He is an expert in paleontology.

He is an expert in malacology, focusing particularly on the study of snails.

He is an expert in toxicology and conducts many studies.

He is majoring in zoology at university.

I am majoring in biology at university.

He is an expert in theoretical physics.

A palatal consonant is produced when the middle part of the tongue contacts or approaches the hard palate.

He couldn't say anything about issues outside of his field of expertise.

There are many different specialty stores in this town.

He is a specialist fool, with no interest in anything outside his field.