The genus name Gallardosaurus is a tribute to Juan Gallardo, the farmer credited with the initial discovery of the remains in 1946.

Gallardosaurus is among the limited number of marine reptiles identified in the Cuban fossil record, hinting at its probable presence in Mesozoic seas beyond the waters that would eventually become Cuba, given its marine nature.

Gallardosaurus is a genus of a pliosaurid plesiosaur discovered within the Caribbean seaway, featuring the sole species Gallardosaurus iturraldei. This particular species of Gallardosaurus was unearthed within rocks from the Late Jurassic period, situated in the Jagua Formation located in western Cuba. It's thought that Gallardosaurus shares an evolutionary lineage with Peloneustes, a frequently encountered pliosaurid in Oxfordian-aged deposits.

Gallardosaurus is likely to have engaged in seasonal migrations throughout the Caribbean Seaway, primarily preying on nectonic fish inhabiting the region where it lived. Within the Jagua Vieja Member, one can also find ichthyosaurs, the marine turtle Notoemys oxfordiensis, and the plesiosauroid Vinialesaurus caroli. The water depth in this area was relatively shallow, estimated at around 10 to 12 meters (33 to 39 feet), with the sea floor being colonized by oysters and algae. Additionally, fragmentary remains of plants, pterosaurs, and dinosaurs from nearby coastal areas would have washed into this environment.