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The AAPG/Datapages Combined Publications Database

CSPG Special Publications

Abstract


Intl. Symposium of the Devonian system: Papers, Volume II, 1967
Pages 601-616
Biostratigraphy

Ambocoeliid Brachiopods from the Middle Devonian rocks of northern Canada

W. G. E. Caldwell

Abstract

Ambocoeliid brachiopods initially were recorded from the Devonian rocks of northern Canada by F. B. Meek a century ago. They are known now to occur most commonly in Middle Devonian (Givetian) rocks and to include a species referred tentatively to Ambocoelia Hall, 1860, a species of Echinocoelia Cooper and Williams, 1935, and several species of Emanuella Grabau, 1925.

The single species of (?) Ambocoelia and Echinocoelia are extremely rare and confined to the upper portion of the preserved Middle Devonian sequence in the Mackenzie River basin. In contrast, the five species of Emanuella described from the basin are common, and three of them occur throughout most of the fossiliferous portion of the preserved sequence. Two of Meek’s century-old species, Spirifer (Martinia) meristoides and S. (M.) sublineatus, can be referred to Emanuella, although both differ from the type species of this genus in certain features of the cardinalia. The holotype of Meek’s S. (M.) richardsoni is incipiently costate and carries dental plates, and the species probably is not an ambocoeliid.

Stratigraphical distribution supports correlation of the upper Hume, Hare Indian, and lower Ramparts Formations in the lower Mackenzie valley with the upper Chinchaga and Pine Point Formations at Great Slave Lake and endorses a Middle Devonian age for the Slave Point Formation in the subsurface of northwestern Alberta.

Ambocoeliid brachiopods in the Mackenzie River region preferred an argillaceous, calcareous, or mixed mud-grade substrate. Most species retained a functional pedicle throughout life but, with loss of this holdfast, Emanuella meristoides became sedentary and at least some specimens adopted a recumbent position upon the sea bed.


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