Australopithecus is a genus, it has no plural. You could speak of the Australopithecines though, which are the extinct human-like primates of the genus.
The plural of squirrel is squirrels.
The plural of zoo is zoos. The plural possessive form of zoos is zoos'.
The plural form of rat is 'rats'.
The plural possessive form of lion is lions'.
The plural is fossae.
The plural form of Australopithecus is Australopithecines.
The species from which H. sapiens evolved was probably some form of Australopithecus, possibly Australopithecus afarensis.
There is no plural form. Do and Do not are verbs
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "was" is "were."
The plural form of "I" is "we."
The plural form of "is" is "are."
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.
"Groceries" is the plural form of "grocery."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
The plural form of the demonstrative pronoun 'that' is those.