PROFILPELAJAR.COM

Cotyledion; Temporal range: Cambrian Stage 3 PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Stem group:	Entoprocta
Genus:	†Cotyledion; Luo et Hu, 1999
Species:	†C. tylodes
Binomial name
	†Cotyledion tylodes; Luo et Hu, 1999

Cotyledion tylodes is an extinct, stalked filter-feeder known from the Chengjiang lagerstatten. The living animal reached a couple of centimetres in height, and bore a loose scleritome of ovoid sclerites. Its interpretation has been controversial, and it has been previously identified as a carpoid echinoderm,^[1] or as a stem group echinoderm.^[2] C. tylodes is now classified as a stem group entoprocta based on new fossils that clearly show a U-shaped gut and a crown of tentacles.^[3] This entoproct interpretation of Cotyledion, however, has been questioned by Mark McMenamin, who considers it best interpreted as a stem group echinoderm based on the morphology of its stem sclerites.^[4]

References

^ Clausen, S. B.; Hou, X. G.; Bergström, J.; Franzén, C. (2010). "The absence of echinoderms from the Lower Cambrian Chengjiang fauna of China: Palaeoecological and palaeogeographical implications". Palaeogeography, Palaeoclimatology, Palaeoecology. 294 (3–4): 133–141. Bibcode:2010PPP...294..133C. doi:10.1016/j.palaeo.2010.01.001.
^ McMenamin, M. A. S. (2013). "Breakthrough on the Cambrian Explosion". BioScience. 63 (10): 834–835. doi:10.1525/bio.2013.63.10.14.
^ Zhang, Z.; Holmer, L. E.; Skovsted, C. B.; Brock, G. A.; Budd, G. E.; Fu, D.; Zhang, X.; Shu, D.; Han, J.; Liu, J.; Wang, H.; Butler, A. N.; Li, G. (2013). "A sclerite-bearing stem group entoproct from the early Cambrian and its implications". Scientific Reports. 3: 1066. Bibcode:2013NatSR...3E1066Z. doi:10.1038/srep01066. PMC 3548229. PMID 23336066.
^ McMenamin, M. A. S. (2013). "Breakthrough on the Cambrian Explosion". BioScience. 63 (10): 834–835. doi:10.1525/bio.2013.63.10.14.