| Named By: | L. Cheng, X. H. Chen, Q. H. Shang & X. C. Wu in 2014 |
| Time Period: | Middle Triassic, 240 Ma |
| Location: | China, Yunnan Province |
| Size: | About 3 meters long |
| Diet: | Algae feeder |
| Fossil(s): | Few individuals |
| Classification: | | Chordata | Reptilia | |
Atopodentatus is an extinct genus of marine reptile, possibly basal sauropterygian, known from the early Middle Triassic (Pelsonian substage, Anisian stage) of Luoping County, Yunnan Province, southwestern China. It contains a single species, Atopodentatus unicus. It is thought to have lived between 247 and 242 million years ago, during the Middle Triassic period, about six million years after the Permian extinction. Atopodentatus was herbivorous marine reptile, usually marine reptiles are omnivores or carnivores.
A near complete skeleton along with a left lateral portion of the skull were discovered near Daaozi village, Yunnan, China. The scientific name derives from the peculiar zipper-shaped morphology of the holotype specimen's jaws and unique dentition. However, two fossil skulls discovered in 2016 indicate that the holotype skull was badly damaged, and that the living animal actually had a hammer-shaped head with shovel-like jaws.