Thylacosmilus is a marsupial, and smilodon is a mammal. thylacosmilus and smilodon both have saber teeth, but they do not share an ancestor that had saber teeth. what are saber teeth for these organisms?

Analogous traits are traits shared by different species having a similar function but not  acquired from a common ancestor.

In this case, the Thylacosmilus and Smilodon have a similar trait, which is saber teeth. It is given that saber teeth are not found in the ancestors of the Thylacosmilus and Smilodon. So, this trait is evolved differently in both the organism, but share the same function.

Hence, it is an example of analogous character.

they fuse to form they have half as many chromosomes as a somatic cell of the same individual. b

b. lithosphere, asthenosphere, mesosphere   is the answer most likely