Dinosaurs and MLA Style

Scientific terminology for animals, also called “taxonomic nomenclature,” sometimes poses problems for the nonspecialist writer. A taxonomic term such as Homo sapiens is composed of two Latin words denoting the genus and species: Homo means “human” and sapiens means “thinking.” As we have explained in a previous Style Center post, MLA style follows our colleagues at the Chicago Manual of Style when writing about this kind of term (sec. 8.121). According to Chicago, these terms are italicized, and the genus (Homo) is capitalized while the species (sapiens) is lowercased.

Most animals are known colloquially by names other than their formal scientific names. Canis familiaris is usually just called a “dog,” for example. Not so with dinosaurs, however. The English language has no colloquial counterpart for scientific, taxonomic forms such as stegosaurus and triceratops.

This means that writers have to contend with the Latinate taxonomic nomenclature when they write about these prehistoric creatures. Consequently, one sees a lot of variations of the scientific names in nonscientific writing about dinosaurs. For example, it’s common to find Tyrannosaurus Rex (with the species name capitalized), tyrannosaurus (lowercasing the genus and omitting the species), or even T. rex (abbreviating the genus).

There is also some variation among the different genera and species. The formal taxonomic name of the stegosaurus is Stegosaurus ungulatus. But the commonly used form stegosaurus predominates instead of the full form, in contrast to Tyrannosaurus rex. Capitalization also varies. Some dictionaries have stegosaurus while others have Stegosaurus. These terms are generally italicized, but there are exceptions. For instance, one sometimes sees “tyrannosaur” used to refer generically to any member of the family Tyrannosauridae. Since “tyrannosaur” isn’t a formal genus name, it’s usually not italicized.

My advice for the everyday writer faced with all this variation is to choose one strategy for presenting these terms and to be consistent in a given piece of writing. If you use the formal name Tyrannosaurus rex, it makes sense to capitalize other names like Stegosaurus and Triceratops. If that’s too formal for what you’re writing, then it’s perfectly acceptable to use lowercase terms like tyrannosaurus (or tyrannosaurus rex), stegosaurus, and triceratops.

Using a dictionary while you write will help you with other potential problems in style, such as plural forms. For example, Merriam-Webster’s Collegiate Dictionary lists triceratops as the plural of triceratops, though it also gives triceratopses as an alternative (“Triceratops”). Simply using the first form listed in a dictionary can be a helpful way to narrow down the many options that exist when working with these terms. 

Works Cited

The Chicago Manual of Style. 18th ed., U of Chicago P, 2024, www.chicagomanualofstyle.org/home.html.

“Triceratops, N.” Merriam-Webster’s Collegiate Dictionary, 2025, unabridged.merriam-webster.com/collegiate/triceratops.