Complex sentence: Some of Sibley's results-such as the close relationship of galliform birds and waterfowl and their distinctness from other neognaths, have been verified, others, such as the inclusion of diverse groups into the Ciconiiformes have turned out to be very much in error.
Split into simpler sentences: Some of Sibley's results--such as the close relationship of galliform birds and waterfowl and their distinctness from other neognaths--have been verified. Other results such as the inclusion of diverse groups into the Ciconiiformes have turned out to be very much in error.