Guaibasaurus, (meaning "Guaiba lizard"), was a basal dinosaur genus which lived during the Triassic period. Its fossils were found in the geopark of Paleorrota, Rio Grande do Sul, Brazil. Like Herreasaurus, this dinosaur had three full fingers and two vestigial ones on each hand. The type species, G. candelariai, was described by Jose Boneaparte and J. Ferigolo in 1999. Also like the Herrasaurus, the Guiabasaurus is a very early dinosaur and it is not known how it relates to later dinosaur species. Only a partial skeleteon record has been discovered for the guiabasaurus.

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