Protospongia
| Protospongia Temporal range: Middle Cambrian - Early Devonian[1]
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Porifera |
| Class: | Hexactinellida |
| Order: | †Reticulosa |
| Genus: | †Protospongia Salter, 1864 |
| Species | |
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Protospongia [10] is a genus of Porifera described originally from the Middle Cambrian Menevia Formation of Porth-y-rhaw, St David’s, Pembrokeshire, SW Wales. Protospongia fenestrata Salter (1864) is the type species and, although based on only small fragments of the sponge skeleton, the arrangement of at least 3 orders of cross-shaped spicules (arranged in quadrules) is clearly evident (see Rushton & Phillips 1973, text fig. 2 for graphic).[11] Six orders of spicule size were identified in the largest known example of Protospongia - a specimen of P. hicksi - from Clare Island, Co. Mayo, Republic of Ireland (Rushton & Phillips, op. cit.).
Remarks
[edit]Protospongia hicksi is probably the only member of this genus of hexactinellid sponge to occur within the Burgess Shale and is rare in the Walcott Quarry where it represents about 0.24% of the community within the Greater Phyllopod bed (Caron and Jackson, 2008).[12].
"Protospongia" rhenana Schlüter, 1892[13] from the Lower Devonian (Emsian) Hunsrück Slate of Germany, had previously been included in the genus due to the architecture of its spicules resembling that of P. hicksi. Mehl (1996), however, has since transferred Schlüter's species to the genus Cyathophycus Walcott, 1879.[14][15]
Burgess Shale fossils of P. hicksi consist entirely of fragments and isolated, cruciform spicules, so the living animal's average to maximum size and growth habitus cannot be determined. If those "Protospongia" fossils outside of the Burgess Shale are of or closely related to P. hicksi, then the growth habitus of various species would have been globular, such as P. tetranema, to cup-shaped, like Cyathophycus rhenana.
The generic homonym Protospongia Kent, 1880,[16] is a nom. illeg. because taxonomically the type species, Protospongia haeckelii Kent, is now regarded as belonging to Proterospongia Kent, 1881[17] Proterospongia is a genus of single-celled aquatic organisms which form colonies. It belongs to the choanoflagellate class and, interestingly, Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals.
References
[edit]- ^ Botting, J. (2007). "'Cambrian' demosponges in the Ordovician of Morocco: Insights into the early evolutionary history of sponges". Geobios. 40 (6): 737–748. Bibcode:2007Geobi..40..737B. doi:10.1016/j.geobios.2007.02.006.
- ^ Rigby, J. K.; Gutiérrez-Marco, J. C.; Robardet, M. and Piçarra, J. M. 1997. First Articulated Silurian Sponges from the Iberian Peninsula (Spain and Portugal). Journal of Paleontology, Vol. 71, No. 4 (Jul., 1997), pp. 554-563.
- ^ Rigby, J. K.; Nelson, J. L. and Norford, B. S., 1998. Silurian hexactinellid sponges from northern British Columbia, Canada. Journal of Paleontology 72(2):202-220
- ^ Rigby, J. K. and Harris, D. R. 1979. A new Silurian sponge fauna from northern British Columbia, Canada. Journal of Paleontology 53(4):968-980
- ^ Xiao, S.; Hu, J.; Yuan, X.; Parsley, R. L. and Cao, R. 2005. Articulated sponges from the Lower Cambrian Hetang Formation in southern Anhui, South China: their age and implications for the early evolution of sponges. Palaeogeography, Palaeoclimatology, Palaeoecology 220:89-117
- ^ Hinde, G. J. 1888. A monograph of the British fossil sponges. Part 2, 93-188
- ^ Mehl, D.; Rigby, J. K. and Holmes, S. R. 1993. Hexactinellid sponges from the Silurian-Devonian Roberts Mountains Formation in Nevada and hypotheses of hexactine-stauractine origin. Geology Studies Brigham Young University 39:101-124
- ^ Dawson, J. W. 1889. Preliminary note on new species of sponges from the Quebec Group at Little Métis. Canadian Record of Science, v. 3, p. 49-50.
- ^ Clark, T. H. 1982. Protospongia tetranema and other Cambrian sponges attributable to Dawson, not Dawson and Hinde. Journal of Paleontology, 56 (1, Part 1): 131.
- ^ Salter J. W. 1864. On some New Fossils from the Lingula-flags of Wales. Quarterly journal of the Geological Society. Vol. 20, pp. 233–241.
- ^ Rushton A. W. A. & Phillips W. E. A. 1973. A Protospongia from the Dalradian of Clare Island, Co. Mayo, Ireland. Palaeontology, vol. 16 (5): p.233 pl. 23 fig. 3. https://www.palass.org/sites/default/files/media/publications/palaeontology/volume_16/vol16_part2_pp231-237.pdf
- ^ Caron, Jean-Bernard; Jackson, Donald A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS. 21 (5): 451–65. Bibcode:2006Palai..21..451C. doi:10.2110/palo.2003.P05-070R. JSTOR 20173022. S2CID 53646959.
- ^ Schlüter, C. A. J. 1892. Protospongia rhenana. Zeitschrift der Deutschen Geologischen Gesellschaft. Band 44, Heft 4, p. 615 – 618. [Journal of the German Geological Society Volume 44 Issue 4, pp. 615 – 618.]
- ^ Mehl, D. 1996: Phylogenie und Evolutionsökologie der Hexactinellida (Porifera) im Palaeozoikum. Geologisch-Paläontologische Mitteilungen Innsbruck 4, 1–55.
- ^ Walcott, C.D. 1879. Fossils of the Utica Slate. Transactions of the Albany Institute 10, 18–19.
- ^ Kent, W. S. 1880. A manual of the Infusoria: including a description of all known flagellate, ciliate and tentaculiferous Protozoa, British and foreign, and an account of the organisation and affinities of the sponges. Vol. 1(2) pp. 144-288, 2 figures, plates 9-16. London: David Bogue.
- ^ Kent, W. S. 1881. A manual of the Infusoria: including a description of all known flagellate, ciliate and tentaculiferous Protozoa, British and foreign, and an account of the organisation and affinities of the sponges. Vol. 2(5) pp. 576-914, 11 figures, plates 33-40. London: D. Bogue.
External links
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