He is an expert in topology.

I am very interested in sociolinguistics.

He is an expert in biophysics.

He is an expert in algebraic geometry.

He is an expert in ethology, and his research is highly regarded worldwide.

I am majoring in developmental biology at university.

He is majoring in oenology.

Paleogeography is a study that researches the past geographical conditions of the Earth.

Paleoecology is a field of study that investigates the relationship between past organisms and their environment.

He is an expert in paleozoology and has a deep knowledge about the ecology of dinosaurs.