Arctica sp.
Description
? Arctica sp.
Fig. 14.
1925 Astarte spec.; Hägg 1925: 45, pl. 3: 9.
2016 Astartiidae? sp. 1; Hryniewicz et al. 2016: table 2.
Material. — One specimen (NRM-PZ Mo 149143), shell, from the upper Paleocene of Fossildalen, Spitsbergen, Svalbard.
Measurements. —NRM-PZ Mo 149143: L, 26.9 mm; H, 22.5 mm; W, 12.5 mm.
Description. —Shell medium-sized, oval with prosogyrate, weakly anteriorly incurved umbones. Anterodorsal margin concave, with incised lunular area, anterior margin rounded, continuous with rounded ventral margin. Posterior margin rounded, passing into straight, dorsally inclined posterodorsal margin. Outer surface sculptured with many very fine growth lines (8 per 1 mm). Details of inner shell surface unknown.
Remarks. —After closer examination of the specimen illustrated by Hägg (1925), we conclude it is most likely a species of Arctica sp. based on the external shell shape, position and character of the beak, straight and dorsally inclined posterodorsal shell margin, and numerous very fine commarginal growth lines. The latter character could be related to very slow growth (Morton 2011), known from the extant long-living species Arctica islandica (Linnaeus, 1767). Arctica ovata (Meek and Hayden, 1858) from the Paleocene Cannonball Formation of South and North Dakota Cvancara 1966) and Danian (lower Paleocene) Prince Creek Formation in Alaska (Marincovich 1993), both USA, is similar to? Arctica sp. in general shell shape. However, due to the lack of data on the dentition of the Svalbard material, we are unable to compare the two species in more detail. The same applies to Arctica sp. 1 from the lower Danian Paleocene) Agatdal Formation in Nuussuaq (Petersen and Vedelsby 2000), Greenland.
Notes
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Additional details
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Biodiversity
References
- Hagg, R. 1925. A new Tertiary fauna from Spitsbergen. Bulletin of the Geological Institution of the University of Uppsala 20: 39 - 55.
- Hryniewicz, K., Bitner, M. A., Durska, E., Hagstrom, J., Hjalmarsdottir H. R., Jenkins, R. G., Little, C. T. S., Miyajima, Y., Nakrem, H. A., and Kaim, A. 2016. Paleocene methane seep and wood-fall marine environments from Spitsbergen, Svalbard. Palaeogeography, Palaeoclimatology, Palaeoecology 462: 41 - 56.
- Morton, B. 2011. The biology and functional morphology of Arctica islandica (Bivalvia: Arcticidae): A gerontophilic living fossil. Marine Biology Research 7: 540 - 553.
- Linnaeus, C. 1767. Systema naturae, Tom. I. Pars II. Editio duodecima, reformata, 533 - 1327. Laurentius Salvius, Holmiae.
- Meek, F. B. and Hayden, F. V. 1858. Descriptions of new genera of fossils, collected by Dr. F. V. Hayden, in Nebraska territory, under the direction of Lieut. G. K. Warren, US Topographical Engineer; with some remarks on the Tertiary and Cretaceous formations of the north-west, and parallelism of the latter with those of other portions of the United States and Territories. Proceedings of the Academy of Natural Sciences of Philadelphia (for 1857) 9: 117 - 148.
- Cvancara, A. M. 1966. Revision of the fauna of the Cannonball Formation (Paleocene) of North and South Dakota. Contributions from the Museum of Paleontology, The University of Michigan 20: 277 - 365.
- Marincovich, L. Jr. 1993. Danian mollusks from the Prince Creek Formation, northern Alaska, and implications for Arctic Ocean paleogeography. The Paleontological Society Memoir 35: 1 - 35.
- Petersen, G. H. and Vedelsby, A. 2000. An illustrated catalogue of the Paleocene Bivalvia from Nuusquaq, Northwest Greenland: their paleoenvironments and the paleoclimate. Steenstrupia 25: 25 - 120.