82 Prof. Owen on the Reptilian Fossils of South Africa. 



Bird or Turtle. Yet if we consider the fact teleologically, or in its relations to 

 the exigences and convenience of the living animal, the wisdom and beneficence 

 of the principle is apparent, and the departure from the ordinary rule manifests a 

 power transcending the trammels of scientific system. The teeth of the Dicy- 

 nodon being but two in number, and their use to the animal indicated by their 

 unusual size to be of unusual importance, the inconvenience and detriment that 

 must have ensued from frequent shedding and replacement is very obvious ; we 

 may readily conceive it to have been incompatible with their functions, and there- 

 fore abrogated in favour of another mode of renovation which is abnormal in Rep- 

 tiles, simply, perhaps, because the form, proportions and function of such tusks 

 were unique, and are now no longer manifested in a cold-blooded class. 



Some observations may be naturally expected in reference to the probable use 

 of the tusks to the Dicynodons, and the mode of life of those ancient and most 

 remarkable Saurians. In the Mammalian class, where alone we now find the 

 analogous instruments, tusks are usually given as weapons of offence and defence, 

 — an office exemplified in the hornless Musk-deer, the Boar, and in the large canine 

 teeth of the Carnivora. The Elephants use their tusks chiefly, though not exclu- 

 sively, as lethal weapons : the Walrus is said to apply his tusks to aid in clamber- 

 ing over icebergs, as well as in combat and defence : the Dugong is supposed to 

 Avear the exserted points of the tusks in detaching fuci for food. Such an office at 

 first suggests itself as a very probable one in regard to tusks descending, like those 

 of the Dugong, from the upper jaw, and combined with edentulous and probably 

 horny mandibles like those of a fucivorous Turtle. 



On inspecting the remains and the impressions of the tusks in the fossils under 

 consideration, and especially in the almost entire skull of the Dicynodon lacerticeps, 

 we perceive that these weapons are sharp-pointed, and present no trace of that 

 obliquely beveled or chisel-shaped extremity which is produced by habitual appli- 

 cation in acts of obtaining daily food, as, for example, in the protruded extremities 

 of the tusks of the Dugong and the incisors of the Rodents. The tusks of the 

 Dicynodon, though similar, in their origin from maxillary bones and downward 

 direction, to the tusks of the Walrus, are so much shorter, at least in the single 

 specimen in which their entire length is shown, that they could not be available in 

 locomotion. I conclude therefore from their shape, proportional length, sharp 

 points and dense texture, that the tusks of the Dicynodon were applied by the 

 living animal either for the purpose of kilhng its prey, or of defending itself from 

 its foes, or in both acts ; and that they were offensive and defensive arms. 



A further insight into the habits and mode of life of the Dicynodons may reason- 

 ably be expected to follow the examination of the skeleton of the trunk and the 

 organs of locomotion. This will form the subject of a subsequent memoir ; but I 



