Plexus ricei
Extinct worm-like organism from the Ediacarian period
From Wikipedia, the free encyclopedia
Plexus ricei is an enigmatic fossil animal known from South Australia that has a problematic taxonomy due to its fossils not resembling any other known taxon that is part of the Ediacaran biota.[2]
| Plexus ricei Temporal range: Ediacaran, ~ | |
|---|---|
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| Artist's interpretation of P. ricei | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | incertae sedis |
| Genus: | †Plexus Joel, Droser & Gehling, 2014[1] |
| Species: | †P. ricei |
| Binomial name | |
| †Plexus ricei Joel, Droser & Gehling, 2014 | |
Etymology
The genus name, Plexus, means "braided" in Latin, a reference to its braided appearance. The specific name, ricei, is a reference to Dennis Rice, one of the field assistants at the South Australian Museum, who helped excavate numerous specimens of the fossil.[2]
Morphology
The fossilized organism is tubular and worm-like, with a body divided into rounded segments, making it look similar to a tapeworm with its long, laterally flattened body.[3][2] Its body appears to be bilaterally symmetric. The individuals range in size from 5 to 80 centimeters long and 5 to 20 millimeters wide.[3] The organism is composed of a rigid median tubular structure and a fragile outer tubular wall.[2]
Relations
While Plexus ricei appears to be bilaterally symmetric, it is unsure if this organism is a member of Bilateria, although animals that appear to have bilateral symmetry existed at the time.[2] However, Plexus ricei does not resemble any of the other animals from the time period, such as Charnia, Dickinsonia, or Kimberella, bilateral symmetry or not. No other Ediacarian animal has such a long, flattened body, meaning that this organism could belong to an entirely new classification of these extinct animals, or be an ancestor of the complex bilaterians that existed during the Cambrian.