How many letters does the top answer for “the science of extinct animals, a branch of paleontology.” have?

The most common answer is paleozooelogy (13 letters).

Crossword clue: the science of extinct animals, a branch of paleontology.

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

paleozooelogy 13 letters web-def

The science of extinct animals, a branch of paleontology.

paleozoology 12 letters web-def

the study of fossil animals