Paleontology is the study of fossils, therefore a paleontologist is a person who studies fossils.
I have not heard of palieontologist.
A paleontologist is someone who studies prehistoric life
Richard Leakey was a paleontologist.
Scientists who study all forms of life that existed in former geologic periods, by fossils.
A palaeontologist is a person who studies palaeontology - the study of the life forms existing in prehistoric or geologic times, especially as represented by fossils.
A palaeobiologist is a person who studies palaeobiology - the scientific study of prehistoric life, especially of those aspects relating to living systems.
A palaeoichnologist is a person who studies palaeoichnology - the study of the discovery of trace fossils preserved in ancient rocks.