Abstract
a genus of planulate ammonoids in the order Ammonitida; only 3 inches wide at the most but very numerous; it was part of the radiation of ammonitids that followed the extinction of most ceratitid ammonoids at the end of the Triassic; occurring in the Pliensbachian, always in a stratum just above that of Amaltheus, it is a significant index fossil; global distribution, Early Jurassic, 200 to 172 Ma.
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Carlton, R.L. (2018). D. In: A Concise Dictionary of Paleontology. Springer, Cham. https://doi.org/10.1007/978-3-319-73055-4_4
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DOI: https://doi.org/10.1007/978-3-319-73055-4_4
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