Faculty Advisor(s)

Mateusz Wosik



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Bone elements can reveal varying characteristics for each rodent, so it is best to analyze overlapping elements between and among taxa when drawing comparative conclusions.

Fossorial animals present robust skeletons, strong scapular girdles, short fore- and hind limbs, and prominent attachment sites for muscles. In an animal that is primarily cursorial it is expected to see a slimmer forelimb because the need for strong limbs to deal with biochemical strains is not present.

Using a sample of Marmota monax (groundhog) and Tamias striatus (chipmunk), two common taxa found in northeastern Pennsylvania, we can examine the locomotory modes of these closely related Sciurid rodents.

We found that the groundhog has more robust features while the chipmunk has more gracile elements. In the groundhog we found the epiphysis to be more porous indicating its juvenile nature. The groundhog also showed larger trochanters on both its femurs compared to the chipmunk. The chipmunk has its tibia and fibulas fused together while the groundhogs are two separate bones. The inferior epiphysis of the groundhog appears more robust and has a defined olecranon fossa.

Our results demonstrate how chipmunks use a cursorial pattern and how groundhogs use a fossorial pattern. Robust limbs allow for the animal to deal with biomechanical strains such as compression and bending. A robust limb is not as flexible as a gracile one. In addition to being gracile, the limbs are also elongated allowing for longer strides.

Future osteohistological research will be conducted to further compare biomechanical characteristics using bone microstructure.

Publication Date


Document Type





Sciurid, osteology, locomotory


Comparative and Evolutionary Physiology | Life Sciences | Other Animal Sciences

Osteological Identification and Morphological Comparison of Extant Sciurids