Fossil fragments were first noticed at the site in 2017, when the owner was digging up his garden to make way for an extension.
He contacted palaeontologists, who unearthed part of the dinosaur skeleton earlier this month and have been examining it ever since.
Sauropods have characteristically long necks and tails and are among the largest animals to have ever lived.
The fossils discovered at the Monte Agudo site in Pombal are thought to be those of a brachiosaurid who lived during the Upper Jurassic period.