Nipponoolithus is a fossil egg known from Japan, specifically the Sasayama group in Kimitaki, Tamba, Hyogo, Japan. It comes from the Albian age of the Early Cretaceous. It is a very small egg, known from only a handful of fragments from between. 36 to .53 mm thick. It probably would have weighed about 100 grams, making it one of the smallest fossil dinosaur eggs ever known. It was probably laid by a Maniraptoran of some sort based on its structure and ornamentation.
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