It is known also as the base or root of the tail, and corresponds to the human sacrococcygeal symphysis.
Similarly, the silhouette of the tailfan is a characteristic widely used for purposes of identification, particularly in the field.
In equine anatomy, the croup refers specifically to the topline of the horse's hindquarters and surrounding musculature, beginning at the hip, extending proximate to the sacral vertebrae and stopping at the dock of the tail (where the coccygeal vertebrae begin).
Its meaning may be extended to either the entire tail minus the skirt (i.e., synonymous with tailbone)[1][5] or the tailhead only.
[6] In other equidae, it encompasses most of the tailbone, as most of that portion of the tail does not have long hairs.