Two New Pocket Gophers from Wyoming and Colorado

In Short

This monograph is a formal taxonomic study conducted by biologists at the University of Kansas in the early 1950s. It focuses on the northern pocket gopher (Thomomys talpoides) and presents the evidence required to formally name two new subspecies, T. t. rostralis and T. t. attenuatus. By synthesizing years of field collections, anatomical measurements, and comparative analysis of skull structures, the authors delineate the geographic boundaries and physical characteristics of these populations. It serves as a precise, archival record of biological classification, demonstrating the meticulous labor behind establishing the diversity of North American mammals.

The Story

The narrative begins in the academic year of 1947–48, when researchers initiate a systematic review of the northern pocket gopher's geographic variations across Wyoming. The work is not a singular event but a multi-year project involving the accumulation of specimens housed at the University of Kansas Museum of Natural History. The authors, E. Raymond Hall and H. Gordon Montague, recognize that a definitive classification requires more than just local data; it necessitates the integration of findings from neighboring Colorado.

The core of the study involves a rigorous comparison of physical traits. The researchers analyze hundreds of individual gophers, focusing on the subtle differences in skeletal structure—specifically the shape of the skull, the length of the rostrum, and the orientation of the zygomatic arches. As they process the specimens, the researchers identify two distinct populations that do not fit into existing classifications. One group, which they name Thomomys talpoides rostralis, is characterized by a longer rostrum and specific cranial features that distinguish it from the neighboring T. t. fossor and T. t. macrotis. The other, Thomomys talpoides attenuatus, is identified by its smaller overall size and a notably slenderer, smoother skull compared to surrounding subspecies.

The arc of the study involves the resolution of previous taxonomic uncertainties. The authors describe how early, localized findings were complicated by variations in color and size across the Medicine Bow Range and the North Platte River Valley. By examining a vast array of samples, they discover a "cline"—a gradual change in color intensity from the eastern plains toward the Sierra Madre mountains. This insight allows them to dismiss the idea that the Medicine Bow population is a separate subspecies, instead folding it into the broader range of rostralis.

The conclusion of the study is a formal, scientific declaration. The authors provide the precise type localities for the new subspecies—rostralis near Laramie, Wyoming, and attenuatus west of Horse Creek, Wyoming. They present an extensive list of specimens examined, grounding their names in the physical evidence of 168 individual gophers. The work ends with a detailed data table that serves as a permanent reference for future biologists, standardizing the measurements of these animals and establishing a clearer framework for understanding the biological diversity of the Rocky Mountain region.

How It Unfolds

The investigative premise The researchers outline the necessity of their study, explaining how initial 1947 collections in Wyoming were intentionally held back to allow for a broader comparison with Colorado specimens. They establish the goal of reconciling regional variations into a consistent taxonomic framework.

The diagnostic process The authors introduce the two new subspecies by detailing their physical "diagnosis." They compare these animals against existing subspecies, using specific anatomical markers like the shape of the interpterygoid space and the inflation of the tympanic bullae.

The resolution of environmental patterns The narrative examines the "remarks" section, where the authors identify a cline of color variation. They explain how environmental geography influences the physical appearance of the gophers, leading them to reassign large areas of Colorado into the range of the newly named rostralis.

The final classification The study concludes by providing a comprehensive list of specimens examined from various counties. It presents a quantitative table, finalizing the measurements that distinguish these two subspecies from all known relatives.

The People

The central figures are the biologists E. Raymond Hall and H. Gordon Montague. They function as the primary investigators, driven by a desire to bring order to the taxonomic chaos surrounding the northern pocket gopher. Their work is characterized by a commitment to empirical evidence; they are willing to delay publication for years to ensure that their conclusions are supported by a large enough sample size.

The "characters" they interact with are the specimens themselves. The individuals who collected these animals—such as C. Howard Westman and Henry W. Setzer—serve as the silent agents of the study, providing the raw data that allows Hall and Montague to form their arguments. The gophers are, in a sense, the subjects of a grand categorization; they are scrutinized, measured, and assigned names based on their physical manifestations. The authors treat every specimen with equal gravity, whether it comes from a high mountain peak or a valley floor, viewing each as a piece of a larger puzzle. The researchers emerge not as explorers of uncharted lands, but as explorers of biological variation, shifting their understanding of these animals based on the objective reality of the skull and skin measurements before them.

In Its Own Voice

"Acquisition of more material from still farther west (Sierra Madre) in Wyoming and the examination of material in the United States Biological Surveys Collection from Colorado discloses that there is a cline of increasing intensity of color from the geographic range of T. t. cheyennensis at Pine Bluffs, Wyoming, westward to the eastern side of the Sierra Madre at a locality three miles east and five miles north of Savery, Wyoming."

The authors describe the process of mapping biological change across a geographic range.

"A further deterrent to setting apart the animals of the Medicine Bow Mountains as a separate subspecies is the large size of males from the North Platte River Valley southeast of Saratoga."

The authors explain how they corrected an initial, premature hypothesis by using new, intermediate data.

What It's Really About

This work is fundamentally about the scientific process of classification and the inherent fluidity of nature. It explores the tension between naming a species—a rigid, human-made category—and the reality of animals that exist in a state of constant, gradual variation. The underlying question is how to draw a meaningful boundary in a landscape where populations blend into one another. By focusing on cranial measurements and skeletal geometry, the authors attempt to provide an objective, stable foundation for understanding how geography shapes life. It is an argument for the necessity of rigorous, evidence-based taxonomy, suggesting that the "truth" of a species is found not in a single individual, but in the statistical analysis of a vast population.

Why Read It Today

Readers interested in the history of natural science or the specific biodiversity of the Rocky Mountains will find this an essential, if specialized, read. It provides a rare, unvarnished look at the work of mid-century field biology—a time when classification relied on physical handling of specimens and manual data tabulation. There is a quiet, rhythmic beauty in the precision of the descriptions; the reader is invited to look as closely at the shape of a gopher's skull as the scientists did in 1951.

However, the reader should be prepared for a highly technical experience. This is not a narrative book in the traditional sense; it is a scholarly report filled with Latin terminology and detailed measurement tables. It is dense, rhythmic, and uncompromising in its focus. One of the joys of reading it today is the sense of stability it provides; while the taxonomy of these animals may have shifted in the decades since, the record itself remains a fixed, reliable anchor. It is a work for those who appreciate the patient, often invisible, labor of categorizing the natural world. It reminds us that our understanding of nature is built upon the incremental, meticulous work of individuals who, one specimen at a time, define the living landscape.