A shared ancestral character is A) a character that originated in an ancestor of the B) shared by all mammals but not found in the new C) an evolutionary novelty unique to a clade D) an outgroup characters

The correct answer is option A) "a character that originated in an ancestor of the taxon".

Explanation:

A shared ancestral character is defined as a character that originated in an ancestor of the taxon. This type of characters contrasts with shared derived characters, which are characters that develop within the taxon and do not include all the ancestors of a given phylogenetic tree. For instance, the presence of four limbs is a shared ancestral character for a large group of animals, including amphibians, birds, mammals, turtles, crocodiles, among others.