Whatever happened to the Brontosaurus?
When I was about six, my grandfather introduced me to a book which he had been given as a boy. It had a picture of a Triceratops on the front cover, and I read it eagerly as far as the back cover more than once. It was the 1897 edition of Extinct Monsters: a popular account of some of the larger forms of ancient animal life, by the Rev. H. N. Hutchinson, and I did not mind in the least that it was, scientifically speaking, hugely out of date.
Plate IV in the book is an illustration, by the London-based Dutch artist Joseph Smit, captioned
‘A gigantic dinosaur, Brontosaurus excelsus.’
It depicts a genial beast with a slightly goofy smile, paddling in the Jurassic ocean and carelessly crushing palm trees with its enormous tail. But many a modern six-year-old will now tell you, with an air of professorial authority, that its proper name is Apatosaurus. Why would scientists abandon such an evocative name for such an unmistakable animal?
What we have here is a classic instance of taxonomic change (a problem familiar to any gardener who cares to wrestle with the Latin names of plants). Biologists study the natural world, and come to varying scientific opinions about the similarities and relationships between different species. Sometimes, as a result, the names have to change.
The history of the Brontosaurus
Brontosaurus excelsus was first described and named by the great American fossil-hunter Othniel C. Marsh in 1879. Its imposing name, meaning ‘thunder lizard’, passed into popular consciousness, and although its arrival in general currency came too late for inclusion in the original Oxford English Dictionary (OED) – the last part of the letter B was published in 1888 – it was added to the Supplementary Volume in 1933, with a quotation alluding to ‘the mighty brontosaurus’ in Harper’s Magazine from December 1905.
However, even by 1905, its status was in question. In 1877, Marsh had also described and named a fossil which he called Apatosaurus ajax. Although he considered his Brontosaurus to be a quite distinct species, Elmer S. Riggs of Chicago (the discoverer of Brachiosaurus) announced in 1903 that they were too similar to be placed in separate genera, and must be classified together. According to the Rules of Zoological Nomenclature, the older name took priority, so Brontosaurus excelsus became Apatosaurus excelsus.
However, just as generations of gardeners have carried on calling flowers of the genus Pelargonium by the name of ‘geranium’, many people carried on happily referring to members of the species Apatosaurus excelsus as ‘brontosauruses’ (or ‘brontosauri’). Even the American Museum of Natural History called their specimen ‘Brontosaurus’ when it was unveiled in 1905.
The Rev. H. N. Hutchinson’s Extinct Monsters, I was pleased to discover, is cited by the OED as containing (in its first 1892 edition) the earliest known use of the word Brontosaur. This originated simply as an anglicized form of the name, discarding the Latin suffix. Professor Richard Owen had himself introduced the term Dinosaur in 1841, almost in the same breath as his new Latin coinage Dinosauria, a name for a whole group of extinct giant reptiles. Even though the Latin names were swiftly assimilated into an English context, many writers found that using them all the time became ponderous, and Hutchinson happily alternates between Brontosaurus and Brontosaur, Ichthyosaurus and Ichthyosaur, Plesiosaurus and Plesiosaur, and so on. There is in some cases a precedent in French: for example, plésiosaure (1826) is earlier than its English equivalent. (The capital letter, compulsory in the Latin genus name, is a matter of taste or style in an English context, and tends to be dropped as a name becomes familiar.)
As palaeontology developed and more fossils were found, the terminology became more elaborate. When Owen first used the name mosasaur (1842) for a reptile of the genus Mosasaurus (1822), there was already a range of fossils regarded as mosasaurian (1849), and Owen acknowledged the existence of a whole mosasauroid (1849) family, which the French zoologist Paul Gervais christened Mosasauridae (1853) and the American geologist J. D. Dana referred to as mosasaurids (1875).
So it is that the -saur words have become more general in their application. When Tyrannosaurus was described in 1905, it was the only member of the family Tyrannosauridae, and tyrannosaur simply referred to the same animal. Since then, other tyrannosaurids such as Tarbosaurus and Alioramus have been added to the group. The term tyrannosaur remains vaguer in application, though it is usually applied to the members of the family Tyrannosauridae, and not to the earlier and smaller tyrannosauroids.
So is the Brontosaurus obsolete as well as extinct?
While some of us old-fashioned types still fondly talk of the Brontosaurus, it may even be that scientific progress will catch up with us again. Palaeontologists continue to debate whether the differences between Apatosaurus ajax and Apatosaurus excelsus justify separating them again, and those who would rather split them can revive the genus name Brontosaurus. However, since the extent of a genus is a matter of scientific opinion, not scientific observation, the matter can really only reach a consensus, not a definitive conclusion.
Image credit: Joseph Smit, from Extinct Monsters, by the Rev. H. N. Hutchinson, 1897