| Named By: | J. F. Bonaparte & O. Mateus in 1999 |
| Time Period: | Late Jurassic, early Tithonian |
| Location: | Portugal - Camadas de Alcobaca Formation |
| Size: | Uncertain, but roughly estimated to be about 25 meters long |
| Diet: | Herbivore |
| Fossil(s): | Partial post cranial remains including ribs, vertebrae and limbs |
| Classification: | | Chordata | Reptilia | Dinosauria | Sauropodomorpha | Diplodocidae | Diplodocinae | |
Dinheirosaurus is a genus of diplodocid sauropod dinosaur that is known from fossils uncovered in modern-day Portugal. It may represent a species of Supersaurus. The only species is Dinheirosaurus lourinhanensis, first described by Jose Bonaparte and Octavio Mateus in 1999 for vertebrae and some other material from the Lourinha Formation. Although the precise age of the formation is not known, it can be dated around the early Tithonian of the Late Jurassic.
The known material includes two cervical vertebrae, nine dorsal vertebrae, a few ribs, a fragment of a pubis, and many gastroliths. Of the material, only the vertebrae are diagnostic, with the ribs and pubis being too fragmentary or general to distinguish Dinheirosaurus. This material was first described as in the genus Lourinhasaurus, but differences were noticed and in 1999 Bonaparte and Mateus redescribed the material under the new binomial Dinheirosaurus lourinhanensis. Another specimen, ML 418, thought to be Dinheirosaurus, is now known to be from another Portuguese diplodocid. This means that Dinheirosaurus lived alongside many theropods, sauropods, thyreophorans and ornithopods, as well as at least one other diplodocid.
Dinheirosaurus is a diplodocid, a relative of Apatosaurus, Diplodocus, Barosaurus, Supersaurus, and Tornieria. Among those, the closest relative to Dinheirosaurus is Supersaurus, and together they form a clade of primitive diplodocids. While they were once considered to be diplodocines they are likely more basal than Apatosaurus.