Journal
GFF
Volume 132, Issue 1, Pages 13-24Publisher
TAYLOR & FRANCIS LTD
DOI: 10.1080/11035891003597083
Keywords
Dalmanella; Orthida; Brachiopoda; Late Ordovician; Sweden; North America
Categories
Funding
- Swedish Museum of Natural History, Stockholm
- Natural Sciences and Engineering Research Council of Canada
Ask authors/readers for more resources
Examination of topotype material of the type species of Dalmanella, D. testudinaria, from the Hirnantian strata of Borenshult, southern Sweden, revealed several diagnostic characters that distinguish the type species from some common North American species assigned previously to the genus. The typical Dalmanella testudinaria has a consistently developed, primary medial interspace in the dorsal valve, a cardinal process with an invariably bilobed myophore, punctae of two distinctly different sizes, and a lack of aditicules. In contrast, many Late Ordovician species from North America, such as 'Dalmanella' meeki and 'Dalmanella' multisecta from the Cincinnati type area, consistently have a dorsal medial costa, with a strong tendency to develop aditicules and a trilobate cardinal process. This study confirms the previous notion of many authors that true Dalmanella testudinaria, or the genus as a whole, is either rare or entirely absent in North America. Typical Dalmanella was predominant in cool-water depositional environments (such as the Hirnantia Fauna), whereas the North American dalmanellids (e.g. Cincinnati-type 'Dalmanella', Paucicrura, and Diceromyonia) were most abundant and diverse in tropical, epicontinental sea settings. A clear definition of the true Dalmanella, therefore, has important implications for the study of Late Ordovician-Early Silurian brachiopod evolution, paleoecology, and paleobiogeography.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available