Tuzoia parva
| Tuzoia parva | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Cambrian | ||||||||||||
| 505 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Tuzoia parva | ||||||||||||
| ( Walcott , 1912) | ||||||||||||
Tuzoia parva is a controversial fossil Arthropodenart , probably from the genus tuzoia , or larval stage of development or another, not sure attributable kind. The only known copy is the holotype , the Charles Walcott from the Canadian Burgess Shale described has. It has not yet been clarified whether it is a juvenile form of a Tuzoia species or a species belonging to another group of bivalve arthropods (such as the Bradoriida ).
features
The holotype is inclined laterally in the rock. The outline of the right flap is apparently complete, the left one appears to be folded under itself. The width is 4.2 mm and the height 2.7 mm.
The armor appears to be divided by a straight hinge-like line, which ends in a long ridge or rostrum in front and forms the upper edge. The right valve is sub-oval in outline and tapers to a blunt front edge. The rear edge is inclined about 120 ° to the upper edge, which creates a pronounced rear indentation of the armor. At least five elongated ventral spines can be seen. The carapace seems to have an indication of a narrow rim along the ventral rim. The diameter of the reticulated cells on the armor is only about 0.1 mm.
A small extension with two narrow spines can be seen protruding from the shell. Walcott interpreted this as an antenna . Briggs sees in it a telson with furca, so he interprets as the rear end what Walcott saw as the front end. Since , with a few exceptions, only the carapace of Tuzoia has been fossilized , the interpretation is difficult.
Location
The species was found in the Burgess Shale in the Canadian Rockies . Walcott claimed to have found two individuals, but only the holotype is known.
Systematics
The species was named Hymenocaris? By Charles Walcott in 1912 . parva first described. Simonetta and Delle Cave saw it as a juvenile form of Canadaspis sp. Since the genera Hymenocaris and Canadaspis do not show any prickly edges, Briggs transferred the species to the genus Tuzoia , but with an uncertain assignment, since in his opinion it is a juvenile form of Tuzoia . It is therefore unlikely that Tuzoia parva is actually a separate species.
swell
literature
- Derek EG Briggs: Bivalved arthropods from the Middle Cambrian Burgess Shale of British Columbia . In: Palaeontology . Volume 20, No. 3 , 1977, pp. 618-620 .
- Jean Vannier, Jean-Bernard Caron, Jin-Liang Yuan, Derek EG Briggs, Desmond Collins, Yuan-Long Zhao, Mao-Yan Zhu: Tuzoia: Morphology and Lifestyle of a large bivalved Arthropod of the Cambrian Seas . In: Journal of Paleontology . Volume 81, No. 3 , 2007, p. 467 , doi : 10.1666 / pleo05070.1 .
Individual evidence
- ^ Bruce S. Lieberman: A new soft-bodied fauna: The Pioche Formation of Nevada . In: Journal of Paleontology . Volume 77, No. 4 , 2003, p. 678-679 , doi : 10.1666 / 0022-3360 (2003) 077 <0674: ANSFTP> 2.0.CO; 2 .
- ^ A b Charles Walcott : Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata . In: Smithsonian Miscellaneous Collections . Volume 57, No. 6 . Washington 1912, p. 185 ( online ).
- ↑ AM Simonetta, L. Delle Cave: The Cambrian non trilobite arthropods from the Burgess Shale of British Columbia . In: Palaeontographia Italics . Volume 69, 1975, pp. 1-37 .
Web links
- USNM PAL 57716 in the collections of the Smithsonian Institution