Miodelphinus fossil map
Where fossils of Miodelphinus have been found, shown on the Earth as it looked about 15 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 15 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Early mammals |
|---|---|
| Lived | 20.45–15.98 million years ago (Burdigalian) |
| Periods | Neogene |
| Family | Squalodelphinidae |
| Named by | Tanaka and Nakagawa 2024 |
| Fossil records | 2 occurrences at 1 locations (PBDB) |
| Found in | Japan |
| Rock formations | Haze |
About Miodelphinus
Miodelphinus is an extinct genus of platanistoid dolphin that lived during the Miocene epoch, about 18.7–18.5 million years ago. Its fossil, which was found in 1991 at Haze Formation (Japan) and described as a new genus in 2024, consists of a portion of its skull, hyoid bones, and ribs. The preserved part of the skull is 30 cm long with 4 cm long ear bones. The periotic of Miodelphinus shows a large, posteriorly widened, ventrally opening, funnel-like articular depression between the posterior and articular processes of the periotic. Based on the morphology and phylogenic studies, Miodelphinus is classified as a member of squalodelphinids. And differ compared to living platanistoids that lived in the river; squalodelphinids are marine mammals and their closes living relatives are the two species of South Asian River Dolphins.
Text in “About” is quoted from the Wikipedia article Miodelphinus (revision 1359285102), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 23 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q130581538.
