Tietasaura (meaning "Tieta lizard") is an extinct genus of elasmarian ornithopod dinosaur from the Early Cretaceous Marfim Formation of Brazil.

The Tietasaura holotype specimen, NHM-PV R.3424, was discovered in 1906 during a series of expeditions by London's Natural History Museum to South America, lasting from 1859 to 1906.

[4] In 2024, Bandeira et al. described Tietasaura derbyiana as a new genus and species of elasmarian ornithopod based on these fossil remains.

[3] In their phylogenetic analyses, Bandeira et al. (2024) recovered Tietasaura as an ornithopod member of the Elasmaria, as the sister taxon to Notohypsilophodon.

Their results are displayed in the cladogram below:[3] Hypsilophodon Kangnasaurus Macrogryphosaurus Anabisetia Talenkauen Morrosaurus Trinisaura Fulgurotherium Gasparinisaura Tietasaura Notohypsilophodon Rhabdodon Zalmoxes spp.