Hidden Mosasaur Bones Uncovered in Decades-Old Japanese Fossil Suggest New Species
Researchers reexamined a 30-year-old fossil from Osaka and identified four previously missed mosasaur bones, including the first confirmed premaxilla in Japan.
A collaborative group of paleontologists returned to unprepared rock gathered between 1990 and 1992 in Sobura, Kaizuka City, Osaka Prefecture, and uncovered four hidden mosasaur bones. The most notable is a premaxilla, the first confirmed example of this upper-jaw bone in a Japanese mosasaur fossil. Examination of the basisphenoid revealed short, horn-like projections and the absence of a ventral median groove, features that differ from all previously described mosasaurs.
These anatomical oddities suggest the specimen could belong to an as-yet-undescribed species. The discovery highlights the value of re-studying museum collections and may refine understanding of Cretaceous marine ecosystems in the northwestern Pacific. Results were shared at the 177th Annual Meeting of the Palaeontological Society of Japan held at Osaka Metropolitan University.
Why it matters
The find could expand knowledge of ancient marine reptiles and reveal a previously unknown species.
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