Complex sentence: The size of the phalanx bone matched what was described for the Lesser Antillean macaw by contemporary writers, and the authors therefore correlated the two, while admitting this could only be tentative, as there were no remains of the Lesser Antillean macaw to compare with.
Split into simpler sentences: The size of the phalanx bone matched what was described for the Lesser Antillean macaw by contemporary writers, and the authors therefore correlated the two. They conceded that this connection could only be tentative, as there were no remains of the Lesser Antillean macaw to compare with.