Title: A New Genus of Pennsylvania Fish (Crossoperygii, Coelacanthiformes) from Kansas
Author: Echols, Joan
Language: English
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UNIVERSITY OF KANSAS PUBLICATIONS
MUSEUM OF NATURAL HISTORY

Volume 12, No. 10, pp. 475-501, 7 figs.
October 25, 1963

A New Genus of Pennsylvanian Fish (Crossopterygii, Coelacanthiformes)
from Kansas

BY

JOAN ECHOLS

UNIVERSITY OF KANSAS
LAWRENCE
1963


UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Theodore H. Eaton, Jr.


~Volume 12, No. 10, pp. 475-501, 7 figs.~
~Published October 25, 1963~

UNIVERSITY OF KANSAS
Lawrence, Kansas

PRINTED BY
JEAN M. NEIBARGER, STATE PRINTER
TOPEKA, KANSAS
1963

[Transcriber's Note: Words surrounded by tildes, like ~this~ signifies
words in bold. Words surrounded by underscores, like _this_, signifies
words in italics.]



A New Genus of Pennsylvanian Fish (Crossopterygii, Coelacanthiformes)
from Kansas

BY

JOAN ECHOLS


INTRODUCTION

In 1931 and 1932, H. H. Lane, C. W. Hibbard and W. K. McNown collected
the specimens that Hibbard (1933) described and made the basis of two
new species. These were from the Rock Lake shale member of the Stanton
formation, six miles northwest of Garnett, Anderson County, Kansas. In
1954, from a locality (KAn-1/D, see page 480) approximately one fourth
mile southwest of the first locality, specimens were quarried by F. E.
Peabody, R. W. Wilson and R. Weeks. In 1955 R. R. Camp collected
additional blocks of Rock Lake shale from this second locality. Study of
all of the materials from the above mentioned localities reveals the
existence of an hitherto unrecognized genus of coelacanth. It is named
and described below.

I wish to thank Prof. Theodore H. Eaton, Jr., for suggesting the project
and for much helpful advice. I am indebted to Dr. E. I. White of the
British Museum (Natural History) for furnishing a cast of the
endocranium of _Rhabdoderma elegans_ (Newberry) for comparison, and to
Drs. Donald Baird (Princeton University), Bobb Schaeffer (American
Museum of Natural History) and R. H. Denison (Chicago Natural History
Museum) for loans and exchanges of specimens for comparison. I am
grateful to Dr. Bobb Schaeffer for advice on the manuscript. Mr. Merton
C. Bowman assisted with the illustrations. The study here reported on
was made while I was a Research Assistant supported by National Science
Foundation Grant G-14013.


SYSTEMATIC DESCRIPTIONS

Subclass CROSSOPTERYGII

Superorder COELACANTHI

Order Coelacanthiformes

Suborder DIPLOCERCIDOIDEI

Family DIPLOCERCIDAE

Subfamily ~Rhabdodermatinae~, new subfamily

     _Type genus._--_Rhabdoderma Reis_, 1888, Paleontographica,
     vol. 35, p. 71.

     _Referred genus._--_Synaptotylus_ new, described below.

     _Horizon._--Carboniferous.

     _Diagnosis._--Sphenethmoid region partly ossified, and
     consisting of basisphenoid, parasphenoid, and ethmoid
     ossifications; paired basipterygoid process and paired
     antotic process on basisphenoid; parasphenoid of normal
     size, and closely associated with, or fused to,
     basisphenoid; ethmoids paired in _Rhabdoderma_ (unknown in
     _Synaptotylus_).

_Discussion._--Because of the great differences in endocranial structure
between the Devonian and Pennsylvanian coelacanths, they are here placed
in new subfamilies. The two proposed subfamilies of the family
Diplocercidae are the Diplocercinae and the Rhabdodermatinae. The
Diplocercinae include those coelacanths having two large unpaired bones
in the endocranium (at present this includes _Diplocercides_ Stensiö,
_Nesides_ Stensiö and _Euporosteus_ Jaekel). The subfamily
Rhabdodermatinae is composed of coelacanths having reduced endocranial
ossification, as described in detail above, and now including
_Rhabdoderma_ Reis and _Synaptotylus_ n. g.

Members of this subfamily differ from those of the subfamily
Diplocercinae in having several paired and unpaired elements in the
sphenethmoid region of the endocranium, instead of only one larger
ossification. They differ from those of the suborder Coelacanthoidei in
the retention of basipterygoid processes.

_Synaptotylus_ is more closely related to _Rhabdoderma_ than to the
Diplocercines because the anterior portion of the endocranium contains
only a basisphenoid, parasphenoid, and probably ethmoids. The
sphenethmoid region was certainly not a large, unpaired unit as in the
Diplocercines. Probably the posterior part, the otico-occipital region
(not known in _Synaptotylus_), was much more nearly like that of
_Rhabdoderma_, which consisted of unpaired basioccipital and
supraoccipital, and paired prootics, exoccipitals, and anterior and
posterior occipital ossifications (Moy-Thomas, 1937: figs. 3, 4).
Moy-Thomas (1937:389) points out that in _Rhabdoderma_ the occipital
region is "considerably more ossified" than in any coelacanths other
than the Devonian forms. Berg (1940:390) thought that the Carboniferous
coelacanths should be placed in a separate family because they did not
have two large, unpaired bones in the endocranium. _Rhabdoderma_ and
_Synaptotylus_ represent another stage in evolution of the endocranium
in coelacanths, and, if classification is to be based on endocranial
structure, then this stage (represented by the two genera) may later be
given family rank as Berg suggested. Because _Rhabdoderma_ and
_Synaptotylus_ have only part of the sphenethmoid region ossified and
because they retain basipterygoid processes, they are considered to be
related and are included in the subfamily Rhabdodermatinae.


~Synaptotylus~, new genus

     _Type species._--_Synaptotylus newelli_ (Hibbard).

     _Horizon._--Rock Lake shale member, Stanton formation,
     Lansing group, Missouri series, Upper Pennsylvanian.

_Diagnosis._--Late Pennsylvanian fishes of small size, having the
following combination of characters: on basisphenoid, knoblike antotic
processes connected by a low ridge to basipterygoid processes; entire
ventral surface of parasphenoid toothed; anterior margin of parasphenoid
notched and no evidence of hypophyseal opening. Dermal bones of skull
smooth or with low, rounded tubercles and striae; fronto-ethmoid shield
incompletely known but having one pair of large rectangular frontals
with posterolaterally slanting anterior margins; intertemporals large,
the lateral margins curving laterally; postorbital triangular, apex
downward; subopercular somewhat triangular; squamosal carrying sensory
canal that curves down posteriorly and extends onto a ventral
projection; opercular generally triangular; supratemporals elongate,
curving to fit lateral margin of intertemporals; circumorbital plates
lightly ossified. Palatoquadrate complex consisting of endopterygoid and
ectopterygoid (both toothed on medial surface), quadrate, and
metapterygoid, the latter smooth and having widened border for
articulation on anterodorsal margin. Pectoral girdle consisting of
cleithrum and clavicle (supracleithrum not seen); small projection on
medial surface of posterior portion of cleithrum; horizontal medial
process on clavicle. Pelvic plate bearing three anteriorly diverging
apophyses, and one denticulate ventromedian process for articulation to
opposite plate. Lepidotrichia jointed distally, but not tuberculated.
Scales oval, having posteriorly converging ridges on posterior exposed
parts.

The name refers to the most distinctive character of the genus, the
connected antotic and basipterygoid processes on the basisphenoid, and
is derived from Greek, _synaptos_--joined, _tylos_ (masc.)--knob,
projection.

_Synaptotylus_ is excluded from the advanced suborder Coelacanthoidei by
the retention of basipterygoid processes on the basisphenoid.
_Synaptotylus_ differs from _Rhabdoderma_ in several characters of the
basisphenoid, the most important being: knoblike antotic processes
(those of _Rhabdoderma_ are wider, more flattened and more dorsal in
position); small, lateral basipterygoid processes (in _Rhabdoderma_
these are larger and farther ventral in position).


~Synaptotylus newelli~ (Hibbard)

     _Coelacanthus newelli_ Hibbard, 1933, Univ. Kansas Sci.
     Bull., 21:280, pl. 27, figs. 2, 3.

     _Coelacanthus arcuatus_ Hibbard, 1933, Univ. Kansas Sci.
     Bull., 21:282, pl. 26, fig. 8; pl. 27, fig. 1.

     _Rhabdoderma elegans_ Moy-Thomas, 1937 (in part), Proc.
     Zool. Soc. London, 107(ser. B, pt. 3):399.

     _Type._--K. U. no. 786F.

     _Diagnosis._--Same as for the genus.

     _Horizon._--Rock Lake shale member, Stanton formation,
     Lansing group, Missouri series, Upper Pennsylvanian.

     _Localities._--The specimens studied by Hibbard (K. U. nos.
     786F, 787F, 788) and no. 11457 were taken from the Bradford
     Chandler farm, from the original quarry in SW-1/4, SE-1/4,
     sec. 32, T.19S, R.19E. The remainder were collected from
     University of Kansas Museum of Natural History locality
     KAn-1/D, a quarry in sec. 5, T.19S, R.19E. Both of these are
     approximately six miles northwest of Garnett, Anderson
     County, Kansas.

     _Referred specimens._--K. U. nos. 786F, 787F, 788, 9939,
     11424, 11425, 11426, 11427, 11428, 11429, 11430, 11431,
     11432, 11433, 11434, 11449, 11450, 11451, 11452, 11453,
     11454, 11455, 11457.

     _Preservation._--Preservation of many of the specimens is
     good, few are weathered, but most of the remains are
     fragmentary and dissociated. One specimen (the type, no.
     786F) and half of another were nearly complete. Specimens
     are found scattered throughout the Rock Lake shale (see p.
     498).

     _Morphology._--Terminology used for bones of the skull is
     that of Moy-Thomas (1937) and Schaeffer (1952).


_Endocranium and parasphenoid_

[Illustration: FIG. 1. _Synaptotylus newelli_ (Hibbard). Restoration of
the basisphenoid, based on K. U. no. 9939, × 5. A, lateral view, B,
posterior view, C, ventral view.]

The basisphenoid (see fig. 1) has been observed in only one specimen (K.
U. no. 9939) in posterodorsal and ventral views. The basisphenoid,
although somewhat crushed, appears to be fused to the parasphenoid. Both
antotic and basipterygoid processes are present, and are connected by a
low, rounded ridge. The antotic processes are large, bulbar projections.
These processes in _Rhabdoderma_ are wider and more flattened
(Moy-Thomas, 1937:figs. 3, 4). The antotic processes are at mid-point on
the lateral surface, not dorsal as in _Rhabdoderma_, and both the
processes and the ridge are directed anteroventrally. The basipterygoid
processes are smaller, somewhat vertically elongated projections,
situated at the end of the low connecting ridge extending
anteroventrally from the antotic processes, and are not basal as are
those of _Rhabdoderma_. The sphenoid condyles, seen in posterior view,
issue from the dorsal margin of the notochordal socket. The margins of
the socket are rounded, and slope down evenly to the center. A slight
depression situated between and dorsal to the sphenoid condyles is
supposedly for the attachment of the intercranial ligament (Schaeffer
and Gregory, 1961:fig. 1). The alisphenoids extend upward,
anterodorsally from the region above the sphenoid condyles, and may
connect to ridges on the ventral surface of the frontals. The lateral
laminae are not preserved, and their extent is unknown.

In viewing the changes in the endocranium of Carboniferous and Permian
coelacanths, it would be well to consider the mechanical relationship of
the loss of the basipterygoid processes to the effect on swallowing
prey. Evidently many of the coelacanths, _Latimeria_ for example, are
predators (Smith, 1939:104); to such fishes a more efficient catching
and swallowing mechanism would be an adaptive improvement. Stensiö
(1932:fig. 14) presents a cross section of the ethmosphenoid moiety of
the endocranium of _Diplocercides kayseri_ (von Koenen) showing the
metapterygoid of the palatoquadrate loosely articulated to both the
antotic and basipterygoid processes. According to Tchernavin (1948:137)
and Schaeffer and Rosen (1961:190) the swallowing of large prey depends
on the ability of the fish to expand its oral cavity by allowing the
posteroventral portion of the palatoquadrate and the posterior end of
the mandible to swing outward. Where the palatoquadrate articulates with
the basisphenoid at the antotic and basipterygoid processes, as in the
Devonian coelacanths, it can not swing so far laterally as where it
articulates with only the dorsal, antotic process. Perhaps the loss of
the basipterygoid articulation reflects the development of a more
efficient mechanism for swallowing prey in these fishes. Schaeffer and
Rosen (1961:191, 193) show that in the evolution of the actinopterygians
several changes improved the feeding mechanism: some of these changes
are: (1) freeing of the maxilla from the cheek, giving a larger chamber
for the action of the adductor mandibulae; (2) development of a coronoid
process on the mandible; and (3) increase in torque around the jaw
articulation. In coelacanths, at least some comparable changes occurred,
such as: (1) loss of the maxillary, thus increasing the size of the
adductor chamber; (2) development of the coronoid bone, affording a
greater area for muscle attachment; (3) development of an arched dorsal
margin on the angular; (4) modification of the palatoquadrate complex,
with resultant loss of the basipterygoid processes. In _Synaptotylus_
the basipterygoid processes are small, not basally located, and perhaps
not functional. A more efficient feeding mechanism developed rapidly
during the Carboniferous and has remained almost unaltered.

[Illustration: FIG. 2. _Synaptotylus newelli_ (Hibbard). Restoration of
the parasphenoid, based on K. U. nos. 9939, 11451, × 5. A, ventral view,
B, dorsal view and cross sections.]

The parasphenoid (see fig. 2) is a shovel-shaped bone having a wide
anterior portion and a narrower posterior portion of nearly uniform
width. Most of the ventral surface is covered with minute granular
teeth. The anterior margin is flared and curved posteromedially from the
lateral margin to a median triangular projection. The lateral margins
curve smoothly from the greatest anterior width to the narrow central
portion, where the margins become somewhat thickened and turned
dorsally. Posterior to this the lateral margins are probably nearly
straight. The external surface of the anterior section is nearly flat
and has a central depressed area the sides of which slope evenly to the
center. The internal surface is smooth and centrally convex. Because of
the fragmentary nature of all four observed specimens, total length was
not measured but is estimated to be 15 to 20 mm. The opening of the
hypophyseal canal was not present, possibly because of crushing.
Ethmoidal ossifications were not preserved in any of the specimens
studied. The parasphenoid differs from that of _Rhabdoderma elegans_
(Newberry) in being more flared and widened anteriorly and more concave
centrally.


_Dermal bones of the skull_

Various portions of the cranial roof are preserved in several specimens
(see fig. 3). For comparisons with _Rhabdoderma elegans_, see Moy-Thomas
(1937:fig. 1).

The premaxillaries and rostral elements are not preserved in any of the
specimens. Only one pair of relatively large frontals have been
observed; they are 5.5 to 9.0 mm. long and 2.0 to 3.5 mm. wide. These
are nearly flat bones, with the greatest width posteriorly 0.1 to 1.0
mm. wider than the anterior portion. The midline suture is straight, the
lateral margins are nearly straight, the anterior margin slopes evenly
posterolaterally, and the posterior margin is slightly convex to
straight. The anterior margin in _R. elegans_ is essentially straight.
Ornamentation consists of sparse, unevenly spaced, coarse tubercles or
short striae. In one specimen both bones have small clusters of
tubercles near the lateral margins and about 2.0 mm. from the posterior
margin. None of these bones has alisphenoids or ridges on the ventral
surface, as Stensiö (1921:65, 97) described for _Wimania_ and _Axelia_.

[Illustration: FIG. 3. _Synaptotylus newelli_ (Hibbard). Diagram of the
dermal bones of the skull, in lateral view, based on K. U. nos. 788 and
11432. × 2-1/2 approximately.]

Only six supraorbitals have been preserved (see fig. 3). These are
nearly square, flat, thin bones lying nearly in place adjacent to a
frontal on K. U. no. 788. The smallest is anterior; the margins of all
are nearly straight. The bones are unornamented. Each bears a pore of
the supraorbital line just below the midline. The supraorbitals of _R.
elegans_ have a triangular outline and do not bear pores.

Intertemporals (fig. 3) on several specimens vary from approximately 9.0
to 15.0 mm. in length, 2.0 to 2.7 mm. in anterior width, and increase to
4.5 to 8.0 mm. in maximum posterior width. The midline suture is
straight, the anterior margin is concave and the lateral margin proceeds
laterally in a concave curve to the widest portion. In _R. elegans_ only
the anterior half of the corresponding margin is concave. The posterior
margin is slightly rounded and slopes anteriorly toward the lateral
margin. Ornamentation is usually of randomly oriented tubercles and
striae, although striae are more common in the posterior third and may
be longitudinal, whereas tubercles occur mainly on the anterior section.
No evidence of sensory pores, as seen on the intertemporal of _R.
elegans_, has been found.

The supratemporals were observed on only one specimen (K. U. no. 788),
(fig. 3). Sutures were difficult to distinguish but the medial margin is
presumed to curve to fit and to articulate with the lateral margins of
the intertemporals. Lateral margins are smoothly curved but the anterior
and posterior margins were broken off. There appears to be no
ornamentation on this bone. The supratemporals are much more elongated
and curving than those in _R. elegans_.

The cheek region is nearly complete in one specimen (K. U. no. 788), and
scattered parts occur in a few others (see fig. 3). The lacrimojugal of
no. 788 is elongate, with both ends curving dorsally. It differs from
the lacrimojugal in _R. elegans_, in which the anterior end extends
anteriorly and is not curved dorsally. The posterior and anterior
margins are not preserved; the greatest height appears to be posterior.
Pores of the suborbital portion of the infraorbital sensory canal are
seen on the dorsal surface of the bone. In _R. elegans_ the pores are on
the lateral surface. A section of the lacrimojugal on specimen no.
11425, broken at both ends, shows a thin layer of bone perforated by the
pores and covering a groove for the canal within the dorsal margin of
the bone. Both specimens are unornamented.

A nearly complete postorbital (fig. 3) on specimen no. 788 is nearly
triangular, with the apex ventral. The concave anterior margin bears
pores of the postorbital part of the infraorbital line. Ornamentation
consists of widely spaced, coarse tubercles.

Part of one squamosal is preserved. It is somewhat triangular and its
apex is ventral. This bone is associated with the postorbital,
subopercular and lacrimojugal on no. 788. The preopercular sensory line
passes down the curving ventral margin of this bone, and extends
ventrally onto a narrow projection. A low ridge, nearly vertical, passes
dorsally from about mid-point of the canal to the dorsal portion. The
anterior margin is nearly straight, the ventral margin is concave, and
the dorsal margin is convex dorsally but may be incomplete. Perhaps the
squamosal and preopercular are fused. The surface appears smooth; the
view may be of the medial side. The squamosal of _R. elegans_ is nearly
triangular and notably different from that of _Synaptotylus newelli_.

The subopercular (fig. 3) shows closely spaced tubercles on the lateral
surface. The bone is an elongated, irregular triangle with the apex
pointing anterodorsally. The margins are incomplete, except for the
concave, curving anterior margin.

Numerous operculars (fig. 3) occur in the suite of specimens, both
isolated and nearly in place. Each is subtriangular; the apex of the
triangle is ventral. A slight convexity projects from the anterodorsal
border. The posterior margin is broadly but shallowly indented.
Otherwise the margins are smooth. Maximum height ranges from 8.0 to 11.0
mm., and maximum width from 8.0 to 13.0 mm. Ornamentation varies from a
few widely spaced, randomly oriented tubercles to closely spaced
tubercles merging posteriorly into striae. On some specimens these are
parallel to the dorsal border, and oblique in the central portion. On
the posterior margins of several operculars the striae break up into
tubercles. A few operculars have closely spaced tubercles over much of
the surface. The internal surface is smooth.


_Visceral skeleton_

The palatoquadrate complex, best seen on K. U. no. 9939 (fig. 4),
consists of endopterygoid, ectopterygoid, metapterygoid and quadrate. No
trace of epipterygoids, dermopalatines or autopalatines, such as
Moy-Thomas (1937:392, fig. 5) described for _Rhabdoderma_, has been
observed.

The endopterygoid has a long, ventral, anteriorly-directed process, and
an anterodorsal process that meets the metapterygoid in forming the
processus ascendens. The suture between the endopterygoid and
metapterygoid, seen in lateral view, is distinct in some specimens and
has an associated ridge; these bones appear to be fused in others,
without regard to size. This suture curves dorsally from a point
anterior to the quadrate and passes anterodorsally to the extremity of
the processus ascendens. The suture is visible on the medial side only
near the processus ascendens, for it is covered by a dorsal, toothed
extension of the endopterygoid. The endopterygoid has a smooth lateral
surface; the medial surface is covered with tiny granular teeth, in
characteristic "line and dot" arrangement. The teeth extend onto the
ventral surface of the ventral process.

[Illustration: FIG. 4. _Synaptotylus newelli_ (Hibbard). Restoration of
the palatoquadrate complex, based on K. U. no. 9939, × 5. A, medial
view, B, lateral view.]

Two long, narrow, splintlike bones covered on one surface with granular
teeth are interpreted as ectopterygoids. These are 13.0 and 16.0 mm.
long and each is 1.5 mm. wide. Orientation of these is unknown, but they
probably fitted against the ventral surface of the ventral process of
the endopterygoid (Moy-Thomas, 1937:fig. 5).

[Illustration: FIG. 5. _Synaptotylus newelli_ (Hibbard). A, ceratohyal,
lateral (?) view, based on K. U. nos. 11429 and 11457, × 5. B, urohyal,
based on K. U. no. 11457, × 5.]

The metapterygoid has a smooth surface in both views. The dorsal edge
has a thickened, flared margin that presumably articulated with the
antotic process of the basisphenoid. No articular surface for the
basipterygoid process has been observed.

The quadrate is distinct and closely applied to the posteroventral
margin of the complex. In medial view the margin is nearly straight and
continues to the ventral edge. The ventral surface is thickened and
forms a rounded, knoblike articular surface. In lateral view the surface
is smooth; the anterior margin is irregular (or perhaps broken on all
specimens), and proceeds in an irregular convex curve from the posterior
to the ventral margin.

The general shape of the palatoquadrate complex is most nearly like that
of _Rhabdoderma elegans_ (Moy-Thomas, 1937:fig. 5). The orientation of
the complex in the living fish was probably oblique, with the processus
ascendens nearly vertical, the quadrate oblique, and the ventral process
of the endopterygoid extending dorsoanteriorly and articulating with the
parasphenoid.

Of the hyoid arch only the ceratohyals (see fig. 5A) are preserved in
several specimens. These are long, curved bones with a posteroventral
process and widened, flaring posterior margin. The medial (?) surface is
concave in one specimen. The lateral (?) surface displays a distinct
ridge on several specimens, arising on the dorsal surface opposite the
posteroventral process and extending diagonally to the anteroventral end
of the anterior limb. The impression of one other specimen appears to
have a central ridge because of greater dorsal thickness and narrowness.
Both surfaces are unornamented.

The urohyal (see fig. 5B) is an unornamented, Y-shaped bone, with the
stem of the Y pointing anteriorly. Orientation with respect to dorsal
and ventral surfaces is uncertain. In one view a faint ridge, also
Y-shaped, occurs on the expanded posterior portion, and the surface is
convex. The anterior process has a convex surface, sloping evenly off to
the lateral margin; the opposite side of the process has a concave
surface. The posterior portion has a slightly depressed area (see fig.
5B) at the junction of the "arms" of the Y.

The five branchial arches are represented by the ceratobranchials,
several of which are preserved on K. U. no. 11431. These are long bones
with anteriorly curving ventral ends. The medial surfaces are partly
covered with minute granular teeth; only the dorsal part is without
teeth. The dorsal articular surface is convex dorsally and rounded.

The mandible (fig. 3), the best specimens of which are K. U. nos. 788
and 11425, is seen only in lateral and ventral views, with only angular,
splenial and dentary visible.

The angular forms the main body of the mandible, and is similar to that
of _Spermatodus_. The dorsal margin of the angular is expanded in the
central region, with some variation. One specimen has an expanded
portion slightly anterior to that of the opposite angular. The articular
surface near the posterior end has not been observed; the posterior end
of the angular slopes off abruptly. The anterior sutures are seen in
only two specimens, K. U. nos. 788, 11425. The dentary meets the angular
in a long oblique suture; the dentary gradually tapers posterodorsally
and ends on the dorsal surface of the angular. The splenial fits into a
posteriorly directed, deep V-shaped notch on the ventral surface. The
lateroventral surface of the angular contains sensory pores of the
mandibular line. The ventral surface extends medially into a narrow
shelf, approximately 1.0 mm. wide, which extends the full length of the
bone; the external surface of this shelf is smooth and slightly concave
dorsally. Ornamentation of the angular consists of tubercles and
longitudinal or oblique striae, occurring mostly on the expanded
portion. The medial surface is not seen. Several broken specimens show
a central canal filled with a rod of calcite; in one of these the
sensory pores are also calcite-filled and appear to be connected to the
rod. Thus the pores originally opened into a central canal.

The dentary is an unornamented bone with the anterior half curving
medially; the greatest height is anterior. This bone in specimen K. U.
no. 11425 bears irregularly spaced, simple, recurved, conical teeth;
nine were counted, but there is space for many others. One other
specimen, no. 11429, seems to have tiny tubercles on the surface. The
dentary meets the splenial dorsally in a straight suture.

The splenial also curves medially, and as stated, meets the dentary in a
straight suture. Ornamentation on this bone was not observed. The
posterior margin is V-shaped and fits the notch in the angular. The
ventral surface bears three or more sensory pores of the mandibular
line.

The gular plates are oval. The medial margin is straight to slightly
curved, the lateral margin curved crescentically, the posterior end is
blunt, and the anterior end somewhat rounded. Ornamentation varies
greatly; some bones show only a few tubercles, whereas others exhibit an
almost concentric pattern of closely spaced striae. Typically there are
some tubercles in the anterior quarter or third of the total length;
these pass into longitudinally oriented striae in the posterior section.
A few have only randomly oriented, widely-spaced striae. The internal
surface is smooth.

The coronoid (K. U. no. 11428) is a triangular bone, with the apex
pointing dorsally. The lateral surface is smooth; no teeth were
observed. Moy-Thomas (1937:292, 293) mentions several tooth-bearing
coronoids in _Rhabdoderma_, but as yet these have not been seen in
_Synaptotylus_.


_Axial skeleton_

Only three specimens (K. U. nos. 786F, 787F, 11450) show parts of the
vertebral column, but isolated neural and haemal arches are numerous.
All are of the coelacanth type, having Y-shaped neural and haemal
arches, without centra. A total count of 38 was obtained, but this was
incomplete; the actual number was probably near 50. Counts of 10 and 16
haemal arches were obtained in two of the specimens. Total height of
neural arches ranges from 7.5 to 12.0 mm., and of haemal arches, from
9.0 to 12.0 mm. The shorter arches are anterior and the height increases
gradually to a maximum in the caudal region. Height of the spines varies
from 4.0 to 9.0 mm., or from twice the height of the arch in the
anterior to three times the height in the caudal region. Total width of
the base, measured in isolated specimens because lateral views in other
specimens prevented measuring width, ranges from 0.7 to 4.2 mm. The
short, broad arches having short spines occur at the anterior end of the
spinal column; the narrower arches having tall spines occur toward the
caudal end. Broken neural and haemal arches show a thin covering of bone
with a central, calcite-filled cavity, which in life may have been
filled with cartilage (Stensiö, 1932:58, fig. 20).

No ossified ribs have been observed, either isolated or in place.

For further description of the axial skeleton, see Hibbard (1933).

[Illustration: FIG. 6. _Synaptotylus newelli_ (Hibbard). Paired fin
girdles. A, pectoral girdle, lateral view, based on K. U. no. 11433, ×
3.5. B, pelvic girdle basal plate, medial (?) view, based on K. U. no.
788, × 8. Anterior is toward the left.]


_Girdles and paired fins_

A nearly complete pectoral girdle on specimen K. U. no. 11433 (see fig.
6A) has only a cleithrum and clavicle. No evidence of an extracleithrum
or supracleithrum has been observed, but the extracleithrum may be fused
to the cleithrum. The two bones form a boot-shaped unit, with the
anteroventral part turned medially to form a horizontal process which
meets the opposite half of the girdle. In lateral view the surface is
unornamented, and convex in the ventral half. The suture between the
cleithrum and clavicle begins on the expanded posterior portion, the
"boot-heel," at a point immediately below the greatest width on the
posterior margin, passes anteriorly, then turns sharply and parallels
the anterior margin. The shape of the cleithrum resembles that in
_Rhabdoderma_ and the internal surface is not ridged (see Moy-Thomas,
1937:fig. 9). The exact orientation in the fish is uncertain, but if the
median extension is really horizontal, then the posterior expansion is
directed caudally. The medial surface is concave, steepest near the
anterior margin, and then slopes outward evenly. In medial view one
specimen (K. U. no. 11426) shows a small, caudally directed projection
of bone, evidently for articulation of the fin-skeleton, at the widest
portion of the cleithrum. Sutures on several specimens were indistinct.
Broken specimens show sutural faces, but many nearly complete specimens
show little or no indication of sutures, without regard to size of the
girdles. The internal structure of the fin was not observed.

Numerous isolated basal plates of the pelvic girdle have revealed
details of structure but no information on the orientation. Presumably
the basal plates of _Synaptotylus_ had essentially the same orientation
as those of other coelacanths (Moy-Thomas, 1937:395). The most complete
basal plate is K. U. no. 788 (see fig. 6B). The three apophyses diverge
anteriorly; the horizontal one is best developed and the dorsal one is
least well developed. A median process (Schaeffer, 1952:49), denticulate
on several specimens, articulates with the corresponding process of the
opposite plate. The expanded part that articulates with the skeleton of
the fin extends caudally. The posterior expanded part is nearly square
in outline, resembling the dorsal, rectangular projection. One side
bears ridges leading to the extremities of the apophyses, and faint
crenulations on the median process. This may be the medial view. The
other view displays a smooth surface, usually without indication of the
ridges seen in the reverse view. These specimens differ somewhat from
the basal plates of _Rhabdoderma_ and appear to be intermediate between
_Rhabdoderma_ and _Coelacanthus_ (Moy-Thomas, 1937:fig. 10A, B). The
apophyses are not free as in _Rhabdoderma_ but webbed with bone almost
to their extremities, as in _Coelacanthus_.

The pelvic fin is seen in only two specimens (K. U. nos. 786F, 788).
That on no. 788 is lobate and has 25 lepidotrichia, jointed for
approximately the distal half, and 2.5 to 13.0 mm. in length. Total
length of the fin is 25.0 mm. There is no trace of the internal skeletal
structure or of the articulation to the basal plate in either specimen.
For a description of the fin on no. 786F, see Hibbard (1933:281).


_Unpaired fins_

A few isolated bones on K. U. no. 788 (fig. 7) are interpreted as basal
plates of the unpaired fins. For additional description of the unpaired
fins on the type, K. U. no. 786F, see Hibbard (1933).

Two of these bones are flat, smooth and oblong, bearing a diagonal ridge
that extends in the form of a projection. Orientation is completely
unknown. These may be basal plates of the anterior dorsal fin. The fin
on no. 786F that Hibbard (1933:281) interpreted as the posterior dorsal
fin is now thought to be the anterior dorsal fin.

[Illustration: FIG. 7. _Synaptotylus newelli_ (Hibbard). Basal plates of
unpaired fins. A, anterior dorsal fin, based on K. U. no. 788, × 10. B,
posterior dorsal fin, based on K. U. no. 788, × 12. C, anal fin, based
on K. U. no. 11450, × 5. Anterior is toward the left.]

One distinctive bone may represent the basal plate of the posterior
dorsal fin. This incomplete specimen shows two projecting curved
processes, bearing low but distinct ridges, which diverge, probably
anteriorly. The central portion is narrow. The two ridges continue onto
the posterior portion. This has been broken off, but shows that the
ridges diverge again. The surface is smooth, except for the ridges. As
before, orientation is uncertain. On no. 786F this fin was interpreted
by Hibbard (1933:281) as the anal fin.

Only part of one basal plate of the anal fin was preserved on K. U. no.
11450. That plate is oblong and has an expanded anterior end. The
narrow, constricted part bears two oblique ridges and a few tubercles.
The posterior part has nearly straight margins (represented by
impressions) and the posterior margin is oblique, sloping
anteroventrally. The flared anterior part has a smooth surface. This
basal plate is more nearly like those of _Coelacanthus_, according to
the descriptions given by Moy-Thomas (1937:399). The basal plate is
associated with seven apparently unjointed, incomplete lepidotrichia.
The anal fin on no. 786F is interpreted as the anterior dorsal fin
(Hibbard, 1933:281).

The caudal fins are preserved on K. U. nos. 786F, 787F, and have a total
of 24 lepidotrichia, 12 above and 12 below. These are jointed for the
distal half or two-thirds, and are up to 16.0 mm. in length. In specimen
no. 787F the supplementary caudal fin has at least seven lepidotrichia,
the longest of which is 11.0 mm. but incomplete. Anterior lepidotrichia
appear unjointed but the posterior ones are jointed for the distal
two-thirds (?) (these are broken off). The supplementary caudal fin is
approximately 1.5 mm. long and 8.0 mm. or more wide. The supplementary
caudal fin on K. U. no. 786F described by Hibbard (1933:281) could not
be observed; this part of the caudal fin is missing.


_Squamation_

In the suite of specimens isolated scales are numerous, but patches of
scales are rare. Only two specimens (K. U. nos. 786F, 787F) are complete
enough for scale counts, but preservation permits only partial counts.
In general the scales resemble those of _Rhabdoderma elegans_
(Newberry).

The scales are oval. The exposed posterior part of each bears
posteriorly converging ridges; the anterior part is widest and shows a
fine fibrillar structure. There are at least six scale-rows on either
side of the lateral line. Lateral line scales show no pores, and except
for slight irregularities in the orientation and length of the posterior
ridges, closely resemble the others. Central ridges on the lateral line
scales are shorter and tend to diverge from the center of the impression
of the canal. The lateral line canal shows only as the impression of a
continuous canal 0.7 mm. in diameter. Preservation is poorest in scales
along the line of the neural and haemal arches; therefore lateral line
scales are rarely preserved. Isolated scales are of two types: those on
which the posterior ridges converge sharply and form the gothic arch
configuration mentioned by Hibbard (1933:282), and those which do not.
Both types of scales can be present on one fish, as shown by specimen
no. 788. This is not apparent on nos. 786F and 787F; all of the scales
on these specimens appear to be much alike. Both Moy-Thomas (1937:385)
and Schaeffer (1952:51, 52) have remarked on the variation of the scales
on different parts of the same fish. Because the number of ridges and
amount of convergence of the ridges is not related to size of the scale,
it is concluded that these characters are not of taxonomic significance.

The strong resemblance of the scales of the Garnett specimens to those
of _Rhabdoderma elegans_ (Newberry) caused Moy-Thomas (1937:399) to add
Hibbard's two species to the synonymy of _R. elegans_. But at that time
only the scales could be adequately described. If the shape of the scale
and the number and pattern of ridges can vary with age, size and shape
of the scale, it follows that assignment of isolated scales to a species
should not be attempted. Assignment to genus should be made only with
caution.

_Discussion._--The relationship of _Synaptotylus_ to other coelacanths
is obscure at present. The knoblike antotic processes on the
basisphenoid are unlike those of any other known coelacanth. The
palatoquadrate complex is shaped like that of _Rhabdoderma elegans_ but
consists of fewer bones, probably because of fusion. The scales resemble
those of _Rhabdoderma_. With regard to general shape of fin girdles, the
pectoral girdle resembles that of _Eusthenopteron_ more than that of
_Rhabdoderma_, but the cleithrum is more nearly like the cleithrum of
_Rhabdoderma_. The pelvic girdle appears to be midway between those of
_Rhabdoderma_ and _Coelacanthus_ in general appearance. Regarding the
basal plates of the remaining fins, those of _Synaptotylus_ appear to
resemble basal plates of both _Rhabdoderma_ and _Coelacanthus_.
Considering the structure of the sphenethmoid region of the braincase,
_Synaptotylus_ is probably more closely related to _Rhabdoderma_ than
to other known coelacanth genera.


COMMENTS ON CLASSIFICATIONS

Classification of Carboniferous coelacanths has been difficult, partly
because the remains are commonly fragmentary, and significant changes in
anatomy did not become apparent in early studies. In general,
coelacanths have been remarkably stable in most characters, and it has
been difficult to divide the group into families. As Schaeffer (1952:56)
pointed out, definition of coelacanth genera and species has previously
been made on non-meristic characters, and the range of variation within
a species has received little attention. For example, Reis (1888:71)
established the genus _Rhabdoderma_, using the strong striation of the
scales, gular plates and posterior mandible as the main characters of
this Carboniferous genus. Moy-Thomas (1937:399-411) referred all
Carboniferous species to _Rhabdoderma_, redescribed the genus and
compared it to _Coelacanthus_, the Permian genus. He cited as specific
characters the ornamentation of the angulars, operculars and gular
plates (Moy-Thomas, 1935:39; 1937:385). Individual variation in some
species has rendered ornamentation a poor criterion. This variation is
apparent in _Synaptotylus newelli_ (Hibbard), some specimens having
little or no ornamentation; others having much more. The number of
ridges and pattern of ridges on the scales also varies. Schaeffer
(1952:56) has found this to be true of _Diplurus_ also. Moy-Thomas
(1935:40; 1937:385) realized that the type of scale is a poor criterion
for specific differentiation. In the search for features useful in
distinguishing genera of coelacanths, Schaeffer and Gregory (1961:3, 7)
found the structure of the basisphenoid to be distinctive in known
genera, and thought it had taxonomic significance at this level. Higher
categories should have as their basis characters that display
evolutionary sequences. A recent classification (Berg, 1940), followed
in this paper, reflects two evolutionary trends in endocranial structure
of coelacanths: reduction of endocranial ossification and loss of the
basipterygoid processes. Because there has been little change in other
structures in coelacanths, Berg's classification is the most useful.
Berg (1940:390) includes _Rhabdoderma_ in the suborder Diplocercidoidei
because of the presence of the basipterygoid processes, and in the
single family, Diplocercidae, but remarks that because of the reduced
amount of endocranial ossification the Carboniferous Diplocercidae
"probably constitute a distinct family." In considering this concept of
classification, the subfamilies Diplocercinae and Rhabdodermatinae of
the family Diplocercidae are proposed above. The subfamily
Rhabdodermatinae includes at present _Rhabdoderma_ and _Synaptotylus_.
The principal characters of the subfamily Rhabdodermatinae, named for
the first known genus, are the retention of the basipterygoid processes
and the reduction of endocranial ossification. Application of this
classification based upon endocranial structure would probably change
existing groupings of species of Carboniferous coelacanths; the entire
complex of Carboniferous genera should be redescribed and redefined. It
will be necessary to consider endocranial structure in any future
classification.

The greater part of the evolution previously mentioned appears to have
been accomplished during the Carboniferous; thereafter coelacanth
structure became stabilized. The trend progressed from Devonian
coelacanths which had two large unpaired bones in the endocranium, and
both antotic and basipterygoid processes on the basisphenoid, to
Carboniferous fishes in which ossification was reduced to a number of
paired and unpaired bones embedded in cartilage, and retaining both
processes, and then post-Carboniferous kinds with reduced ossification
and no basipterygoid processes. The Pennsylvanian was evidently the time
of greatest change for the coelacanths, and they have not changed
significantly since, in spite of the fact that since the Jurassic they
have shifted their environment from shallow, fresh water to moderate
depth in the sea (Schaeffer, 1953:fig. 1). The changes in endocranial
structure appear to be significant, and are perhaps related 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-water fishes,
and that many were from swamp deposits. If Keller is correct, then
members of the genus _Synaptotylus_ may have inhabited the lagoon, the
adjacent sea, or the streams draining into the lagoon. Perhaps these
fishes swam upstream, as modern salmon and tarpon do, although there is
no direct evidence for this. Possibly they lived in the lagoon at times
of scant rainfall and little runoff, when the salinity of lagoon water
approached normal marine values or the fishes may have lived in the
streams, and after death were washed into the lagoon. As numerous
remains of land plants and animals were washed in, perhaps this best
accounts for the presence of the fish in nearly all layers of the
deposits, not only the marine strata.


SUMMARY

A new genus of Pennsylvanian coelacanths, _Synaptotylus_, is described
and a previously named species, _Coelacanthus newelli_ Hibbard, 1933
(_C. arcuatus_ Hibbard, 1933, is a junior synonym), is referred to this
genus. All specimens of _Synaptotylus newelli_ (Hibbard) were collected
from the Rock Lake shale member of the Stanton formation, Lansing group,
Missouri series, six miles northwest of Garnett, Anderson County,
Kansas. _Synaptotylus_ is distinguished from all other coelacanths by a
basisphenoid having large, knoblike antotic processes each connected by
a low ridge to a small basipterygoid process. _Synaptotylus_ is most
closely related to _Rhabdoderma_, but is intermediate between
_Rhabdoderma_ and _Coelacanthus_ in shape of the fin girdles and basal
plates. Two new subfamilies, Diplocercinae and Rhabdodermatinae, of the
family Diplocercidae, are proposed. _Synaptotylus_ and _Rhabdoderma_ are
included in the subfamily Rhabdodermatinae, because both exhibit reduced
ossification in the endocranium and retain basipterygoid processes.

Loss of the basipterygoid processes in post-Carboniferous coelacanths
may reflect the development of a more efficient feeding mechanism, by
allowing the palatoquadrate complex and mandible to swing farther
laterally and expand the oral cavity.

_Synaptotylus newelli_ (Hibbard) may have occupied either the sea or
fresh water; these fishes occur in lagoonal deposits with reptiles and
amphibians, arthropods, marine invertebrates and remains of land plants.

Because scale patterns on _Synaptotylus_ and _Rhabdoderma_ are so nearly
similar and vary with size of the scale and its location on the fish, it
is recommended that isolated scales not be assigned to a species, and to
a genus only with great caution.



LITERATURE CITED


ALDINGER, H.

1931. Ueber karbonische Fische aus Westfälen. Paleont. Zeit.,
13:186-201.


BERG, L. S.

1940. Classification of fishes, both Recent and fossil. Moscow and
Leningrad, 1940 (J. W. Edwards, Ann Arbor, Michigan, 1947, offset
reproduction, pp. 1-345, 197 figs., plus English translation of text,
pp. 346-517, 1947.)


FIEGE, K.

1951. Eine Fisch-Schwimmspur aus dem Culm bei Waldeck. Neues Jahrb.
Geol. and Paläont. Jahrgang 1951:9-31.


HIBBARD, C. W.

1933. Two new species of _Coelacanthus_ from the middle Pennsylvanian of
Anderson County, Kansas. Kansas Univ. Sci. Bull., 21:279-287.


KELLER, G.

1934. Fischreste aus dem oberkarbon des Ruhrgebiets. Gluckauf,
70:913-917.


MOORE, R. C., ELIAS, M. K., and NEWELL, N. D.

1936. A "Permian" flora from the Pennsylvanian rocks of Kansas. Jour.
Geol., 44:1-31.


MOY-THOMAS, J. A.

1935. A synopsis of the coelacanth fishes of the Yorkshire Coal
Measures. Ann. Mag. Nat. Hist., 15 (ser. 10): 37-46.

1937. The Carboniferous coelacanth fishes of Great Britain and Ireland.
Proc. Zool. Soc. London, 107 (B): 383-415.


PEABODY, F. E.

1952. _Petrolacosaurus kansensis_ Lane, a Pennsylvanian reptile from
Kansas. Kansas Univ. Paleont. Contrib., 1:1-41.


REIS, O. M.

1888. Die Coelacanthinen mit besonderen Berücksichtigung der im Weissen
Jura Bayerns verkommenden Arten. Palaeontographica, 35:1-96.


SCHAEFFER, B.

1952. The Triassic coelacanth fish _Diplurus_, with observations on the
evolution of the Coelacanthini. Bull. Amer. Mus. Nat. Hist., 99:art. 2,
29-78.

1953. _Latimeria_ and the history of the coelacanth fishes. New York
Acad. Sci. Trans., (2) 15:170-178.


SCHAEFFER, B., and GREGORY, J. T.

1961. Coelacanth fishes from the continental Triassic of the western
United States. Amer. Mus. Novitates, 2036:1-18.


SCHAEFFER, B., and ROSEN, D. E.

1961. Major adaptive levels in the evolution of the actinopterygian
feeding mechanism. Am. Zool., 1:187-204.


SMITH, J. L. B.

1939. A living coelacanthid fish from South Africa. Trans. Roy. Soc.
South Africa, 28:1-106.

STENSIÖ, E. A.

1921. Triassic fishes from Spitzbergen. Part I. Vienna, Adolf
Holzhausen: 1-307.

1932. Triassic fishes from East Greenland. Meddel. om Grønland,
38:1-305.


TCHERNAVIN, V. V.

1948. On the mechanical working of the head of bony fishes. Proc. Zool.
Soc. London, 118:129-143.


WEHRLI, H.

1931. Die Fauna der Westfälischen Stufen A und B der Bochumer Mulde
zwischen Dortmund und Kamen (Westfälen). Palaeontographica, 74:93-134.


_Transmitted March 29, 1962._





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