Pywackia

Pywackia is a contentious Cambrian fossil that has been interpreted as the earliest (total group) Bryozoan, and the only representative of that phylum in the Cambrian period.^[1] Its Bryozoan credentials have been called into question,^[2] but the octocoral alternative is equally unconvincing, and there are reasons to suggest a position in the Stenolaemata stem lineage.^[3] Finally, the skeletal microstructure is consistent with a cnidarian affinity, but insufficient to support a close affinity with any modern subgroup.^[4]

Pywackia Temporal range: Late Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
Artist's restoration
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	incertae sedis
Genus:	†Pywackia
Species:	†P. baileyi
Binomial name
†Pywackia baileyi Landing in Landing et al., 2010

References

1. Landing, E.; English, A.; Keppie, J. D. (2010). "Cambrian origin of all skeletalized metazoan phyla--Discovery of Earth's oldest bryozoans (Upper Cambrian, southern Mexico)". Geology. 38 (6): 547. Bibcode:2010Geo....38..547L. doi:10.1130/G30870.1.
2. Taylor, P. D.; Berning, B. R.; Wilson, M. A. (2013). "Reinterpretation of the Cambrian 'Bryozoan' Pywackia as an Octocoral". Journal of Paleontology. 87 (6): 984. Bibcode:2013JPal...87..984T. doi:10.1666/13-029. S2CID 129113026.
3. Ed Landing; Jonathan B. Antcliffe; Martin D. Brasier; Adam B. English (2015). "Distinguishing Earth's oldest known bryozoan (Pywackia, late Cambrian) from pennatulacean octocorals (Mesozoic—Recent)". Journal of Paleontology. 89 (2): 292–317. Bibcode:2015JPal...89..292L. doi:10.1017/jpa.2014.26. S2CID 131609198.
4. Hageman, Steven J.; Vinn, Olev (2023). "Late Cambrian Pywackia is a cnidarian, not a bryozoan: Insights from skeletal microstructure". Journal of Paleontology: 1–12. doi:10.1017/jpa.2023.35.