determine subfamilial affinities, however. That the fragments are the
remains of adult animals can be only surmised from the lack of bones or
teeth of large pelycosaurs in the extensive collections of the
University of Kansas from the Fort Sill locality.

If _Thrausmosaurus_ is, in fact, adult, the genus is an unusually small
sphenacodontid, and of significance both on that account and because of
the resemblance of the teeth presently known to those of its far larger
relatives.

_The Fort Sill Locality._--Peabody (1961) suggested that the fissures of
Fort Sill had been used as dens by predatory animals in the early
Permian, and that the unusually abundant bones in the fissures were the
remains of animals eaten there by these occupants. Evidence now known to
me affords an alternative explanation that is presented here as a
preliminary to a more complete study of the fauna and paleoecology of
these deposits currently being undertaken.

The suggestion that the skeletal material found in the fissures is the
remnant of the prey of other animals is questionable because of:

1. The absence of tooth marks on the fossils.

2. The recovery from the matrix of skulls and portions of
articulated skeletons that are undamaged or damaged only by
pressure after burial.

3. The rarity in the deposits of animals of larger body size than
_Captorhinus_, the exceptions being a few limb fragments and skull
fragments of labyrinthodont or pelycosaurian nature.

4. The absence of coprolites in the matrix.

If the fissures were the dens of predators, at least some and probably
many of the bones would show tooth marks. A predator feeding on other
animals would be expected to leave some evidence of its habits on the
bones of its prey. No such evidence is known to me, either from my own
examination of several thousand bones or from the reports in the
literature by others who have studied aspects of the early Permian fauna
of Fort Sill.

If the predators were larger than _Captorhinus_ and occupied the
fissures for a long enough time to account for the accumulation of the
tremendous numbers of individuals that are represented, a considerable
amount of the skeletal material of the larger animals would be present
in the fissure deposits. Even if for some reason the predators died in
areas other than within the fissures, thereby accounting for the absence
of large bones, coprolites should appear in the d