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Brontosaurus Vs Diplodocus: What's the Difference?

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Dinosaurs dominated the fledgling ecosystems of Earth eons ago, and among their largest specimens were the sauropods: a subgroup whose members featured great, trunk-like necks, long tails, and – perhaps mercifully – a taste for leaves and plant parts rather than the flesh of other creatures. Two sauropods of note were Brontosaurus and Diplodocus.

How is Brontosaurus different from Diplodocus?

The main difference between a Brontosaurus and a Diplodocus is apparent from their physiology: while they share the same general sauropods features, Diplodocus has a longer, leaner and more streamlined body compared to Brontosaurus. Conversely, Brontosaurus was bulkier and heavier by a considerable degree.

Read on to discover what else separates the two long-necked titans!

What is a Brontosaurus?

Drawing of Brontosaurus

The Brontosaurus, alongside its cousin Brachiosaurus, is an excellent example of all defining sauropod features: its neck was long and thin, resembling an elephant’s trunk, although its head was proportionally quite small; it had a thick, bulky torso; the tail was approximately as long as its neck and flexible like a whip; and it had short but robust legs.

Brontosauruses wandered North America during the Late Jurassic period. They feasted exclusively on plant material, which was abundant. It is believed that their long necks assisted them in reaching food separated by marshes and wetlands. 

In addition to their herbivorous diet, Brontosauruses are assumed to have been docile and solitary animals, although they likely employed their long tails as whips to drive away potential predators.

What is a Diplodocus?

A representation of a Diplodocus

Diplodocus, another typical specimen of a classic sauropod, has a nearly similar morphology to Brontosaurus – with similarly long necks and tails, and sturdy legs. Additionally, they shared the same world as Brontosauruses, as both sauropods lived during the Late Jurassic period in the lands that would become North America.

In contrast to their cousins, however, the body of a Diplodocus was longer by a few meters. Its form was sleeker and leaner, although the exact purpose for this variation in morphology remains unclear. 

Diplodocus also lived off of plants, particularly leaves and softer flora, and ate its meals with its multiple rows of comb-like teeth.

Differences between Brontosaurus and Diplodocus

Physical Measurements

By virtue of being members of the sauropod clade, both dinosaurs shared the same body plan: titanic bodies that were composed of meters-long necks and tails, and heads and limbs that were proportionally smaller, and relatively bulky bodies.

The average Brontosaurus specimen, belonging to the B. excelsus species, was 22 m long from head to tail and weighed around 15 tons (about 13600 kg), placing it among the largest dinosaurs in current historical records.

As evidenced by its largest species, D. carnegii, which measured around 24-26 m in length and 12-15 metric tons (12000-13600 kg) in weight, the Diplodocus genus was longer but lighter than its Brontosaurus counterpart.


Brontosaurus and Diplodocus lived together in the Late Jurassic period – in fact, they both existed exactly during the late Oxfordian and Kimmeridgian stages of the period, and the early parts of the Tithonian stage. Each of these stages lasted for millions of years.


As with other sauropods, both dinosaurs had bifurcated (paired) spines to support great and wide necks. 

Despite being the longer dinosaur, Diplodocus had roughly 80 caudal vertebrae on average in its tail, while Brontosaurus specimens possessed at least 82 such bones. These tail vertebrae featured chevron-shaped bones or double beams that supported the Diplodocus’ spine.

The cervical vertebrae or neck bones of Brontosaurus were also stouter and more compact. Additionally, their rib bones were far longer than other sauropods, and resulted in deeper chests.

Social Behavior

Brontosaurus is theorized to have lived largely in solitude, traveling only loosely in herds. This isolating behavior has not been discussed in Diplodocus specimens, and they are believed to have traveled in herds 30-100 members large.

Feeding Habits

Both dinosaurs were strictly herbivorous, like all other sauropods. Instead of chewing their food, Diplodocus and Brontosaurus would take small stones and debris (gastroliths) into their mouths to help them grind food.

Habitat and Range

Evidence of diplodocid dinosaurs – which included both Brontosaurus and Diplodocus – was most commonly discovered in North America, although the Diplodocinae subfamily, in which Diplodocus is a member, is believed to have found its way into Africa during the Late Jurassic period as well. 

The remains of both dinosaurs are found in the Morrison Formation of sediments, which contain the remains of life in the ancient Morrison Basin ranging from current-day New Mexico to Canada from 156 to 146 million years ago.


Brontosaurus originates from the Greek βροντή (brontē), "thunder;" and σαῦρος sauros, lizard: taken together, the translation of its name is “thunder lizard.”

The Diplodocus genus’ name is also of Greek origin; from διπλός (diplos), "double;" and δοκός (dokos), "beam:" the term “double beam’ refers to the characteristic chevron bones on the inferior region of its tail, which were believed to be unique to the genus at the time.


Diplodocidae is a family that contains both dinosaurs in this comparison.

Diplodocus itself is classified as a member of the Diplodocinae subfamily, alongside Barosaurus. The two true species of this genus are D. carnegii and D. hallorum. Its closest-related species in this subfamily include:

  • Barosaurus lentus
  • Kaatedocus siberi
  • Supersaurus vivianae
  • Supersaurus lourinhanensis
  • Leinkupal laticauda
  • Galeamopus hayi
  • Torniera Africana

The Brontosaurus genus is much smaller, with only three species:

  • Brontosaurus excelsus
  • Brontosaurus yahnahpin
  • Brontosaurus parvus

B. excelsus was the first to be discovered in 1879. A dispute over whether Brontosaurus and Apatosaurus referred to the same dinosaur has been ongoing for decades; recent paleontological discussion has concluded that the two were different dinosaurs.

Comparison Chart: Brontosaurus vs Diplodocus

Physical MeasurementsHeavier and wider; 22 m long, weighing 15 tons (13.6k kg)Longer and leaner; 24-26 m long, weighing 12-15 tons (12k-13.6k kg) 
PeriodLate JurassicLate Jurassic
Vertebrae~82 tail bones, stouter neck bones, longer ribs~80 tail bones with “double-beamed” chevrons 
Social BehaviorSolitaryLarge herds
Feeding HabitsHerbivorousHerbivorous
Habitat and RangeNorth AmericaNorth America, possibly Africa
NamingGreek: “Thunder lizard” (brontē sauros)Neo-Latinized Greek: “Double-beamed” (diplos dokos)

How are Brontosaurus and Diplodocus similar? 

Brontosaurus and Diplodocus share many features in common as sauropods: their body plan was hulking and heavy, and they had distinctively long necks and tails. They kept their necks largely upright, and are believed to have used their tails to support their large vertebrae, as well as whip predators away.

Both dinosaurs enjoyed a herbivorous diet, subsisting on the plants of the Late Jurassic Period. Fossils and traces from dinosaurs of both genera have been found almost exclusively in North America as part of the Morrison Basin’s formation of sediments.

While past theories believed that they spent much of their lives in aquatic environments, with the use of their long necks to keep their heads above water, it has since been established that Brontosaurus and Diplodocus were fully terrestrial animals. 


Who would win in a fight between a Brontosaurus and a Diplodocus?

Both sauropods appear closely matched due to their physical measurements, behavior and adaptations being quite similar. 

Sauropods had claws, but their primary weapons were likely their large tails. In terms of power, the slightly bulkier build of the Brontosaurus might provide more stopping power, but Diplodocus’ longer tails and leaner frame give it the advantage of reach and speed.

If a Diplodocus could keep out of its enemy’s tail while hitting them with its own, it might win. However, due to their lumbering size and slow nature, a Diplodocus might not be able to outmaneuver a Brontosaurus, and the larger dinosaur could pummel its opponent to submission eventually.

Is Brontosaurus the same as Apatosaurus?

Any resource stating that Brontosaurus is the same dinosaur as Apatosaurus is outdated.

A comprehensive study published in 2015 concluded that Brontosaurus was entirely distinct from its fellow sauropod, Apatosaurus, after observing the anatomies of 81 specimens and comparing 477 traits in their physiology and morphology. 

The study explained that Apatosaurus was a bulkier, larger and sturdier dinosaur compared to Brontosaurus. The former’s neck was also much thicker and lower-set.


Brontosaurus and Diplodocus are genera of sauropods with subtle distinctions. 

The key differences between these dinosaurs are found in aspects such as size and build: Brontosauruses are bulkier, stouter, and heavier, while Diplodocus specimens are somewhat longer with a leaner frame.

While both lived in North America in the Late Jurassic, ate only plants, and traveled in herds, Brontosaurus is theorized to have lived a more solitary lifestyle. Some evidence suggests that Diplodocus also reached Africa.

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About the Author: Nicolas Seignette

Nicolas Seignette, who holds a scientific baccalaureate, began his studies in mathematics and computer science applied to human and social sciences (MIASHS). He then continued his university studies with a DEUST WMI (Webmaster and Internet professions) at the University of Limoges before finishing his course with a professional license specialized in the IT professions. On 10Differences, he is in charge of the research and the writing of the articles concerning technology, sciences and mathematics.
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