On the proper use of T. rex

I am not now, nor have I ever been a grammar-nazi (though I do like an Oxford comma). I try to keep my sentences in order but I make mistakes, and I'm not one to call a person out on their creative usage of the English language (or even creative spellings for that matter). However, the constant misspelling/misuse of Tyrannosaurus rex and T. rex is driving me nuts.

Regardless of author or content nearly every article in nearly every media (barring peer reviewed scientific papers) will use some incorrect method to refer to the "tyrant lizard king". TRex, T-Rex, t Rex, rex, Tyrannosaurus Rex, Tea Rex (though this one is a pretty decent kids book so I'll let it slide); all of these are wrong and need to stop. Tyrannosaurus rex and by extension T. rex is the scientific name of an organism and therefore must conform to the rules regarding scientific names.

Illustration for article titled On the proper use of iT. rex/i

Quick background

In 1753 Carl Linnaeus published Species Plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas(English: The Species of Plants… etc.) which essentially laid down the rules for binomial nomenclature or how we give scientific names to most organisms (bacteria play by their own rules).

Illustration for article titled On the proper use of iT. rex/i

Prior to Linnaeus, organisms were named using polynomial nomenclature; instead of a nice simple name they were given multipart Latin descriptions which were less than ideal. For example: catnip (Nepeta cataria) was given the name Nepeta floribus interrupte spicatus pedunculatis or Nepeta with flowers in an interrupted pedunculated spike. Granted this is a great description of catnip but becomes somewhat tedious if you ever want to actually talk about catnip.


There are whole books (specifically the International Code of Botanical Nomenclature and the International Code of Zoological Nomenclature) which lay out the rules for scientific names but for the purposes of this post there are five things to know when writing a species name:

  1. A species' name is comprised of two parts: a genus and a specific epitaph
  2. The genus is always capitalized
  3. The specific epitaph is never capitalized and must be preceded by the genus
  4. The name must be italicized (or underlined) to differentiate it from other text
  5. The species' name can be shortened to the first letter of the genus followed by a period and then the specific epitaph only after it has been written in full.

To demonstrate; our species' name is Homo sapiens. Homo is our genus and sapiens is our specific epitaph; and now that our full name has appeared in this post we can shorten it to H. sapiens.

In the case of the dinosaur mentioned in the opening paragraph its correct scientific name is Tyrannosaurus rex. Its genus is Tyrannosaurus (which it may or may not share with Tyrannosaurus bataar also called Tarbosaurus bataar) and its specific epitaph is rex; and since its full name has appeared in this post we can shorten it to T. rex.

Illustration for article titled On the proper use of iT. rex/i

The Why

You might be asking yourself "why should I care?". The short answer is simple: if there is a right way to do something and a wrong way to do something and they took the same amount of effort, why would you not just do it the right way.


The longer answer is that there are only 26 letters in the Latin alphabet (well 22 but the ICZN makes a special case for j, k, w, and y). Though only closely related species can share a Genus* a specific epitaph can be reused over and over again for multiple Genera. This causes problems when two or more species share a specific epitaph and have Genera that start with the same letter. In the case of a popular combination like T. rex it gets ridiculous as researchers and others try to borrow some of the limelight from Tyrannosaurus rex.

Other things you could call T. rex :

  • T. rex: Tachyoryctes rex – king mole rat
  • T. rex: Tetragonodon rex – seed shrimp
  • T. rex: Thoristella rex – sea snail
  • T. rex: Trialeurodes rex – whitefly
  • T. rex: Tyrannasorus rex - fossil beetle – side note: the beetle people need to be stopped
  • T. rex: Tyrannobdella rex – leech
  • T. rex: Tyrannoberingius rex – fossil gastropod
  • T. rex: Tyrannomyrmex rex – ant
  • T. Rex: Tyrannosaurus Rex – 1970's band
  • T-Rex: restaurant
  • T-Rex: cyclecar by Campagna
  • T-Rex: truck by Bremach
  • T-Rex: truck by DodgeT-Rex: Colorado Department of Transportation project

Granted from context it is usually pretty easy to figure out what T. rex a person is talking about but phrases like "this T.rex fossil" or "the deadly T. rex" could refer to several if not all of the above.


(*highly unrelated organisms that fall under the different Codes can also share a Genus such as Pieris which can be a type of plant or a type of butterfly.)


An argument can be made that T-Rex, t.rex, TRex, etc. could be considered a common name for Tyrannosaurus rex. There are numerous issues with common names, but that is a topic for a whole different post so I won't get into them here. I am willing, however, to accept a common name for Tyrannosaurus rex under one condition: a correct spelling must be decided upon. Can you imagine how frustrating it would be if every time somebody wanted to write about magpies they spelt the name however they wanted. How long would you put up with megpie, magpi, magπ, or even mag(τ/2)?


I propose that for the dinosaur Tyrannosaurus rex we adopt a common name of t-rex. This form of the name is already in use by some, it is easy to spell, but there are still a few rules to follow; this is the English language after all. Common names are considered common nouns and therefor conform to the rules of capitalization and grammar used by all common nouns. Capitalization only occurs at the beginning of sentences, if the name contains a proper noun (Richardson's ground squirrel), or if the organism is a plant cultivar (Red Delicious). T-rex being neither a proper noun, nor a plant cultivar, is thus only capitalized at the beginning of a sentence and is otherwise written as t-rex.

Illustration for article titled On the proper use of iT. rex/i

There I've said my peace. Thank you for indulging me in my little rant. Hopefully now that you know a little about scientific names the misuse of T. rex will bother you as much as the misuse of too/to, their/they're/there, and your/you're and I won't be alone when I yell at my screen (not that I'd ever do that…)

Images stolen from:

Share This Story

Get our newsletter