Dinheirosaurus

Dinheirosaurus is a genus of diplodocid sauropod dinosaur known from fossils discovered in modern-day Portugal. The sole recognized species is Dinheirosaurus lourinhanensis, first described in 1999 by José Bonaparte and Octávio Mateus. The fossils originated from the Lourinhã Formation, which is dated to the early Tithonian stage of the Late Jurassic period.

Discovery and Naming

The primary fossil specimen, cataloged as ML 414, was uncovered in 1987 and excavated until 1992. Initially, the material was assigned to Lourinhasaurus alenquerensis before Bonaparte and Mateus re-evaluated it. They recognized distinct features that warranted a new binomial name, leading to the description of Dinheirosaurus lourinhanensis. The name translates to 'Porto Dinheiro lizard from Lourinhã,' referencing a local place name and the discovery site.

Description and Physical Characteristics

Dinheirosaurus was an average-sized diplodocid, characterized by an elongated neck and tail. The most diagnostic remains are its vertebrae, with both cervical and dorsal vertebrae preserved. The genus is estimated to have reached an approximate length of 20 to 25 meters (66 to 82 feet) and weighed around 8.8 metric tons (9.7 short tons). A large footprint found in the same locality, measuring 1.05 meters in length, has led to speculation that Dinheirosaurus might have attained giant sizes.

Non-vertebral material includes partial ribs and a fragment of the pelvis. The ribs are noted for their T-shaped cross-section and lack of pneumatization. Over one hundred gastroliths, or stomach stones, were also recovered with the type specimen. While gastroliths are common in birds for digestion, analysis suggests that sauropods like Dinheirosaurus may have used them primarily for mineral absorption, as the proportion of gastroliths to body weight was significantly lower than in birds.

Classification and Paleobiology

The precise phylogenetic position of Dinheirosaurus has been subject to debate. Some studies place it as a sister species to Supersaurus vivianae, forming a basal clade within diplodocines. Other research has suggested it might be a species of Supersaurus itself, designated as S. lourinhanensis. Historically, it was classified within Diplodocidae, with anatomical differences noted compared to genera like Apatosaurus. As a diplodocid, it is probable that Dinheirosaurus possessed a whip-like tail, which may have been used for communication or defense. Its relatedness to Apatosaurus and Diplodocus also suggests it likely had a squared snout and was a ground-feeding herbivore.

Paleoecology

Dinheirosaurus inhabited the Lourinhã Formation during the Late Jurassic, an ecosystem that shared similarities with the North American Morrison Formation. This fauna included a diverse array of theropods, other sauropods, and ornithischians. The presence of Dinheirosaurus and other diplodocids in Late Jurassic Europe highlights the unique biogeography of primitive sauropods in the region, suggesting their survival potentially into the Berriasian epoch.