Rebel matrix
| Rebel matrix | ||||||||||||
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Rebellatrix (No. 4, bottom right) |
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| Temporal occurrence | ||||||||||||
| late Indusian to early Olenekian ( Lower Triassic ) | ||||||||||||
| ~ 249.5 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Rebellatricidae | ||||||||||||
| Wendruff & Wilson , 2012 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Rebel matrix | ||||||||||||
| Wendruff & Wilson, 2012 |
Rebellatrix is a genus of bony fish belonging to the coelacanth order. The only species described so far is Rebellatrix divaricerca . Fossils of the species were found in Wapiti Lake Provincial Park , British Columbia in the Canadian Rockies and dated to the Lower Triassic . The holotype is an almost completely preserved specimen, 54 cm long with only parts of the head and the pair of fins missing. The paratypes are incomplete. Two (25.5 + 69 cm long) consist of a rear half of the body, a third of an isolated caudal fin.
The tail fin is forked in Rebellatrix and is therefore unique among the coelaceans. This characteristic "rebellious" against "normal" coelacanth anatomy was the reason for the choice of the name Rebellatrix for the authors of the first description . The specific epithet divaricerca is made up of the Latin verb “divarico” (= to spread apart) and the Greek “kerkos” (= tail).
features
Rebellatrix was a slender coelacanth that could reach an estimated four feet in length. The most striking feature of the genus is the forked, completely symmetrical caudal fin, the two ends of which end in tips. The tail fin stalk was flattened laterally. The segmentation of the distant sections of the caudal fin rays was reduced. The fin rays were reinforced at the upper and lower edge of the caudal fin. Overall, the caudal fin was mainly supported by thick, unsegmented fin rays. The shortest caudal fin ray was one eighth the length of the longest. The middle, tassel-shaped lobe of the caudal fin, which gave the coelacanth its name, was reduced. The anal fin lies behind the second dorsal fin. The section of the notochord that extends into the caudal fin is four times thinner than the part in the trunk.
Way of life
The slim body with a forked tail fin suggests a fast swimming fish. Rebellatrix is the only coelacanth with an active lifestyle. The fossil site found in the Rebel Matrix consists of deposits from a continental shelf , which could indicate that Rebel Matrix was an inhabitant of the open ocean.
Systematics
Within the coelacanth, Rebellatrix is classified as a sister group of the suborder Latimerioidei, which includes the extinct, freshwater inhabiting Mawsoniidae and the marine Latimeriidae , which also includes the two coelacanth species that still exist today.
literature
- Andrew J. Wendruff & Mark VH Wilson: A fork-tailed coelacanth, Rebellatrix divaricerca, gen. Et sp. nov. (Actinistia, Rebellatricidae, fam. Nov.), From the Lower Triassic of Western Canada. Journal of Vertebrate Paleontology, Volume 32, Issue 3, 2012 doi : 10.1080 / 02724634.2012.657317