Complex sentence: His successor at the Lyceum was Theophrastus, and he wrote valuable books describing plant and animal life, and his works are regarded as the first to put botany and zoology on a systematic footing.
Split into simpler sentences: His successor at the Lyceum was Theophrastus, who wrote valuable books describing plant and animal life. His works are regarded as the first to put botany and zoology on a systematic footing.