The brontosaurus is an interesting creature: a curious mix of ambition, poor scientific methods and a part of the “bone wars” of the late 19th century. It could be described as a mythical beast with the body of one dinosaur and the head of another. Alternatively, it could be said to have resulted from the hasty misidentification of an incomplete skeleton. Although the name is still in popular use, the vast majority of paleontologists believe this particular dinosaur never existed as such: it was simply another specimen of an already known animal. For a long time, the most complete exhibit was in fact an Apatosaurus body with a Camarasaurus head.

The "brontosaurus" presented on a US postage stamp.

The Bone Wars

During the 1870s and 1880s, a bitter rivalry existed between two paleontologists, Othniel C. Marsh and Edward Drinker Cope, which became known as the “bone wars.” A number of incidents seem to have contributed to the enmity between the two. For example, it was alleged that Marsh had paid some of Cope’s workers to send the bones they had dug up to him instead of to their employer. On another occasion, Marsh publicly humiliated Cope when the latter mistakenly attached the skull of a fossilized marine reptile to its tail instead of its neck. It was against this background that the confusion regarding the Apatosaurus and the “Brontosaurus” arose.

For many years, the most complete fossilized brontosaurus display was actually an Apatosaurus with a Camarasaurus head.

The “Discovery” of the Brontosaurus

In their haste to claim new discoveries, both men could be careless in their methods, often basing their claims on very limited evidence and sometimes lumping together bones from different animals. In 1877, Marsh, on the basis of a few vertebrae and a pelvis, identified a new dinosaur, which he named Apatosaurus. It was a large sauropod — a four legged animal with a long neck and a long, tapering tail. Two years later, he examined another incomplete sauropod skeleton and declared it to be new dinosaur, which he named “Brontosaurus,” meaning “thunder lizard.”

In 1883, most of the remainder of this skeleton was found and Marsh was able to piece together an almost complete reconstruction. The skull, however, was missing. Ironically echoing Cope’s earlier mistake, he completed the skeleton by attaching the skull of another dinosaur, Camarasaurus. This error, though suspected for some time, was not confirmed until the 1970s. To be fair to Marsh, it was a common practice to use parts of similar dinosaurs to fill in missing pieces in a skeleton for public display.

A comparison of the Apatosaurus and “thunder lizard” skeletons by the paleontologist Elmer Riggs in 1903 concluded that they were the same dinosaur. Since the name “Apatosaurus” had been given first, it had to take precedence and “Brontosaurus” became redundant in scientific terms. Once the skeleton went on display, however, it caught the public imagination in a way that the Apatosaurus had not. It continued to appear with the no longer accurate name in books on dinosaurs at least until the 1970s and featured in numerous movies and cartoons.

The Apatosaurus

The idea of an enormous, herbivorous dinosaur that once walked the earth did not die with the brontosaurus. The Apatosaurus was an amazingly large beast and it was a herbivore. It grew up to 75 feet (23 m) in length and may have weighed more than 20 tons. An average sized human would have reached just a bit above its knee.

The main reason for Marsh’s misidentification of the skeleton is that the second finding had more vertebrae. This suggested a different dinosaur; however, it was later established that, as these dinosaurs grew, some of the vertebrae fused together. It seems that Marsh had simply found a younger example.

The dinosaur formerly known as brontosaurus was certainly real — it just had the wrong name and the wrong head. The main difference is that the head of the Apatosaurus was narrower, slightly longer in the snout and smaller than that of the heavy-jawed Camarasaur. If Marsh had used the term “brontosaurus” for his first sauropod discovery, the name would have been scientifically valid and might have been more appropriate. A computer simulation has suggested that the dinosaur may have been able to make a thunderous noise — possibly reaching 200 decibels — by cracking its tail like a whip.

The Thunder Lizard Lives On

This huge, arguably fictional, dinosaur lives on in the popular imagination and continues to be referred to as “real.” A well-known spell checker, for example, recognizes brontosaurus, but not the names of the two creatures that made up the original exhibit. All this is in spite of the fact that museums in the US have now corrected their displays.

At least one prominent paleontologist, however, believes that the skeleton of Marsh’s thunder lizard is sufficiently different from that of Apatosaurus for it to be considered a dinosaur in its own right. Another skeleton formerly regarded as a type of Apatosaurus has now been recognized as a different dinosaur and named Eobrontosaurus, meaning “dawn thunder lizard.” There is one place where a brontosaurus exhibit can still be seen, as of 2013: Othniel C. Marsh’s original reconstruction, albeit with a new skull, is on display at the Yale Peabody Museum of Natural History. As it forms a part of a historical record, it is labeled “Brontosaurus.”