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There are 126 bones in the human appendicular skeleton, includes the skeletal elements within the shoulder and pelvic girdles, upper and lower limbs, and hands and feet. [1] These bones have shared ancestry (are homologous) to those in the forelimbs and hindlimbs of all other tetrapods, which are in turn homologous to the pectoral and pelvic ...
The pectoral girdles are to the upper limbs as the pelvic girdle is to the lower limbs; the girdles are the part of the appendicular skeleton that anchor the appendages to the axial skeleton. In humans, the only true anatomical joints between the shoulder girdle and the axial skeleton are the sternoclavicular joints on each side.
The pectoral and pelvic fins are paired, whereas the dorsal, anal and caudal fins are unpaired and situated along the midline of the body. For every type of fin, there are a number of fish species in which this particular fin has been lost during evolution (e.g. pelvic fins in † Bobasatrania , caudal fin in ocean sunfish ).
Limbs are attached to the torso via girdles, either the pectoral girdle for the forelimbs, or the pelvic girdle for the hindlimbs.In terrestrial tetrapods, the pectoral girdles are more mobile, floating over the rib cage connected only via the clavicles (to the sternum) and numerous muscles; while the pelvic girdles are typically fused together anteriorly via a fibrocartilaginous joint and ...
The bones to which the pectoral fin is attached. peduncle Usually referred to as the caudal peduncle, the region of the body between the end of the anal fin and the base of the caudal fin. pelagic Living on or in the open seas. pelvic girdle The bones to which the ventral fins are attached. pelvic fins Paired fins behind or below the pectoral fins.
The pectoral and pelvic fins of many reef fish, such as butterflyfish, damselfish and angelfish, have evolved so they can act as brakes and allow complex maneuvers. [39] Many reef fish, such as butterflyfish , damselfish and angelfish , have evolved bodies which are deep and laterally compressed like a pancake, and will fit into fissures in rocks.
It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish. In animals with two flippers, such as whales, the flipper refers solely to the forelimbs. In animals with four flippers, such as pinnipeds and sea turtles, one may distinguish fore-and hind-flippers, or pectoral flippers and pelvic flippers. [2] [3]
Pelvic bone fossils from Tiktaalik shows, if representative for early tetrapods in general, that hind appendages and pelvic-propelled locomotion originated in water before terrestrial adaptations. [41] Another indication that feet and other tetrapod traits evolved while the animals were still aquatic is how they were feeding.