I was reading a TOEFL textbook and came across this sentence:

[I]t is unlikely that Brachiosaurus could have lifted its neck to reach tree leaves.

I know when it comes to referring a kind of animals, we usually use the plural form or "the" before the word in its singular form to refer to the whole kind such as:

"The cat is my favorite animal"


"Cats are my favorite animals".

It would be grammatically wrong to write

"Cat is my favorite animal."

So my question is why the word "brachiosaurus", a countable noun, doesn't have to follow this rule. Shouldn't it be:

"It is unlikely that the brachiosaurus could have..."


"It is unlikely that brachiosauruses could have..."

  • 5
    The capitalization of Brachiosaurus is a clue. An example from the Wikipedia page: "... most size estimates for Brachiosaurus are actually for the African form." It's referring to the genus.
    – ColleenV
    Oct 18, 2017 at 19:22
  • @ColleenV: You could say "The dog is a canine animal" as readily as you could "A dog is a canine animal." Capitalization has nothing to do with it.l
    – Robusto
    Oct 19, 2017 at 0:40
  • 1
    @Robusto based on the provided context, it has everything to do with it. Dog is not a genus, but Canis is. You wouldn't say, "Dog is a canine animal," which would be an example that matches the OP's question, but you would say, "Canis is a canine animal."
    – mathewb
    Oct 19, 2017 at 1:06

1 Answer 1


As ColleenV points out in her comment, in writing it's common to refer to the scientific name of the animal as if it were a proper noun. In this case "Brachiosaurus" is the genus name for several related species such as Brachiosaurus altithorax.

In the same way you would not use "the" or pluralize the proper nouns Joe or Steve or Mary, there is no need for an article or pluralization when writing the scientific name of an organism.

Felis catus (the common domestic house cat), while often kept as an adorable companion, is actually considered one of the deadliest animals on the planet. Felis will hunt and kill almost any living thing, regardless of species, from tiny insects to larger avians nearly the cat's own size.


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