Bajadasaurus

Bajadasaurus; Temporal range: Early Cretaceous (Late Berriasian-Valanginian), ; ~
	Skeletal elements
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Superfamily:	†Diplodocoidea
Family:	†Dicraeosauridae
Genus:	†Bajadasaurus; Gallina et al., 2019
Species:	†B. pronuspinax
Binomial name
	†Bajadasaurus pronuspinax; Gallina et al., 2019

Bajadasaurus is a genus of sauropod dinosaur from the Early Cretaceous epoch (late Berriasian to Valanginian stages, between 145 and 132.9 million years ago) of northern Patagonia, Argentina. It was first described in 2019 based on a single specimen found in 2010 that includes a largely complete skull and parts of the neck. The only species is Bajadasaurus pronuspinax. The genus is classified as a member of the Dicraeosauridae, a group of relatively small and short-necked sauropods.

Bajadasaurus sported bifurcated (two-pronged), extremely elongated neural spines extending from the neck. Similarly elongated spines are known from the closely related and more completely known Amargasaurus. Several possible functions have been proposed for these spines in Amargasaurus; the 2019 description of Bajadasaurus suggested they could have served as a passive defense against predators in both genera. The skull was slender and equipped with around 48 teeth that were pencil-shaped and restricted to the front of the jaws. The eye openings of Bajadasaurus were exposed in top view, possibly allowing the animal to look forwards while feeding. Bajadasaurus was discovered in sedimentary rocks of the Bajada Colorada Formation, which were deposited by braided rivers. It shared its environment with other dinosaurs including the sauropods Leinkupal and Ninjatitan and different theropods.