Uncus dzaugisi
| Uncus dzaugisi Temporal range:
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| Genus: | †Uncus Hughes et al., 2024
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| Species: | †U. dzaugisi
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| Binomial name | |
| Uncus dzaugisi Hughes et al., 2024
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Uncus dzaugisi is an extinct species of animal which lived 560 to 550 Ma during the late Ediacaran of Southern Australia. It is likely the earliest definitive ecdysozoan known.[1] It is the only member of the genus Uncus.
Discovery and name
[edit]Fossil material of Uncus was discovered at the Ediacara Member at Nilpena Ediacara National Park in 2024, totaling at 82 specimens.[1]
The generic name Uncus is derived directly from the Latin word Uncus, meaning "hooked", in reference to the shape of many well preserved specimens. The specific name dzaugisi is the Latinisation of the surname of Mary, Matthew and Peter dzaugisi, in honor of their contributions to fieldwork at the Nilpena Ediacara National Park, from which the fossil material comes from.[1]
Description
[edit]Uncus is a soft-bodied, smooth cylindrical organism with a sharp margin, growing from 6 to 30 millimeters in overall length. All specimens are also noted for having varying degrees of curvature to them, with one end being wider than the other end, with the wider possibly being the posterior end as seen in other ecdysozoans. Unlike most other Ediacaran organisms, it possibly had a sturdy external membrane, as evidenced by 77 out of the 82 specimens showing little to no deformation.[1]
The sharpness of the edges also shows that Uncus was free from the organic mats that covered the seabeds of Ediacaran Australia, showing that it may have most likely been motile, unlike sessile organisms which are preserved having softer margins due to the organic mat growing onto them. This is further supported with the existence of the ichnogenus Multina on one of the fossil beds were Uncus specimens were found, which it is proposed to be the maker of. Several specimens have also been found overlaying other Ediacaran organisms, such as felled Funisia, and even the feeding traces of other motile organisms such as Dickinsonia.[1]
Affinity
[edit]The sturdy membrane around the organism is possibly evidence of an early cuticle. This in addition to its body shape and motile lifestyle suggests Uncus was a member of Ecdysozoa, with possible relations to nematoids.[1] Many molecular clocks have estimated the origin of Ecdysozoa in the Ediacaran,[2][3][4] but no difinitive ecdysozoans have been found. If Uncus is indeed an ecdysozoan, it would be the first Ediacaran example found and would finally bridge the gap between the early bilaterians of the Ediacaran and the early ecdysozoans like arthropods and priapulids of the Cambrian.
References
[edit]- ^ a b c d e f Hughes, Ian V.; Evans, Scott D.; Droser, Mary L. (18 November 2024). "An Ediacaran bilaterian with an ecdysozoan affinity from South Australia". Current Biology. doi:10.1016/j.cub.2024.10.030.
- ^ Reis, Mario dos; Thawornwattana, Yuttapong; Angelis, Konstantinos; Telford, Maximilian J.; Donoghue, Philip C.J.; Yang, Ziheng (21 November 2024). "Uncertainty in the Timing of Origin of Animals and the Limits of Precision in Molecular Timescales". Current Biology. doi:10.1016/j.cub.2015.09.066.
- ^ Rehm, Peter; Borner, Janus; Meusemann, Karen; von Reumont, Björn M.; Simon, Sabrina; Hadrys, Heike; Misof, Bernhard; Burmester, Thorsten (December 2011). "Dating the arthropod tree based on large-scale transcriptome data". Molecular Phylogenetics and Evolution. 61 (3): 880–887. doi:10.1016/j.ympev.2011.09.003.
- ^ Howard, Richard J.; Giacomelli, Mattia; Lozano-Fernandez, Jesus; Edgecombe, Gregory D.; Fleming, James F.; Kristensen, Reinhardt M.; Ma, Xiaoya; Olesen, Jørgen; Sørensen, Martin V.; Thomsen, Philip F.; Wills, Matthew A.; Donoghue, Philip C. J.; Pisani, Davide (July 2022). "The Ediacaran origin of Ecdysozoa: integrating fossil and phylogenomic data". Journal of the Geological Society. 179 (4). doi:10.1144/jgs2021-107.