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_ Stensioe, _Nesides_ Stensioe 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.

Table of contents (by pages)

• 1: A New Genus of Pennsylvania Fish (Crossoperygii, C
• 2: Curving to fit lateral margin of intertemporals
• 3: 9939 in posterodorsal and ventral views
• 4: Evidently many of the coelacanths
• 5: As seen on the intertemporal of R
• 6: Part of one squamosal is preserved
• 7: Of the hyoid arch only the ceratohyals see fig
• 8: The dentary meets the splenial dorsally in a straight suture
• 9: The three apophyses diverge anteriorly
• 10: Unpaired fins A few isolated bones on K
• 11: Coelacanths have been remarkably stable in most characters
• 12: Thereafter coelacanth structure became stabilized
• 13: SUMMARYA new genus of Pennsylvanian coelacanths
• 14: The Triassic coelacanth fish Diplurus