Preventing depredation is vital for survivorship and organisms have evolved a diverse repertoire of adaptations to escape predators. Caudal autotomy and regeneration are striking, coupled adaptations supporting many lizard species survival and evolutionary diversification. We studied the muscles and support structures in original and replacement tails of California alligator lizards (Elgaria multicarinata). We hypothesized regenerated tails exhibit structures that maintain movement capacity. We requisitioned samples of original (n=4) and regenerated (n=4) tails from the California Academy of Science Herpetology Collection and scanned them using a MicroCT scanner. Then, we dipped specimens in a custom-modified iodine solution to render the muscle tissue radio-opaque, and rescanned to visualize muscle tissue (DiceCT). Scans were analyzed and segmented in Amira 3D visualization software. Preliminary results indicate cartilaginous rods replace bony vertebrae and protective osteoderms (bony scales) appear smaller and less dense than originals. Muscles appear less organized and smaller. We anticipate that this species will show similar structure patterns and organization compared to previous studies. Yet muscle sizes should be relatively larger in this species, which uses its tail to move and balance. Results vary due to confounding factors in regeneration phase and environment. This study characterized the secondarily-simplified, regenerated structures by quantifying differences in bone, muscle, and cartilage of regenerated and original tails. Our results enhance our knowledge of appendage regeneration in vertebrates and provide a new model for biomedical and clinical applications including prosthetics and biomimicry. Funded by CSUS RISE R25GM122667.