TY - JOUR
T1 - Three-dimensional reconstructions of the putative metazoan Namapoikia show that it was a microbial construction
AU - Mehra, Akshay
AU - Watters, Wesley A.
AU - Grotzinger, John P.
AU - Maloof, Adam C.
N1 - Funding Information:
ACKNOWLEDGMENTS. We thank C. Husselmann for granting us access to Driedoornvlakte Farm. At the Geological Survey of Namibia, G. Schneider and J. Eiseb granted us permits for working in Namibia and assisted us with the export permitting process, respectively. At MIT, B. Ren performed grinding and imaging, and T. Mason created an early reconstruction, of sample B. All of Situ Studio, but especially B. Samuels, were instrumental in the development of GIRI. A. Tasistro Hart and R. Bartolucci provided invaluable assistance in the field. At the Smithsonian, M. Florence dedicated his time to help locate Inozoan specimens for study, while D. Erwin kindly gave permission to destructively analyze the A. perforata sample. R. Shapiro generously provided us with a sample of F. cooperi for reconstruction. Our morphological analyses benefited from discussions with A. Getraer, B. Howes, R. Manzuk, and E. Geyman. We thank J. Strauss for feedback on the manuscript and A. Knoll and two anonymous reviewers for their thoughtful critique and input. This work was supported by NSF Earth Sciences Grant 1028768 to A. Maloof and by funding from the Princeton Tuttle Invertebrate Fund.
Publisher Copyright:
© 2020 National Academy of Sciences. All rights reserved.
PY - 2020/8
Y1 - 2020/8
N2 - 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.
AB - 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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U2 - 10.1073/PNAS.2009129117
DO - 10.1073/PNAS.2009129117
M3 - Article
C2 - 32747528
AN - SCOPUS:85089787922
SN - 0027-8424
VL - 117
SP - 19760
EP - 19766
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 33
ER -