A Remarkable Ground Sloth 



On the east side of the crater the outer rim is pierced by a narrow breach which seems to 

 form a convenient opening to the interior of the crater and doubtless has served as such to nu- 

 merous animals in the past (see PI. I, B). But this apparent haven of refuge proves to be a most 

 appalling death trap, for right across the floor, occupying the entire width of the runway, lies 

 the opening into the pit itself. This opening has a maximum diameter of 8 feet, is irregularly 

 oval in form, and leads down almost vertically into the darkness below. The skeleton of the 

 sloth was found in the depths of this natural pit, into which the animal had fallen, for a hurry- 

 ing creature which could not jump the opening would have little chance of avoiding this catas- 

 trophe. An alternative explanation is that there may have been at one time another passage into 

 the pit, now entirely obliterated, into which the sloth wandered and from which he was pre- 

 vented from emerging by the caving in of the roof of the passage. This would account for the 

 lack of any broken bones, which would almost inevitably have resulted from a vertical fall. 



The re-fused character of the walls of the sloth pit indicates its nature, namely, that it is 

 the opening of an old fumarole and thus formerly subject to intense heat. 



The descent into the pit is difficult, as it is necessary to use a rope, taking advantage of 

 occasional irregularities in the wall for foot rests. The descent is nearly vertical for the first 

 forty feet (see Fig. 2). From the first landing the pipe continues down irregularly by a series 

 of steep slopes, nearly horizontal stretches, and vertical drops, and the diameter varies greatly. 

 Fifty feet below the surface there is a large cavernous chamber, from which two passages lead 

 down, one vertically, the other by a tortuous route. These passages converge about twenty-five 

 feet below in another chamber twenty or thirty feet across. The floor of this room is sloping and 

 is heaped high with bat guano, the accumulation of centuries. 



Several blind openings start downward from this chamber ; but the main passageway leads 

 downward by a moderate slope to a second large room some fifteen feet in width by thirty in 

 length. This also contains a large quantity of bat guano. The sloth skeleton was found on the 

 floor of this room, almost completely buried in the dry, loose guano, and at a distance of about 

 one hundred feet vertically below the mouth of the pit. A short distance below the sloth cham- 

 ber is another enlargement of the fumarole pipe, below which the opening is effectively closed. 



Skeletons of coyotes, a bobcat, and other animals were found lying on top of the 

 guano, apparently recent victims of the death trap. The sloth, together with such other 

 animals as may be found buried in the guano, is evidently much older, as it has 

 Pleistocene affinities. Any creature which falls into the opening of the pit is doomed, 

 as escape by any means other than flight seems utterly impossible. From the size of 

 the opening, however, our specimen is about the largest animal which would be 

 caught. The chance of finding a Megatherium or even a Mylodon preserved in the 

 guano seems remote. Nevertheless our projected exploration of the cavern may yield 

 interesting results, among others the finding of the fellow victim that gnawed most of 

 the hide from the body of the sloth, leaving teeth marks that are still plainly visible. 



Falling into the pit would not necessarily result in broken bones, as the sloth 

 with his large claws probably retarded his fall by clinging to irregularities in the 

 walls. After he reached the first landing forty feet down, he may have descended the 

 remainder of the way of his own accord while searching for a means of escape. He 

 could not, however, ascend unaided even from the first landing. 



