Three-dimensional reconstructions of the putative metazoan Namapoikia show that it was a microbial construction

TitleThree-dimensional reconstructions of the putative metazoan Namapoikia show that it was a microbial construction
Publication TypeJournal Article
Year of Publication2020
AuthorsMehra A, Watters WA, Grotzinger JP, Maloof AC
JournalPNAS
Volume117
Start Page19760
Issue33
Pagination19760-19766
Date Published08/2020
Other Numbers65Maloof
Abstract

Strata from the Ediacaran Period (635 million to 538 million years ago [Ma]) contain several examples of enigmatic, putative shell-building metazoan fossils. These fossils may provide insight into the evolution and environmental impact of biomineralization on Earth, especially if their biological affinities and modern analogs can be identified. Recently, apparent morphological similarities with extant coralline demosponges have been used to assign a poriferan affinity to Namapoikia rietoogensis, a modular encrusting construction that is found growing between (and on) microbial buildups in Namibia. Here, we present three-dimensional reconstructions of Namapoikia that we use to assess the organism’s proposed affinity. Our morphological analyses, which comprise quantitative measurements of thickness, spacing, and connectivity, reveal that Namapoikia produced approximately millimeter-thick meandering and branching/merging sheets. We evaluate this reconstructed morphology in the context of poriferan biology and determine that Namapoikia likely is not a sponge-grade organism.

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URLhttp://dx.doi.org/10.1073/pnas.2009129117
DOI10.1073/pnas.2009129117