In sentence case, no capital letters are used (e.g., brown bear, ray-finned shark), except for proper names (e.g., North American beaver, Roosevelt's elk). Names of higher categories of animals are always written in sentence case (e.g., kangaroo rat, river martin).

Do you capitalize the name of a species?

Historically, species names derived from proper names were capitalized, but modern practice is not to capitalize even those. Note that the genus and species (and subspecies and variety) are italicized. ... The names of the various levels of classification (like, class, order family, genus) are not capitalized.

Is kangaroo a common or proper noun?

A member of a family of large marsupials with strong hind legs for hopping, mainly found in Australia, scientific name macropod.