Kingdom incertae sedis | Rank Genus | |
Similar Hiemalora, Nimbia occlusa, Aspidella, Nemiana, Cyclomedusa | ||
Arumberia is an enigmatic fossil from the Ediacaran period originally described from the Arumbera Sandstone, Northern Territory, Australia but also found in the Urals, East Siberia, England and Wales, Northern France, the Avalon Peninsula and India. Several morphologically different species are recognized.
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Description
Arumberia appears as a poorly-delimited series of fine parallel grooves arising from a single region or point. A typical description of Arumberia banksi is given in Pandey and Kumar (2009):
It consists of array of straight to gently curved parallel to subparallel ridges about 1 – 3 mm wide and separated by flat to gently concave furrows of 1 – 7 mm in width. Relief from ridge top to furrow bottom is less than 1mm. Ridge ranges in length from 1.5 cm to 14.5 cm. Generally the ridges are parallel, but they also bifurcate. Ridges are developed on plane and rippled surfaces.
Identity
The identity of Arumberia is controversial. Arumberia has been originally interpreted as a 5–20 cm high cup-like organism, apparently composed of flexible tissue, attached to the sea bottom by a blunt apex or, later, as a colonial organism made of flexible, thin-walled tubes tightly joined together through their length. Affinities with Ernietta, Conostichus, Pteridinium, Palaeoplatoda, Phyllozoon and Bergaueria and Chuaria have been conjectured. Spheroidal objects found along with Arumberia have also been interpreted as "dispersable stage" of Arumberia itself.
Conversely, a non biological interpretation has been put forward Experiments in fact reproduced Arumberia-like traces from flume experiments and from the flux of water around small objects. The absence of Arumberia-like structures after the Ediacaran period could be due to the unique properties of the microbial mat that covered the sea floor at the period. However, there is still debate, with recent analysis of Urals' Arumberia-like structures leaning towards a biological interpretation as an organism adapted to shallow water environments.