THE ANCESTRY OF THE EDENTATES ^ 



AS ILLUSTRATED BY THE SKELETON OF HapalopS, A TERTIARY ANCESTOR 

 OF THE GROUND SLOTHS 



By ]V. D. Matthew 



THE tree sloths, aiitetiters and armadillos which inhabit the forests of 

 South America are relics of a group of animals which played a very 

 important part in the mammalian life of that continent during the 

 Age of Mammals. These are the Edentates, animals of very diverse pro- 

 portions and habits but all having in common a number of anatomical 

 peculiarities, so that they are grouped into a single order. The first of these 

 peculiarities, as indicated by the name, is the absence of teeth, or at least 

 their imperfection, for when present they have no true enamel: anteaters 

 are entirely toothless, while tree sloths and armadillos have simple peglike 

 teeth, imperfect in comparison with the complex grinders of higher mammals. 

 A second peculiar feature of Edentates is the thick heavy tail, almost like 

 that of a reptile. 



The tree sloths live wholly in the tops of trees, hanging upside down 

 from the branches, and feeding on the foliage. The anteaters live partly 

 in the trees, partly on the ground, and feed upon ants and other insects. 

 The armadillos are terrestrial animals and great burrowers, eating carrion, 

 insects and maggots. They are protected by bony plates arranged in a 

 series of rings and by the habit of coiling in the pre :ence of danger into a ball 

 whose bony surface is impenetrable to the attacks of ordinary Carnivora. 



At about the time when man first appeared on earth (so far as geology 

 teaches) that is in the Pleistocene Epoch, there were living in South America 

 great numbers, not only of armadillos, and presumably anteaters and tree 

 sloths, but also of two related groups of Edentates of very much larger size, 

 the ground sloths and the glyptodonts, both now extinct. Some of these 

 were of huge bulk, and all of them at that time, large animals. The ground 

 sloths, huge, terrestrial, foliage-eating animals are illustrated by the central 

 group in the Quaternary hall. They are nearest to the tree sloths, but in a 

 few features they approach the anteaters. The glyptodonts were more or 

 less related to the armadillos, but of very great size with a solid carapace 

 over the body, the feet short, round, hoofed instead of clawed, and the teeth 

 elaborated into a complex mechanism for grinding food, instead of the 

 simple peglike grinders of the armadillos. They suggest in their outer 

 form a gigantic land tortoise, and have been called "tortoise armadillos." 



These strange-looking animals appear to have evolved in South America 



' Dr, Matthew's article on the "'Ancestry of the Edentates" is published a.s a separate 

 with further illustrations and without omissions made necessary in this Journal because 

 of lack of space This separato is for sale at the ^Museum together with other separates, 

 guide leaflets and handbooks published by the institution. 



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