Uncompressed specimens of Monograptus turriculatus (Barrande, 1850) from Cornwallis Island, Arctic Canada

Isolated specimens of Monograptus turriculatus (Barrande, 1850) have been recovered from calcite concretions of the turriculatus Zone (late Llandovery) from the Cape Phillips Formation, Canadian Arctic Islands. The sicula shows ventral as well as dextral lateral curvature, and the thecae show a pron...

Full description

Bibliographic Details
Published in:Canadian Journal of Earth Sciences
Main Authors: Melchin, M. J., Lenz, A. C.
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 1986
Subjects:
General Earth and Planetary Sciences
Arctic
Canada
Cornwallis
Cape Phillips
Cornwallis Island
Online Access:http://dx.doi.org/10.1139/e86-057
http://www.nrcresearchpress.com/doi/pdf/10.1139/e86-057
Description
Summary:Isolated specimens of Monograptus turriculatus (Barrande, 1850) have been recovered from calcite concretions of the turriculatus Zone (late Llandovery) from the Cape Phillips Formation, Canadian Arctic Islands. The sicula shows ventral as well as dextral lateral curvature, and the thecae show a pronounced lateral asymmetry. This asymmetry is manifest as a tear-shaped aperture, a long, laterally directed spine on the outer apertural margin, and a shorter, ventrally directed spine on the inner apertural margin. The latter spine is totally absent on the proximal thecae.Monograptus sedgwickii (Portlock, 1853) is suggested as a possible ancestor to M. turriculatus.

Similar Items