Respiratory effects [edit]. The PRG antagonizes the apneustic center, cyclically inhibiting inhalation. The PRG limits the burst of action potentials in the phrenic nerve, effectively decreasing the tidal volume and regulating the respiratory rate.espiratory effects [edit]. The PRG antagonizes the apneustic center, cyclically inhibiting inhalation. The PRG limits the burst of action potentials in the phrenic nerve, effectively decreasing the tidal volume and regulating the respiratory rate.
Because the ones at the bottom, the animals would have died first and soil would have covered them building a cliff and the fossils up top would have died later. 3 people found this useful.
Find a rock layer that has at least one of the fossils you found in the oldest rock layer. This rock layer would be younger as indicated by the appearance of new fossils in the rock stratum. Keep in mind that extinction is forever.elative dating tells scientists if a rock layer is older or younger than another. This would also mean that fossils found in the deepest layer of rocks in an area would represent the oldest forms of life in that particular rock formation.