Aaveqaspis inesoni
| Aaveqaspis inesoni | ||||||||
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Aaveqaspis inesoni |
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| Temporal occurrence | ||||||||
| Lower Cambrian | ||||||||
| 521 to 514 million years | ||||||||
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| Systematics | ||||||||
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| Scientific name of the genus | ||||||||
| Aaveqaspis | ||||||||
| Peel & Stein , 2009 | ||||||||
| Scientific name of the species | ||||||||
| Aaveqaspis inesoni | ||||||||
| Peel & Stein , 2009 | ||||||||
Aaveqaspis inesoni is the only species from the monotypical genus Aaveqaspis with an uncertain position within the arthropod . What is striking about this species are the extraordinarily large marginal spines of the tail shield.
features
The body of Aaveqaspis inesoni is narrowly oval and about 26 mm long. One axis is only weakly indicated in the relief, axial furrows are completely absent. On the head shield , each tergite and the tail shield there are small nodes in the middle of the axis, which become larger and larger as they go backwards.
The head shield is semicircular with small cheek spines and has no dorsal eyes. The rear part of the axis is slightly above the 1st tergite. The thorax is parallel and consists of 5 free, overlapping, strongly curved tergites, each about 1.6 mm long in the dorsal view, which end in spines at the sides. The tail shield consists of 2 pairs of spines, whereby the segmental marginal spines, which make up about 40% of the body length, strongly dominate. The front part of the tail shield is convex and ends laterally in the marginal spines.
etymology
The generic name is made up of the Greenlandic word Aaveq for walrus and the Greek word aspis for shield. This is supposed to allude to the similarity of the marginal spines of the arthropod with the tusks of the seal species. The specific epithet inesoni was chosen in honor of Jon R. Ineson .
Location
A total of 3 specimens of the species were found in the lower Cambrian fossil deposit Sirius-Passet on the Pearyland peninsula in Greenland . The completely preserved holotype (MGUH 29,130) and the two paratypes (MGUH 29,131 and MGUH 29,132), with slight deformations on the left side, are now in the Geological Museum in Copenhagen , part of the Danish National Museum .
Systematics
The systematic position within the arthropods has not yet been clarified. Aaveqaspis inesoni is similar in shape to Buenaspis forteyi Budd, 1999, which, however, has 6 instead of 5 tergites and has no terminal spines. Acanthomeridion serratum Hou, Chen & Lu, 1989 also has spines on the thorax and tail shield, but these are flattened and there is a tergite without spines. A. inesoni also has similarities with Sinoburius lunaris Hou, Ramsköld & Bergström, 1991 , but S. lunaris has bulges for lateral eyes, of which there are no signs of A. inesoni .
literature
- JS Peel, M. Stein: A new arthropod from the lower Cambrian Sirius Passet Fossil Deposit of North Greenland . Bulletin of Geosciences 84 (4), 2009, pp. 625-630. PDF