Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Q: Sentence1: a polar bear requires a cold environment. 
Sentence2: polar bears live where there are fewer animals.

A: bear
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Q: Sentence1: Arthropods Arthropods have jointed segmented exoskeletons. 
Sentence2: Insects have jointed segmented exoskeletons.

A: exoskeletons
****
Q: Sentence1: Paleontologist study the fossils of dinosuars. 
Sentence2: Scientists who find and study dinosaurs are called paleontologists.

A:
Paleontologist
****