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Lethaia is a quarterly peer-reviewed scientific journal of Earth science, covering research on palaeontology and stratigraphy. Now published by Wiley-Blackwell, it was originally published by the International Commission on Stratigraphy. It is an official publication of the International Palaeontological Association and the International Commission on Stratigraphy. The journal had a 2012 impact factor of 2.488, ranking it 7th out of 48 journals in the category "Paleontology", though its IF has since declined.