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

Systematic Framework and Nomenclature

Echols places the new genus within a formal hierarchy: Subclass Crossopterygii, Superorder Coelacanthi, Order Coelacanthiformes, Suborder Diplocercidoidei, Family Diplocercidae, and a new subfamily Rhabdodermatinae. The type genus of this subfamily is Rhabdoderma; the referred genus is Synaptotylus, described as new. The diagnosis of Rhabdodermatinae focuses on cranial ossifications: a partly ossified sphenethmoid region comprising basisphenoid, parasphenoid, and ethmoid ossifications; paired basipterygoid and antotic processes on the basisphenoid; a parasphenoid of normal size fused or closely associated with the basisphenoid; and paired ethmoids in Rhabdoderma (unknown in Synaptotylus). This taxonomic placement is precise and grounded in comparative anatomy.

Fin Anatomy and Comparative Observations

The description of unpaired fins relies on isolated bones from specimen K. U. no. 788. Echols interprets flat, smooth, oblong bones with a diagonal ridge as possible basal plates of the anterior dorsal fin. She notes that a fin Hibbard (1933) identified as the posterior dorsal is now considered the anterior dorsal. A distinctive incomplete bone with two projecting curved processes and low ridges is tentatively assigned to the posterior dorsal fin. The anal fin basal plate, preserved only in part on K. U. no. 11450, is oblong with an expanded anterior end, constricted middle bearing two oblique ridges and tubercles, and a posterior part with nearly straight margins. Echols compares this plate to those of Coelacanthus per Moy-Thomas (1937). The caudal fins, preserved on two specimens, show 24 lepidotrichia (12 above, 12 below) jointed for the distal half or two-thirds. The supplementary caudal fin on no. 787F has at least seven lepidotrichia, the longest 11.0 mm but incomplete. These details illustrate the fragmentary nature of the material and the careful inference required.

Squamation and Scale Morphology

Scales are numerous but patches are rare; only two specimens (K. U. nos. 786F, 787F) permit partial scale counts. Echols describes the scales as oval, with the exposed posterior part bearing posteriorly converging ridges and the anterior part widest with a fine fibrillar structure. She states they generally resemble those of Rhabdoderma elegans (Newberry). The description is concise and comparative, avoiding overinterpretation given the limited preservation.

Reading the Evidence: Fragmentary Fossils and Careful Inference

Throughout the monograph, Echols repeatedly qualifies her observations with phrases such as “orientation is completely unknown,” “interpreted as,” and “could not be observed.” For example, the basal plates of unpaired fins are identified tentatively, and the orientation of several bones remains uncertain. The pelvic fin is seen in only two specimens, with no trace of internal skeletal structure or articulation. This cautious language signals that the reader is encountering a work-in-progress of paleontological description, where each bone must be weighed against comparative material. The text is dense with specimen numbers (K. U. nos. 786F, 787F, 788, 11450) and references to earlier work by Hibbard (1933) and Moy-Thomas (1937). A first-time reader should pay attention to these citations and the conditional verbs; they reveal the boundaries of what can be known from the fossils.

Echols’s monograph is a technical description aimed at specialists, but its structure rewards a patient reader. The systematic section provides the taxonomic skeleton; the anatomical descriptions fill in the bones. The frequent comparisons to Rhabdoderma and Coelacanthus situate Synaptotylus within a broader evolutionary context. For those new to paleontological writing, noting how Echols handles uncertainty—by stating what is missing, broken, or ambiguous—offers a model of scientific caution. The work stands as a careful contribution to the knowledge of Pennsylvanian coelacanths from Kansas.

Fingering the plate of Synaptotylus newelli, those quiet scales pressed into shale, I felt the same patient awe that must have gripped Echols—and it drifted me back to a childhood copy of The Sea and Its Living Wonders A Popular Account of the Marvels of the Deep and of the Progress of Martime Discovery from the Earliest Ages to the Present Time — A Closer Reading, where every strange fin was simply wonder, unburdened by taxonomy.