A new motile animal with implications for the evolution of axial polarity from the Ediacaran of South Australia

Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One ap...

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Bibliographic Details
Published in:Evolution & development 2024-11, Vol.26 (6), p.e12491-n/a
Main Authors: Evans, Scott D., Hughes, Ian V., Hughes, Emily B., Dzaugis, Peter W., Dzaugis, Matthew P., Gehling, James G., García‐Bellido, Diego C., Droser, Mary L.
Format: Article
Language:English
Subjects:
Animals
axial polarity
Biological Evolution
Body Patterning
Chirality
Ediacara Biota
Fossils
Fossils - anatomy & histology
motility
New species
Phylogeny
Polarity
South Australia
symmetry
Trace fossils
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Summary:Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity. Here, we describe a new taxon, Quaestio simpsonorum gen. et sp. nov. from the Ediacaran of South Australia. Quaestio is reconstructed with a thin external membrane connecting more resilient tissues with anterior‐posterior polarity, left‐right asymmetry and tentative evidence for dorsoventral differentiation. Associated trace fossils indicate an epibenthic and motile lifestyle. Our results suggest that Quaestio was a motile eumetazoan with a body plan not previously recognized in the Ediacaran, including definitive evidence of chirality. This organization, combined with previous evidence for axial patterning in a variety of other Ediacara taxa, demonstrates that metazoan body plans were well established in the Precambrian. We report the discovery of Quaestio simpsonorum gen. et sp. nov., a motile, bilaterally symmetrical Ediacaran fossil, with the oldest documented macroscopic, left‐right differentiation. Combined with axial polarity observed in the totality of the Ediacara Biota, this suggests the establishment of major metazoan body plans in the Precambrian.
ISSN:1520-541X
1525-142X
1525-142X
DOI:10.1111/ede.12491