Pseudothumb
Pseudothumb, often called a false thumb, is a morphological adaptation in some mammals in which the radial sesamoid bone at the wrist enlarges to form a projection that functions as an opposable digit. It is not a true thumb, which involves a metacarpal and proximal phalanx; the pseudothumb is a modified bone that, together with surrounding soft tissues, allows enhanced grasping.
The best-known examples are in the giant panda (Ailuropoda melanoleuca) and the aye-aye (Daubentonia madagascariensis). In
Functionally, the pseudothumb increases the animal’s ability to manipulate objects and feed efficiently. It acts as
In scientific literature, the term pseudothumb is used to describe this type of adaptation, particularly in