The probable explanation was that larger-beaked birds had an advantage in eating the last tough seeds that remained.
(the last tough seeds; remained; ) (The probable explanation; was; that larger-beaked birds had an advantage in eating the last tough seeds) Context(The probable explanation was,List([0, 28))):(larger-beaked birds; had; an advantage) Context(The probable explanation was larger - beaked birds had,List([0, 57))):(larger-beaked birds; had an advantage in eating; the last tough seeds that remained)
The probable explanation was,List([0, 28)) The probable explanation was larger - beaked birds had,List([0, 57))
the last tough seeds The probable explanation larger-beaked birds larger-beaked birds
remained was had had an advantage in eating
that larger-beaked birds had an advantage in eating the last tough seeds
an advantage
the last tough seeds that remained