The well-preserved forelimbs are the most distinctive parts of
A. simonsi. A broad scapula and a ball-and-socket shoulder joint is characteristic of cetaceans, but
Ancalecetus lacks both. The interior surface of the narrow scapula is not broadly curved as in most cetaceans, but tightly curved. The roughened vertebral border suggests the presence of a cartilaginous extension that extends the surface of the scapula like in modern cetaceans. Compared to other cetaceans, the
infraspinous fossa is smaller, the caudal border is less curved and not oriented posteriorly. The
glenoid cavity is very shallow and directed posteriorly, rather than ventrally like in other cetaceans. Likewise, the oddly folded
acromion is pointing ventrally and posteriorly, and not anteriorly as in other cetaceans. Unlike in other basilosaurids, the humerus of
Ancalecetus is flattened and has a relatively small head. The distal end has flat, textured surfaces for the articulation of the radius and ulna; these bones are fused on the left limb and tightly fitting and the right side, and neither permitted motion at the elbow joint. ==Dentition==