Hylaecullulus

{{Use dmy dates|date=July 2022}} {{Speciesbox | fossil_range = {{fossil range|561|557}} Ediacaran | genus = Hylaecullulus | parent_authority = Kenchington, Dunn, & Wilby, 2018 | species = fordi | authority = Kenchington, Dunn, & Wilby, 2018 }}

'''''Hylaecullulus fordi''''', also described as '''dumbbells''', is an extinct species of Ediacaran petalonamid whose fossils were found in the Charnwood Forest of Leicestershire, England. It serves as an important rangeomorph because of its multifoliate anatomy. Its overall body plan is similar to that of a goblet, from which its name, ''Hylaecullulus'', alongside its common name of dumbbell, is derived from.<ref name="PDF1">{{cite journal | doi=10.1016/j.cub.2018.08.036 | title=Modularity and Overcompensatory Growth in Ediacaran Rangeomorphs Demonstrate Early Adaptations for Coping with Environmental Pressures | year=2018 | last1=Kenchington | first1=Charlotte G. | last2=Dunn | first2=Frances S. | last3=Wilby | first3=Philip R. | journal=Current Biology | volume=28 | issue=20 | pages=3330–3336.e2 | pmid=30293718 | s2cid=52933769 | doi-access=free | bibcode=2018CBio...28E3330K }}</ref><ref name="PDF2">{{cite web | url=https://metadata.bgs.ac.uk/geonetwork/srv/api/records/7260bc26-c83f-5469-e054-002128a47908 | title=Reflectance Transformation Imaging files of Hylaecullulus fordi, a new species of rangeomorph from the Bradgate Formation (Ediacaran) of Charnwood Forest, Leicestershire, UK }}</ref>

==Etymology== The name ''Hylaecullulus fordi'' is derived from the Ancient Greek words {{lang|grc-Latn|hylaeos}}, which means 'from the woods' (in reference to its occurrence within Charnwood Forest), and {{lang|grc-Latn|cullulus}}, which means "small goblet". The name of the type species, "fordi", was given to honour Trevor Ford, who made important contributions to the Ediacaran fauna.<ref name="PDF1"/>

==Discovery==

''Hylaecullulus fordi'' was discovered in the hilly tract of Charnwood Forest in 2018 by a team led by Charlotte G. Kenchington. This team found six well-preserved fossils at the top of the Bradgate Formation of the Maplewell Group. All of them had fossilised in epirelief (positive relief) impressions with the lateral view of the animal visible. Although two specimens out of the six fossils found were poorly preserved, they were still assigned to the genus. After the discovery of these fossils, master molds were made of them; these molds are housed within the British Geological Survey, while the holotypes are kept ''in situ''.<ref name="PDF1"/>

==Description== ''Hylaecullulus fordi'' is a multifoliate rangeomorph consisting of a holdfast and a similarly sized crown, connected by a straight, proportionally long and narrow stem of uniform width. The stem is longer than the crown. The holdfast consists of multiple concentric rings and up a triangular shape where it meets the stem.<ref name="PDF1"/> The crown has a sub-circular (nearly circular) outline and is multifoliate—having multiple unrestrained folia (leaves) that all emanate from a single point at the tip of the stem. The fossils had both unfurled and furled folia, showing distal inflation.<ref name="PDF1"/><ref name="PDF2"/>

The primary and secondary branches were typically displayed, furled, radiating, unconstrained, and proximally inflated (with unfurled branches being locally present in some specimens). Unlike the primary and secondary branches, the tertiary branches were constrained, and showed only slight radiation and distal inflation.<ref name="PDF1"/> The folia and the primary and secondary branches of the crown may manifest "eccentric branches" at any point along their length that conform to the branching pattern of their host branch, unlike other rangeomorphs that conform to the branching pattern of their neighboring folia.<ref name="PDF1"/><ref name="PDF2"/>

===Measurements=== The heights of the known specimens (which are measured from the base of the stem) range from {{convert|7.6|–|37.6|cm|in}}. The diameter of the disc ranges from {{convert|2.7|–|27|cm|in}}, increasing in proportion with the total height.<ref name="PDF1"/>

===Comparison to other rangeomorphs=== [[File:Primocandelabrum.jpg|thumb|180px|left|The Ediacaran fossil, ''Primocandelabrum'', superficially resembles ''Hylaecullulus'' in anatomy, although has a much simpler holdfast and a more triangular crown.<ref name="PDF1"/>]] ''Hylaecullulus fordi'' fossils are distinguished from other rangeomorphs because of its multifoliate nature, a trait only shared with ''Bradgatia'' and ''Primocandelabrum''. These two taxa also occur alongside ''H. fordi'' fossils on Bed B of the Bradgate Formation, although they both deviate a little from ''Hylaecullulus''. ''Bradgatia'' has a similar multifoliate anatomy, although it lacks a proper stem and instead has a small, bulb-shaped holdfast.<ref name="PDF1"/> The architecture of the branches within ''Bradgatia'' are also distinct from ''Hylaecullulus'', since the folia seen in ''Bradgatia'' are unfurled and show signs of radiation from all resolvable orders of its branching. ''Primocandelabrum'' only superficially resembles ''Hylaecullulus'' because it possesses a more anatomically simple holdfast alongside a straight and proportionally shorter stem. The bushy crown of ''Primocandelabrum'' is distinct from the crown of ''H. fordi'' because of its notably triangular outline and branches that are coarser and in the shape of a candelabrum.<ref name="PDF1"/>

==Significance for Ediacaran fauna and rangeomorphs== ''H. fordi'' indicates greater architectural complexity and modular organization in rangeomorph body plans, highlighting the importance of modularity when evolving to have a larger body plan in phylogenetically disparate taxa and clades.<ref name="PDF1"/> The evolution of eccentric branch growths indicate their ability to respond to physical, external stimuli and recover from damage, giving them considerable environmental tolerance.<ref name="PDF1"/><ref name="PDF2"/>

==See also== * List of Ediacaran genera

==References== {{Reflist}}

Category:Petalonamae Category:Ediacaran Category:Ediacaran life Category:Aquatic animals Category:Ediacaran Europe Category:Fossil taxa described in 2018