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In typical early tetrapod posture, the upper arm and upper leg extended nearly straight horizontal from its body, and the forearm and the lower leg extended downward from the upper segment at a near right angle. The body weight was not centered over the limbs, but was rather transferred 90 degrees outward and down through the lower limbs, which ...
A forelimb or front limb is one of the paired articulated appendages attached on the cranial end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. In bipedal animals with an upright posture (e.g. humans and some other primates), the term upper limb is often used.
This list draws examples from three broad groups of animals: tetrapods (with 0 to 2 leg pairs, [7] [8] providing three examples), velvet worms (with 13 to 43 leg pairs, [9] providing ten examples), and arthropods (with 3 to 653 leg pairs, [10] [1] providing all the other examples). Four classes of arthropods each provide multiple examples ...
The distal half of the limb proper has two long bones, together termed the zeugopodium (plural: zeugopodia). These may be radius and ulna of the forearm, or the tibia and fibula of the shin. The distalmost portion or extremity of the limb, i.e. the hand or foot, is known as the autopodium (plural: autopodia).
The shoulder girdle [5] or pectoral girdle, [6] composed of the clavicle and the scapula, connects the upper limb to the axial skeleton through the sternoclavicular joint (the only joint in the upper limb that directly articulates with the trunk), a ball and socket joint supported by the subclavius muscle which acts as a dynamic ligament. While ...
Though stem-tetrapods originated in the preceding Devonian, it was in the earliest Carboniferous that the first crown tetrapods appeared, with full scaleless skin and five digits. During this time, amphibians (including many extinct groups unrelated to modern forms, referred to as "basal tetrapods") were the predominant tetrapods, and included ...
Polydactyly in early tetrapod aquatic animals, such as in Acanthostega gunnari (Jarvik 1952), one of an increasing number of genera of stem-tetrapods known from the Upper Devonian, which are providing insights into the appearance of tetrapods and the origin of limbs with digits. It also occurs secondarily in some later tetrapods, such as ...
Tetrapodomorpha (also known as Choanata [3]) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish.