DINOSAURS 165 
feet in length. It will be seen that the fore limbs are small in 
comparison to the hind limbs. A remarkable feature of the hand 
is the large pointed bone at the end of the thumb, forming a kind 
of spur. The conical shape of this bone found by Dr. Mantell, 
who had no clue to its place in the skeleton, led him to suppose 
that it was a horn answering to that of a rhinoceros—a conclusion 
which Professor Owen refused for various reasons to accept. The 
latter concluded that it belonged to the hand, and now we see 
Fic. 55.—Skull and skeleton of Iguanodon Mantelli. (After Dollo.) 
that he was right. It has been suggested that the spur was a 
weapon of offence, and that, when attacked, an Iguanodon may 
have seized its aggressor in its short arms, and made use of the spur 
asadagger. But this is only conjecture, and perhaps the spur may 
have been useful in seizing and pulling down the foliage and 
branches of trees, or in grubbing them up by the roots. Detached 
specimens of this curious bone may be seen among the other 
