Platyceratidae

Platyceratidae is an extinct family of Paleozoic sea snails, marine gastropod mollusks. This family may belong in the Patellogastropoda or the Neritimorpha.[2]

Platyceratidae Temporal range: Middle Ordovician–Permian[1][2] PreꞒ Ꞓ O S D C P T J K Pg N
Conical platyceratid gastropod (Palaeocapulus acutirostre) attached to a crinoid (Mississippian of Ohio)
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Superfamily:	†Platyceratoidea Hall, 1879
Family:	†Platyceratidae Hall, 1879

Platyceratids are known for the complex symbiotic relationships they had with crinoids.[3] Platyceratids are thought to have been parasitic on crinoids, either drilling into the stomach to steal the crinoid's food in a form of kleptoparasitism or drilling into the anal sac to feed on the gonads or the hindgut.[3][4] Previous authors have suggested that platyceratids were commensalists which fed on crinoid fecal matter without harming the crinoid, but more recent studies have shown that platyceratids did have a negative effect on their crinoid hosts as would be expected if they were actively parasitic.[5]. It has been suggested that the large spines present on many species of crinoids served to deter predators who might damage or harm the crinoid in an effort to feed on the platyceratid snails infesting it.[4]

This is the only family in the superfamily Platyceratoidea.

Genera

• Platyceras Conrad, 1840 - type genus
• Palaeocapulus Grabau & Shimer, 1909

References

1. Wagner, P. J. (2004). "Phylogenetic Relationships of the Earliest Anisostrophically Coiled Gastropods". Smithsonian Contributions to Paleobiology. 88: 1–152. doi:10.5479/si.00810266.88.1.
2. Sutton, M. D.; Briggs, D. E. G.; Siveter, D. J.; Siveter, D. J. (2006). "Fossilized soft tissues in a Silurian platyceratid gastropod". Proceedings of the Royal Society B: Biological Sciences. 273 (1590): 1039. doi:10.1098/rspb.2005.3403. PMC 1560260. PMID 16600878.
3. Baumiller, T. K. (2003). "Evaluating the interaction between platyceratid gastropods and crinoids; a cost-benefit approach". Palaeogeography, Palaeoclimatology, Palaeoecology. 201 (3–4): 199–209. Bibcode:2003PPP...201..199B. doi:10.1016/S0031-0182(03)00625-4.
4. Syverson, Valerie J. P.; Brett, Carlton E.; Gahn, Forest J.; Baumiller, Tomasz K. (21 March 2018). "Spinosity, regeneration, and targeting among Paleozoic crinoids and their predators". Paleobiology. 44 (2): 290–305. doi:10.1017/pab.2017.38.
5. Rollins, Harold B.; Brezkinski, David K. (9 October 2007). "Reinterpretation of crinoid-platyceratid interaction". Lethaia. 21 (3): 207–217. doi:10.1111/j.1502-3931.1988.tb02072.x.

Cross-section of a Lower Carboniferous crinoid with an in situ parasitic platyceratid gastropod.