| Avalofractus Temporal range: 570–565 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓ Ediacaran | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | †Petalonamae |
| Class: | †Rangeomorpha |
| Genus: | †Avalofractus Narbonne et al. (2009) |
| Species: | †A. abaculus Narbonne et al., 2009 |
| Binomial name | |
| †Avalofractus abaculus Narbonne et al., 2009 | |
Avalofractus abaculus is a frond-like rangeomorph fossil described from the Ediacaran of the Trepassey Formation, Spaniard's Bay, Newfoundland.
Morphology
Avalofractus displays a strongly fractal body shape, with four levels of nearly perfectly self-similar, pinnate, alternate branches. It was about 5 cm long on average, with a 1 cm-diameter holdfast at the base of the frond. The stem length is from 1/3 to 1/2 that of the whole frond. It is quite similar to Rangea, even if with distinct morphological differences that justify the creation of a new genus (e.g. absence of subsidiary quilts, frond elements free to rotate independently instead of being attached to each other by a membrane).
A 2017 analysis of Avalofractus fossils found that the growth of the animal and its morphology was dependent on the amount of nutrient, suggesting that the phenotype of Ediacaran organisms was flexible in response to environmental conditions.
Distribution
In contrast with other rangeomorphs, which have wide distributions, Avalofractus seems to have been an endemic species, being known only from the Spaniard's Bay deposits.
Reproduction
It has been suggested that Avalofractus could have been capable of vegetative reproduction: loose fronds could have detached and grow, rather like a plant cutting. This could explain the mysterious lack of independent rangeomorph fronds smaller than 10 mm in the fossil record.
A previous suggestion that Avalofractus younger individuals were encased in a sheath-like structure has been later dismissed.
See also
References
- ^ Narbonne, G. M.; Laflamme, M.; Greentree, C.; Trusler, P. (2009). "Reconstructing a Lost World: Ediacaran Rangeomorphs from Spaniard's Bay, Newfoundland". Journal of Paleontology. 83 (4): 503. doi:10.1666/08-072R1.1.
- Hoyal Cuthill, Jennifer F.; Conway Morris, Simon (2017). "Nutrient-dependent growth underpinned the Ediacaran transition to large body size". Nature Ecology & Evolution. 1 (8): 1201–1204. Bibcode:2017NatEE...1.1201H. doi:10.1038/s41559-017-0222-7. PMID 29046572.
- Brasier, M. D.; Liu, A. G.; Menon, L.; Matthews, J. J.; McIlroy, D.; Wacey, D. (2013). "Explaining the exceptional preservation of Ediacaran rangeomorphs from Spaniard's Bay, Newfoundland: A hydraulic model". Precambrian Research. 231: 122. doi:10.1016/j.precamres.2013.03.013.
| Taxon identifiers | |
|---|---|
| Avalofractus abaculus | |
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