| Monquirasaurus | |
|---|---|
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| Holotype specimen in Villa de Leyva, Boyaca, Colombia | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | †Sauropterygia |
| Order: | †Plesiosauria |
| Family: | †Pliosauridae |
| Genus: | †Monquirasaurus Noè & Gómez-Pérez, 2021 |
| Species: | †M. boyacensis
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| Binomial name | |
| †Monquirasaurus boyacensis (Hampe, 1992)
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| Synonyms | |
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Monquirasaurus ("Monquirá lizard") is an extinct genus of giant short-necked pliosaurs who lived during the Early Cretaceous (Aptian) in what is now Colombia. One species is known, M. boyacensis, described in 2021 from an almost complete fossil skeleton, discovered in 1977 in the town of Villa de Leyva, located in Boyacá. Published descriptions of the holotype specimen estimate that it should reach a total size approaching 8 m (26 ft) in length, making Monquirasaurus a large representative of the pliosaurids.
The taxon has long been informally identified as a species belonging to the related genus Kronosaurus, even being named Kronosaurus boyacensis in a study published in 1992. This identification was due to the fact that the holotype specimen was banned from local access, and the descriptions were published with the help of photos. It is not until 2021 that a more complete description of the skeleton is made, confirming that it belongs to a separate genus.
The site where Monquirasaurus was discovered is the Paja Formation, that was once an environment containing a vast diversity of marine reptiles, including other large related pliosaurs, such as Stenorhynchosaurus and Sachicasaurus.