radiodont frontal appendage and the body of an unknown arthropod.[1] Due to the close similarity of the appendage to Peytoia nathorsti, C. infercambriensis was reassigned to Peytoia.[1]

Description

  • Comparison of the frontal appendages of Peytoia with other members of Hurdiidae
    Comparison of the frontal appendages of Peytoia with other members of Hurdiidae
  • Morphology and movement range of the frontal appendage of Peytoia nathorsti
    Morphology and movement range of the frontal appendage of Peytoia nathorsti
  • Oral cone of Peytoia nathorsti in comparison to Anomalocaris and Hurdia
    Oral cone of Peytoia nathorsti in comparison to Anomalocaris and Hurdia
  • Size diagram
    Size diagram

P. nathorsti had body length about 30 centimetres (12 in).[16] 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.[17] 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.[18] The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to Hurdia, Peytoia has less prominent setal blades.[19]

Phylogeny

Phylogenetic position of Peytoia within Panarthropoda, according to Pates et al. (2022).[20]

Ecology

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.[21]

See also

References

  1. ^
    S2CID 130745134
    .
  2. S2CID 53646959
    .
  3. S2CID 205237459
    .
  4. PMID 33552709
    .
  5. S2CID 86465719
    .
  6. S2CID 129212098
    .
  7. ^
    ISBN 0-393-02705-8
    .
  8. ^ a b Conway Morris, S. (1978). "Laggania cambria Walcott: A composite fossil". Journal of Paleontology. 52 (1): 126–131.
  9. ISBN 0-19-850256-7
    .
  10. ^
    doi:10.1007/s00114-012-0910-8
  11. JSTOR 2396268
    .
  12. S2CID 131622496
    .
  13. ^ Lendzion, Kazimiera (1975). "Fauna of the Mobergella zone in the Polish Lower Cambrian". Geological Quarterly. 19 (2): 237–242.
  14. ^ Lendzion, Kazimiera (1977). "Cassubia - a new generic name for Pomerania Lendzion, 1975". Geological Quarterly. 21 (1).
  15. doi:10.1111/j.1502-3931.1988.tb01749.x
    .
  16. PMID 30218075
    .
  17. S2CID 253633303
    .
  18. S2CID 236552819
    .
  19. S2CID 135388079
    .
  20. PMID 35135344
    .
  21. PMID 34284622
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Peytoia&oldid=1194170197"