Cotyledion Explained

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]

See also

• Dinomischus
• Siphusauctum

Notes and References

1. Clausen . S. B. . Hou . X. G. . Bergström . J. . Franzén . C. . The absence of echinoderms from the Lower Cambrian Chengjiang fauna of China: Palaeoecological and palaeogeographical implications . 10.1016/j.palaeo.2010.01.001 . Palaeogeography, Palaeoclimatology, Palaeoecology . 294 . 3–4 . 133–141 . 2010 . 2010PPP...294..133C .
2. McMenamin, M. A. S. . 2013 . Breakthrough on the Cambrian Explosion . BioScience . 63 . 10 . 834–835 . 10.1525/bio.2013.63.10.14. free .
3. 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. . A sclerite-bearing stem group entoproct from the early Cambrian and its implications . 10.1038/srep01066 . Scientific Reports . 3 . 1066 . 2013 . 23336066. 3548229. 2013NatSR...3E1066Z .
4. McMenamin, M. A. S. . 2013 . Breakthrough on the Cambrian Explosion . BioScience . 63 . 10 . 834–835 . 10.1525/bio.2013.63.10.14. free .