to higher
efficiency of the mouth parts in catching and swallowing prey (see p.
482).

ENVIRONMENT

The coelacanth fishes from the Rock Lake shale are part of the varied
fauna collected from Garnett. Peabody (1952:38) listed many elements of
the fauna and flora, and concluded that the deposits are of lagoonal
origin. In addition to numerous invertebrates (including microfossils)
and arthropods, a number of vertebrates other than coelacanths have been
found. These include at least one kind of shark, _Hesperoherpeton
garnettense_ Peabody, one or more kinds of undescribed labyrinthodonts
and the reptiles _Petrolacosaurus kansensis_ Lane, _Edaphosaurus ecordi_
Peabody, and _Clepsydrops_ (undescribed species). This is indeed a rich
vertebrate fauna, and the earliest known reptilian fauna. Much of the
rock contains plant remains. The flora that has been identified is
adapted to growing in a well-drained soil; although it contains some
elements considered characteristic of the Permian, it is of
Pennsylvanian age (Moore _et al._, 1936). Peabody (1952:38-39) discusses
the features of these lagoonal sediments. Much of the fauna and flora
suggests continental origin, but the many marine invertebrates at some
horizons indicate that at least some of the sediments were of marine
origin.

Little can be said about the actual environment of the living fishes of
the genus _Synaptotylus_. Remains of these fishes occur in layers
containing marine invertebrates, as well as in those containing plant
remains and vertebrate skeletal parts, and in those nearly completely
composed of dark carbonaceous material. Most of the remains are
fragmentary and consist of isolated bones, isolated scales, and
dissociated skulls; only one specimen and half of another are nearly
complete. Many published statements on _Rhabdoderma_, a related genus,
indicate both marine and fresh-water environments. Wehrli (1931:115)
regarded _Rhabdoderma elegans_ (Newberry) as a euryhaline species, and
cited its occurrence with both marine and fresh-water fossils. Aldinger
(1931:199) also found this to be the case with other species, and Fiege
(1951:17) quotes others as giving the same information. Keller
(1934:913) thought that few Carboniferous fishes were exclusively
marine, and stated that the majority of them became adapted to fresh
water during the late Carboniferous. Later, Schaeffer (1953:175) stated
that all Carboniferous and Permian coelacanths were fresh-wat