| A small minority of the Atrypacea have smooth shells, others being rather finely costate or having medium to coarse plications. |
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| Early genera were almost circular to elongate-oval, with smooth or finely costate shells. |
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| In pioneer studies, the genus was confused with some spire-bearing brachiopods because of its strophic outline and costate ribbing. |
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| All are radially costate, with costae varying from simple and evenly distributed to variously branched and unevenly spaced. |
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| The only other Eurasian finely and densely costate species known to me that is closely comparable is Leptochondria minima from the Lower Triassic of Russia. |
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| In a dynamic programming problem, this would be the costate variable associated with nonassociated gas reserves. |
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