Cenomanian micromorphic ammonites from the Western Interior of the USA
Calcareous concretions from middle and upper Cenomanian (Cretaceous) shale sequences in Montana and Wyoming yield, on rare occasions, abundant minute ammonites. Some are juveniles of large species, and give valuable evidence on early ontogeny and evolutionary affinities of these taxa. They provide e...
| Main Authors: | , |
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| 格式: | Journal article |
| 語言: | English |
| 出版: |
1990
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