Namapoikia Explained

Namapoikia rietoogensis is among the earliest known animals to produce a calcareous (probably aragonite^[1]) skeleton.^[2] Known from the Ediacaran period, before the Cambrian explosion of calcifying animals, the long-lived organism grew up to a metre in diameter and resembles a colonial sponge.^[3] It was an encruster, filling vertical fissures in the reefs in which it originally grew.^[4]

The fossil was first found in the Omkyk Member of the Nama Group from Rietoog in southern Namibia, in association with other calcifying fossils, Cloudina and Namacalathus.

Its mineralogy and accretionary style has been compared with that of the Lophotrochozoans,^[5] though its unfamiliar morphology suggests a stem-group or deeper affiliation to this group.^[6]

It grew in spurts, first emplacing an organic skeleton, then filling this in with aragonite.^[7]

See also

• Ediacaran biota
• Namacalathus
• Cloudina
• List of Ediacaran genera

Notes and References

1. Zhuravlev, A.Y., Wood, R.A., and Penny, A.M. (2015). Ediacaran skeletal metazoan interpreted as a lophophorate. Proc. R. Soc. B 282, 20151860. Available at: http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2015.1860.
2. Science. 1 June 2007. 316. 5829. 10.1126/science.1137284. Seawater Chemistry and Early Carbonate Biomineralization. Susannah M. Porter. 1302. 17540895. 2007Sci...316.1302P. 27418253.
3. Wood. Rachel A.. Rachel Wood (geologist). John P. Grotzinger. John P. Grotzinger. J. A. D. Dickson. Proterozoic Modular Biomineralized Metazoan from the Nama Group, Namibia. Science. 28 June 2002. 296. 5577. 2383–2386. 10.1126/science.1071599. 12089440. 2002Sci...296.2383W. 9515357 .
4. Grotzinger, J.P. . John P. Grotzinger. Watters, W. A. . Knoll, A. H. . 2000 . Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia . Paleobiology . 26 . 3 . 334–359 . 10.1666/0094-8373(2000)026<0334:CMITSR>2.0.CO;2 . 52231115 .
5. 4650157. 2015. Zhuravlev. A. Y.. Ediacaran skeletal metazoan interpreted as a lophophorate. Proceedings of the Royal Society B: Biological Sciences. 282. 1818. 20151860. Wood. R. A.. Penny. A. M.. 10.1098/rspb.2015.1860. 26538593.
6. Zhuravlev . A. Yu. . Liñán . E. L. . Vintaned . J. A. Gámez . Debrenne . F. . Fedorov . A. B. . 2012 . New finds of skeletal fossils in the terminal Neoproterozoic of the Siberian Platform and Spain . 10.4202/app.2010.0074 . Acta Palaeontologica Polonica . 57 . 205–224 . free .
7. 10.1098/rspb.2017.1938. Substrate growth dynamics and biomineralization of an Ediacaran encrusting poriferan. Proceedings of the Royal Society B: Biological Sciences. 285. 1870. 20171938. 2018. Wood. Rachel. Penny. Amelia. 29321296. 5784191.