Complex sentence: Whether their hooked bill means that unlike "Confuciusornis"-probably an omnivore that at least occasionally caught fish -, "Changchengornis" fed on fruit is not known.
Split into simpler sentences: Whether their hooked bill means that they were probably omnivorous, unlike Confuciusornis, they probably at least occasionally caught fish. Whether "Changchengornis" fed on fruit is not known.