It was described by American paleontologist Othniel Charles Marsh in 1879, the type species being dubbed B. excelsus, based on a partial skeleton lacking a skull found in Como Bluff, Wyoming.

For decades, the animal was thought to have been a taxonomic synonym of its close relative Apatosaurus, but a 2015 study by Emmanuel Tschopp and colleagues found it to be distinct.

Being from the Morrison Formation, Brontosaurus coexisted with a menagerie of other taxa such as the sauropods Diplodocus, Barosaurus, and Brachiosaurus; herbivorous ornithischians Stegosaurus, Dryosaurus, and Nanosaurus; as well as the carnivorous theropods Allosaurus, Marshosaurus and Ceratosaurus.

[7] Brontosaurus excelsus' type specimen (YPM 1980) was one of the most complete sauropod skeletons known at the time, preserving many of the characteristic but fragile cervical vertebrae.

[8] A year later in 1880, another partial postcranial Brontosaurus skeleton was collected near Como Bluff by Reed,[9][10] including well-preserved limb elements.

[15] The adult skeleton specifically was very well-preserved, bearing many cervical (neck) and caudal (tail) vertebrae, and is the most complete definite specimen of the species.

The species was later transferred to Apatosaurus by several authors[16][17] In 2008, a nearly complete postcranial skeleton of an apatosaurine was collected in Utah by crews working for Brigham Young University (BYU 1252-18531) where some of the remains are currently on display.

[19] Nonetheless, before the mounting of the American Museum of Natural History specimen, Henry Fairfield Osborn chose to label the skeleton "Brontosaurus", though he was a strong opponent of Marsh and his taxa.

It was accepted as belonging to the Apatosaurus specimen by Douglass and Carnegie Museum director William J. Holland, although other scientists, most notably Osborn, rejected this identification.

[20] In 1995, the American Museum of Natural History followed suit, and unveiled their remounted skeleton (now labelled Apatosaurus excelsus) with a corrected tail and a new skull cast from A.

The specimen consisted of a partial postcranial skeleton, including a complete manus and multiple vertebrae, and was described by James Filla and Pat Redman a year later.

[26] In 2015, an extensive study of diplodocid relationships by Emanuel Tschopp, Octavio Mateus, and Roger Benson concluded that Brontosaurus was indeed a valid genus of sauropod distinct from Apatosaurus.

The scientists developed a statistical method to more objectively assess differences between fossil genera and species and concluded that Brontosaurus could be "resurrected" as a valid name.

[45][46][19] The shape of the tail was typical of diplodocids, being comparatively slender, due to the vertebral spines rapidly decreasing in height the farther they are from the hips.

Proportions of the manus bones vary within Apatosaurinae as well, with B. yahnahpin's ratio of longest metacarpal to radius length around 0.40 or greater compared to a lower value in Apatosaurus louisae.

However, an extensive study published in 2015 by a joint British-Portuguese research team concluded that Brontosaurus was a valid genus of sauropod distinct from Apatosaurus.

[28] Marsh also noted the animal's supposed lack of intellect based on the small braincase of the Felch Quarry skull and slender neural cord.

[52] Trackways of sauropods like Brontosaurus show that the average range for them was around 20–40 km (10–25 mi) per day, and they could potentially reach a top speed of 20–30 km/h (12–19 mph).

[72] Historically, sauropods like Brontosaurus were believed to have been too massive to support their weight on dry land, so theoretically, they must have lived partly submerged in water, perhaps in swamps.

[75]James Spotila et al. (1991) suggest that the large body size of Brontosaurus and other sauropods would have made them unable to maintain high metabolic rates, as they would not be able to release enough heat.

Paladino calculates its tidal volume (the amount of air moved in or out during a single breath) at 0.904 m3 (904 L) with an avian respiratory system, 0.225 m3 (225 L) if mammalian, and 0.019 m3 (19 L) if reptilian.

[77] A 1999 microscopic study of Apatosaurus and Brontosaurus bones concluded the animals grew rapidly when young and reached near-adult sizes in about 10 years.

[15] Peterson and Gilmore also theorized that sauropods never stopped growing, which supposedly helped in attaining their massive size, a concept unsupported by fossils.

[81] An article that appeared in the November 1997 issue of Discover magazine reported research into the mechanics of diplodocid tails by Nathan Myhrvold, a computer scientist from Microsoft.

The Morrison Basin, where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan and was formed when the precursors to the Front Range of the Rocky Mountains started pushing up to the west.

[95] Dinosaurs known from the Morrison include the theropods Ceratosaurus, Ornitholestes, and Allosaurus, the sauropods Apatosaurus, Brachiosaurus, Camarasaurus, and Diplodocus, and the ornithischians Camptosaurus, Dryosaurus, and Stegosaurus.

[96] Other vertebrates that shared this paleoenvironment included ray-finned fishes, frogs, salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphs, and several species of pterosaurs.

[100] The 1933 film King Kong featured a Brontosaurus chasing Carl Denham, Jack Driscoll and the terrified sailors on Skull Island.

[101] Sinclair Oil Corporation has long been a fixture of American roads (and briefly in other countries) with its green dinosaur logo and mascot, a Brontosaurus.

While Sinclair's early advertising included a number of different dinosaurs, eventually only Brontosaurus was used as the official logo, due to its popular appeal.