A comparative study on some aspects of the structural adaptations to burrowing in the rodents Tachyoryctes Splendens (Rhizomyidae) and Tatera Robusta (Cricetidae)

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University of Dar es Salaam
A comparative study of some aspects of the skeletal and muscular systems and the integument was conducted in the rodents Tachyoryctes splendens, a fossorial chisel-tooth digger and Tatera robusta a necturnal semi-fossorial scratch digger. Features of Arrvicanthis niloticus a non-burrowing rodent were included for comparison. Selected groups of muscles were dissected out, and the weight of an individual muscle was expressed as a percentage of the weight of the group in which it belonged. T. splendens exhibited the following modifications: Large incisors for digging, a heavily build skull with large squamosal bones and well-developed supraoccipital and sagittal crests. These bones provide firm and extensive attachments for the greatly enlarged Temporalis muscle which is involved in digging. The prominent suproocipital crest also provides strong attachment for the Splenius and cleidomastodeus muscles which turn and raise the head. The Coronoid processes of the mandible on which the Remporalis muscles attach, are higher than the condylar processes, thus increasing the mechanical effect of the muscle on the incisor tip. Other modifications in T. splendens include: a long clecranon process on which the Triceps muscle inserts, slightly heavier digit flexors of the palm and pes than in the other two species, in particular the Flexor digitorum profunds superficial head, Flexor digitorum sublimis, Plantaris, Flexores hallucis and digitorum longus and Tibialis posterior muscles. Also the Caudo-femoralis muscle is heavier and wider in T. splendens than in the other two species in this study. These muscles enhance the strenghth available for collecting the loosened soil, transporting it along the tunnel and kicking it out of the burrow. Eccrine glands are absent on the palms and soles of T. splendens which digs with its teeth in relatively moist soil and spends most of its time underground. They are well developed on the palms of T. robusta where their secretion increases static friction between the dry sandy particles and the palms while digging. Thus T. splendens shows considerable structural modification of the skeleton and muscles of the head in particular Temporalis muscles to suit its mode of digging. Apart from the long sharp claws of the forelimbs, T. robusta does not exhibit other obvious modifications of the skeleto-muscular system to its mode of scratch-digging. Many other modifications seen in fossorial mammals such as reduced eyes and pinnae are in contrast enlarge in T. robusta as an adaptation to living in open areas with little cover.
Rodentia, Research, Adaptations (Biology)
Urasa, F. M. (1982) A comparative study on some aspects of the structural adaptations to burrowing in the rodents Tachyoryctes Splendens (Rhizomyidae) and Tatera Robusta (Cricetidae), Masters dissertation, University of Dar es Salaam. Available at