How Are Dinosaurs Named? Latin, Greek and the Rules of Giving a Fossil a Name
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Tyrannosaurus rex means tyrant lizard king, Triceratops means three-horned face, and Velociraptor means swift thief, and each was coined by a palaeontologist who had a set of bones on a table and the right, under an international code, to call them whatever he liked within the rules. The names are Greek and Latin because the system was made in the eighteenth century, they come in two parts because Linnaeus decided so, and they are permanent once published, which is why a dinosaur named after a mistaken idea keeps the name after the idea is dropped. About fifty new dinosaurs are named every year, and the rules for doing it are stricter than they look.
Two names
The system is Linnaeus's, from the tenth edition of his Systema Naturae in 1758, which the zoological code takes as the starting point: every species has a binomial, a genus name with a capital letter and a species name without, both in italics and both treated as Latin whatever their origin. Tyrannosaurus is the genus, rex the species, and the genus can hold more than one species, as Tyrannosaurus for a time held T. rex alone and Triceratops holds two. Most dinosaurs are known from a single species, and the genus name is the one people use; nobody says Triceratops horridus. The name that is used in books, dinosaur, was itself coined in 1842 by Richard Owen from the Greek for terrible lizard, for three animals then known from England, and it is not a formal rank at all.
Where the names come from
The describer can choose anything that can be Latinised, and the sources run in a few channels:
- •Anatomy: Stegosaurus, roof lizard, for its plates; Pachycephalosaurus, thick-headed lizard; Diplodocus, double beam, for a feature of its tail bones
- •Behaviour, real or supposed: Oviraptor, egg thief, wrongly; Maiasaura, good mother lizard, rightly
- •Places: Utahraptor, Argentinosaurus, Albertosaurus, and Mamenchisaurus for a ferry crossing in Sichuan
- •People: Othnielia and Marshosaurus for Othniel Marsh and Drinker for his rival Edward Drinker Cope, the feuding bone hunters of the 1870s; Dracorex hogwartsia, dragon king of Hogwarts, for a skull that turned out to be a young Pachycephalosaurus
- •Languages other than Greek and Latin: Tarchia, brainy one, from Mongolian; Bistahieversor from Navajo; Kunbarrasaurus from an Aboriginal language of Queensland, a growing practice that acknowledges whose land the bones came from
The rules
The International Code of Zoological Nomenclature governs the process, and its central rule is priority: the first name validly published for an animal is the name, and later ones are junior synonyms. Publication requires a description, a designated type specimen in a museum where others can examine it, and a diagnosis of what makes it distinct, and since 2012 an electronic publication counts if it is registered. The name must be unique across the animal kingdom, must not have been used before, and once published cannot be withdrawn by its author; an offensive or joking name is valid if it follows the form. The type specimen is the anchor, and a name applies to whatever the type turns out to be, which is why Brontosaurus, named by Marsh in 1879, was sunk into Apatosaurus in 1903 when the two were judged the same animal and revived in 2015 when a new analysis found them different, with the older name taking priority in each genus.
The famous mistakes
Priority keeps errors. Oviraptor, the egg thief, was found on a nest that was its own; Basilosaurus, king lizard, is a whale, named in 1834 by someone who took it for a reptile, and the code will not let the name be changed. Iguanodon was named for its teeth, which its describer thought like an iguana's, and its thumb spike was put on its nose for forty years. Tyrannosaurus rex, named by Henry Fairfield Osborn in 1905, narrowly escaped being called Dynamosaurus imperiosus, which Osborn named in the same paper from a different specimen and which would have had priority had it appeared first in the text; Osborn made rex the senior name the following year, and the second-most famous dinosaur name in the world exists because of a page order. The rules produce a stable system at the cost of a permanent record of what people once believed.
The naming boom
About 1,500 dinosaur genera have been named, and roughly half of them since 2000, as China, Argentina, Mongolia and Morocco have opened their rocks; a new one is described roughly every week. Around half the names given in the nineteenth century have since been sunk as duplicates or as scraps too poor to identify, and the same fate awaits some of the recent ones. The naming remains the palaeontologist's one act of creation, a word attached to an animal that will outlast every theory about it, and the rules that make it permanent are the reason a whale is called a king lizard and a devoted parent an egg thief.
From field jacket to published name
A dinosaur usually waits years between discovery and name. The bones are dug out still wrapped in rock, protected in plaster jackets, and taken to a laboratory where preparators spend months or longer removing the rock with small tools. Only then can the palaeontologist compare every bone with those of known species, looking for autapomorphies, features found in the new animal and nowhere else. One distinctive feature on a well-preserved bone can justify a new name, while a scrap with nothing unusual about it cannot, however exciting the find.
The description is then sent to a scientific journal, reviewed by other specialists and often revised before it appears. Most modern descriptions also include a phylogenetic analysis, a computer comparison of hundreds of anatomical characters across many species, which proposes where the new animal sits on the family tree. Names sometimes leak into newspapers or museum labels before this is finished. A name that appears without a proper description has no standing under the code and is called a nomen nudum, a naked name, until someone publishes it properly or it is quietly forgotten.
Reading a dinosaur name
Most dinosaur names are built from a small kit of Greek and Latin roots, so a little vocabulary lets you decode hundreds of them. Saurus means lizard, ops means face, odon or don means tooth, onyx means claw, raptor means robber or plunderer, venator means hunter, and titan is used for giants. Deinonychus is terrible claw, Carcharodontosaurus is shark-toothed lizard, borrowing the scientific name of the great white shark, and Microraptor is small robber. Words for size, such as micro, mega and gigas, sit alongside words for place, and the two are easily confused.
Giganotosaurus is a good test. It does not mean gigantic lizard but giant southern lizard, from the Greek notos, the south wind, because it was found in Argentina. The second half of a full name follows its own conventions. A species named after a person usually ends in i for a man or ae for a woman, so Giganotosaurus carolinii honours Rubén Carolini, the amateur fossil hunter who found it in 1993. When the species name is a Latin adjective, as horridus is, it is supposed to agree in grammatical gender with the genus, much as adjectives must agree with nouns in French or Spanish.
The takeaway
Dinosaurs are named under the zoological code descended from Linnaeus, with a genus and species name in Latinised form chosen by the describer from anatomy, behaviour, places, people or any language, published with a description and a type specimen in a museum; the first valid name has priority for ever, which is why Oviraptor is still an egg thief and Brontosaurus came back in 2015. About fifty are named a year, half the historic names have been sunk as duplicates, and T. rex escaped being Dynamosaurus by a page.