Scientists have discovered that once a mammal has become fully aquatic, it passes a threshold that makes a return to terrestrial landscapes almost impossible.
All life started in the sea. Transitioning back to semi-aquatic or fully aquatic has happened many times. Is it possible to transition back? According to these researches, it seems like a one way gate. The types of changes that land animals make to become fully aquatic again seem to lock a lineage into the water forever. Increased body mass and carnivorous diet are helpful going back to water but make it really hard to go back to land and redevelop mobility.
All life started in the sea. Transitioning back to semi-aquatic or fully aquatic has happened many times. Is it possible to transition back? According to these researches, it seems like a one way gate. The types of changes that land animals make to become fully aquatic again seem to lock a lineage into the water forever. Increased body mass and carnivorous diet are helpful going back to water but make it really hard to go back to land and redevelop mobility.