Complex sentence: A recent study on the heart rate's contribution to the regulation of the baimans' body temperature showed an increase in heart rate as the temperature increased, and it lowers once the temperature lowered.
Split into simpler sentences: A recent study has been done on the heart rate's contribution to the regulation of the Caimans' body temperature. The results showed an increase in heart rate as the temperature increased, and that it would lower once the temperature lowered.