i think
shark
The wings.
Feathers are a structure that are common to all species of bird. Most feathers are very similar in structure, although they vary depending on how and where the bird lives.
A forelimb is an anterior (front-most) limb (arm, leg, or similar appendage) on an animals's body.
There are many organism with a forelimb with the most primitive trait. These animals include certain species of monkey animals.
Any bird is technically a dinosaur and Terror birds were the most similar to the actual beast of the Mesazoic. The body and stance of all species of terror bird were extremely similar to the body structure of therapod dinosaurs. Terror Birds were also very fast runners just like modern Ostriches and just like their Dromaeosaur ancestors.
Vasopressin is the hormone most similar to oxytocin in chemical structure. Both hormones are nonapeptides, containing nine amino acids, and differ by only two amino acids in their structure.
Uranus
the walls of lymphatic vessels are similar to those of veins
The thigh muscle
A primate, as both primates and rodents are mammals.
The bird's wing is most similar to a human arm because both structures have a similar skeletal layout with long bones (humerus, radius, and ulna in humans; humerus, radius, and ulna in birds) supporting the limb and connected by joints. The bird's wing, however, is modified with feathers for flight.