| Named By: | K. T. Smith & M. C. Buchy in 2008 |
| Time Period: | Late Cretaceous, 100 Ma |
| Location: | Mexico - Agua Nueva Formation |
| Size: | Uncertain, but the rear portion of the post cranial skeleton is 2 meters long, suggesting a small to medium size for this mosasaur |
| Diet: | Carnivore |
| Fossil(s): | Rear half of the post cranial skeleton |
| Classification: | | Chordata | Reptilia | Squamata | Mosasauroidea | |
Vallecillosaurus is an extinct genus of mosasauroid from the Late Cretaceous period, that lived in Mexico, in the state of Nuevo Leon.