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Full-Text Articles in Physical Sciences and Mathematics
The Orientation Of Strophomenid Brachiopods On Soft Substrates, Roy Plotnick, Benjamin Dattilo, Daniel Piquard, Jennifer Bauer, Joshua Corrie
The Orientation Of Strophomenid Brachiopods On Soft Substrates, Roy Plotnick, Benjamin Dattilo, Daniel Piquard, Jennifer Bauer, Joshua Corrie
Benjamin F. Dattilo
Strophomenid brachiopods have long been interpreted as ‘‘snowshoe’’ strategists, with their flattened concavoconvex valves providing resistance to foundering in very soft sediments. There has been a sharp difference of opinion in whether the shells were oriented with their convex or their concave surface in contact with the sediment. This study, along with independent evidence from sedimentology, ichnology, and morphology, indicates that the strophomenids lived with their shells concave down (convex up). Experiments indicate the force required to push shells into soft cohesive muds is much greater for the convex up than for the convex down orientation. Forces also increase with …
Martellia And Associated Middle Ordovician Brachiopods From The Katkoyeh Formation, East-Central Iran, Ian G. Percival, Anthony J. Wright, Robert S. Nicoll, Mir Alireza Hamedi
Martellia And Associated Middle Ordovician Brachiopods From The Katkoyeh Formation, East-Central Iran, Ian G. Percival, Anthony J. Wright, Robert S. Nicoll, Mir Alireza Hamedi
Anthony Wright
The palaeontology and stratigraphy of the Ordovician if Iran has been the subject of considerable research over the past 15 years, revealing biogeographically significant faunas whose affinities are shared both with peri-Gondwanian terranes and continental blocks. Documentation of the composition and ages of these faunas, many of which are still poorly known, is critical to constraining palaeogeographic reconstructions of the time.