- A taxonomic genus within the family Diplodocidae – certain large long-necked sauropods; formerly merged into Apatosaurus.
First named in 1879. The original species B. excelsus was reclassified as Apatosaurus excelsus in 1903, and the genus was thence regarded as a junior synonym of Apatosaurus. A study published in 2015 reinstated Brontosaurus as a separate genus (including also B. yahnahpin and B. parvus), although not all palaeontologists agree with the new grouping.
- (genus): Eukaryota - superkingdom; Animalia - kingdom; Bilateria - subkingdom; Deuterostomia - infrakingdom; Chordata - phylum; Vertebrata - subphylum; Gnathostomata - infraphylum; Tetrapoda - superclass; Reptilia - class; Eureptilia, Romeriida - clades; Diapsida - subclass; Archosauromorpha - infraclass; Archosauria - division; Ornithodira - subsection; Dinosauria - superorder; Saurischia - order; Eusaurischia - taxon; Sauropodomorpha - suborder; Sauropoda - infraorder; Eusauropoda - taxon; Neosauropoda - taxon; Diplodocoidea - superfamily; Diplodocidae - family
- (genus): †Brontosaurus excelsus (type species)