Complex sentence: This system may allow the animals to remain submerged for a longer period, but this explanation has been questioned; other possible reasons for the peculiar circulatory system include that it assists with thermoregulatory needs, reduces pulmonary oedema, or speeds recovery from metabolic acidosis.
Split into simpler sentences: This system may allow the animals to remain submerged for a longer period, but this explanation has been questioned. Other possible reasons for the peculiar circulatory system include that it assists with thermoregulatory needs, reduces pulmonary oedema, or speeds recovery from metabolic acidosis.