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Ventral valve
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Eospirifer togatus
Phylum: Brachiopod
Genus: Eospirifer Species: Eospirifer togatus Location found: Baton River |
The genus Eospirifer has a long history, from the Ordovician, through the Silurian into the early Devonian. Globally, it reached its widest range in the Wenlock stage of the Silurian, when its shells were also at their largest and its diversity greatest; during the subsequent Ludlow stage, however, it declined in range, size and diversity, and seems to have survived into the Devonian only in Australasia. There is nevertheless some confusion over the classification of the genus, with some suggestion that New Zealand specimens from the Devonian may properly refer to the genus Myriospirifer.
The species is confined to the Baton River deposits, and even there good specimens are hard to find. The type specimens pictured here show the slightly smaller ventral valve (above) and the larger dorsal valve (right) with the protruding pedicle. Both shells are sulcate - i.e. have a marked 'furrow' running from the beak to the rim of the shell. Images to the right - all from the Baton River - show other specimens in the collection and illustrate the range of forms that might be found, depending on which shell is preserved, whether the specimen is an internal cast or an external mould, and the state of preservation. They show also the challenges faced in trying to identify fossils! Further reading: Garcia-Alcide, J.L. & Blodgett, R.R. 2001 New Lower Devonian (upper Emsian) Myriospirifer (Brachiopoda, Eospiriferinae) species from Alaska and northern Spain and the paleogeographic distribution of the genus Myriospirifer. Journal of the Czech Geological Society 46, 3-4, 145-154. Zhan, R. et al. 2012 Evolution and paleogeography of Eospirifer (Spiriferida, Brachiopoda) in Late Ordovician and Silurian. Science China Earth Science 55(9), 1427-1444. |
Dorsal valve
Other Specimens in the Collection
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