castoroides, giant beaver, prehistoric animal, extinct species, herbivorous diet, eating aquatic plants, chewing tree bark, gnawing wood, foraging leaves, wetland environment, pond-side vegetation, softwood trees, willow branches, close-up of munching, detailed fur texture, realistic rendering, natural daylight, serene forest landscape, water reflection, dynamic pose, side view, detailed teeth structure, furry body, brown and grey coloration, semi-aquatic setting, tranquil atmosphere, soft focus background.