A Descriptive Analysis of The Musculature And Osseous Systems of The Kangaroo Rat, Dipodomys Ordii
Authors:   , Mathis Virgil 
Published: February 2023

The kangaroo rats constitute the only genus, Dipodomys, of the subfamily Heteromyinae, now extant . There is fossil evidence of two other genera which are now extinct. The kangaroo rat, Dipodomys ordii richardsoni, is one of the common rodents of western Kansas . According to Hibbard (3, p. 76), \Its range extends northeastward along the Kansas river into Riley County.\ These animals are easily distinguished from other rodents by their long tail, long hind legs and feet, small hands, fur lined external cheek pouches, and their saltating method of locomotion. These rodents are seldom seen by the casual observer, being strictly nocturnal and very timid. A good way to observe their activity is to drive by automobile through a pasture at night. It is not uncommon to see numbers of them bounding along in front of the headlights. Not often are the kangaroo rats considered of much economic importance. They build their shallow burrows in gravelly or more frequently sandy soil. They seem to thrive best around old sand pits, sand dunes or valley borders . They are chiefly inhabitants of desert country, but may thrive in out of the way places in semi-arid regions. Apparently almost all kinds of seeds are utilized as food by these animals . Woodhouse has reported finding in their cheek pouches great- numbers of seeds of wild sunflowers (Helianthus and Ximenesia) and also hard beans of a legume (Parosela). Goldman has observed them gathering seeds of the common mesquite (Prosopis glandulosa). In an examination of the pockets Goldman found in various specimens the seeds of the rag bush (Gaertheris acanthicarpa), ripening seeds of the desert willow (Chilopsis linearis), seeds of tumble weed (Atriplex expansa), 0 capsules of the common purslane (Portulaca oleracea), seeds of cr~sote bush (Covillea tridentata), arrl others. From the appearance of their burrow entrances, they must be rather neat housekeepers\. These openings are often strewn with seed husks which have been thrown out from their dens. This writer found the seed husks of the sandbur (Cenchrus paudflorus), and the seed pods of the Rocky Mountain bee plant (Cleome serrulata) literally forming a carpet of refuse at some of the burrow entrances. One other highly important adaptation of these animals to their environment is their ability to live indefinitely without water. The animal is capable of utilizing enough metabolic water to carry on all life processes. Pearse has stated that, \Physiology is the keystone of ecology\; Howell has mentioned that, \The internal anatomy of all but a few mammals has been woefully neglected\; and Hall believes “… that taxonomic characters of considerable value will be found 'in the musculature when more forms have been studied. These needs form the stimulus for this research. This being an anatomical problem, and not an ecological one, the remainder of the paper shall deal with the animal solely from the point of view of anatomy. The specimens collected for this study were caught in live traps baited with oatmeal. Eight specimens were caught in an old abandoned sand pit twelve miles south of Hays, Kansas. Six of these, four males and two females, were measured for total length, length of tail, and length of pes, and preserved in a ten per cent solution of formalin for study. These six specimens were dissected. No muscles requiring microscopy were considered. Not in every case were all the muscles compared but wherever variation was found or any degree of doubt persisted it was checked in all six specimens. An attempt is made to describe the muscular system with extreme thoroughness. The ossesous system is not nearly as intricate and is treated in much less detail.