88 EXTINCT MONSTERS. 
other parts, such as limb-bones, but more especially the bones of 
which the backbone is composed (known as vertebrz). ‘These 
are very important. The veteran anatomist, Professor Owen, has 
said, ‘‘If I were restricted to a single specimen on which to 
deduce the nature of an extinct animal, I should choose a 
vertebra to work out a reptile, and a tooth in the case of a 
mammal.” Seven or eight different ‘‘ characters,” he says, may 
be deduced from a reptilian vertebra. It is, of course, impossible 
Zz 
Fic. 20.—Tooth of Iguanodon, with the apex slightly worn. (From the 
Wealden Beds of Tilgate Forest. Natural size.) 1. Front aspect, showing 
the longitudinal ridges and serrated margins of the crown. 2. View of the 
back, or inner surface of the tooth. a. Serrated margins. 4. Apex of the 
crown worn by use. 
for any one to reconstruct an entire animal from a single bone or 
a few teeth, yet such fragments indicate in a general way the 
nature of a lost creation and its position in the animal kingdom. 
It is all the more important to give to the general reader this 
warning, because an impression seems still to remain in the 
popular mind that Owen could and did restore extinct types from 
a single bone er a single tooth; but no anatomist would attribute 
to any mortal man such superhuman power. Let us, therefore, 
