Modularity and overcompensatory growth in Ediacaran rangeomorphs demonstrate early adaptations for coping with environmental pressures

Kenchington, Charlotte G.; Dunn, Frances S.; Wilby, Philip R.. 2018 Modularity and overcompensatory growth in Ediacaran rangeomorphs demonstrate early adaptations for coping with environmental pressures. Current Biology, 28 (20). 3330-3336.e2. https://doi.org/10.1016/j.cub.2018.08.036

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Official URL: http://dx.doi.org/10.1016/j.cub.2018.08.036

Abstract/Summary

The first known diverse, complex, macroscopic benthic marine ecosystems (late Ediacaran, ca. 571–541 Ma) were dominated by the Rangeomorpha, an enigmatic group of extinct frondose eukaryotes that are candidate early metazoans [1, 2]. The group is characterized by a self-similar branching architecture that was most likely optimized for exchange, but nearly every other aspect of their biology is contentious [2, 3, 4]. We report locally enhanced, aberrant growth (“eccentric branching”) in a stalked, multifoliate rangeomorph—Hylaecullulus fordi n. gen., n. sp.—from Charnwood Forest (UK), confirming the presence of true biological modularity within the group. Random branches achieve unusually large proportions and mimic the architecture of their parent branch, rather than that of their neighbors (the norm). Their locations indicate exceptional growth at existing loci, rather than insertion at new sites. Analogous overcompensatory branching in extant modular organisms requires the capacity to orchestrate growth at specific sites and occurs most frequently in response to damage or environmental stress, allowing regeneration toward optimum morphology (e.g., [5, 6, 7]). Its presence in rangeomorphs indicates a hitherto unappreciated level of control to their growth plan, a previously unrecognized form of morphological plasticity within the group, and an ability to actively respond to external physical stimuli. The trait would have afforded rangeomorphs resilience to fouling and abrasion, partially accounting for their wide environmental tolerance, and may have pre-adapted them to withstand predation, weakening this argument for their extinction. Our findings highlight that multiple, phylogenetically disparate clades first achieved large size through modularity.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.cub.2018.08.036
ISSN:	09609822
Date made live:	03 Jan 2019 15:49 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/521950

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.cub.2018.08.036

ISSN:

09609822

Date made live:

03 Jan 2019 15:49 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/521950