Just checking: no-one’s bored of brachiosaurs yet, are they? Thought not.  Right, then, here we go! Greg Paul’s (1988) study of the two “ Brachiosaurus ” species — the paper that proposed the subgenus Giraffatitan for the African species — noted that the trunk is proportionally longer in Brachiosaurus than in Giraffatitan due to the greater length of its dorsal centra.