Complex sentence: Aikhenvald classifies Kaufman's unclassified languages apart from Morique, but leaves unclassified 15 extinct languages which Kaufman had placed in various branches of Maipurean.
Split into simpler sentences: Aikhenvald classifies Kaufman's unclassified languages apart from Morique. He does not classify 15 extinct languages which Kaufman had placed in various branches of Maipurean.