Metacarpal in the context of "Metatarsal bones"

A finger is a prominent digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities (i.e. hands) such as humans and other primates. Most tetrapods have five digits (pentadactyly), and short digits (i.e. significantly shorter than the metacarpal/metatarsals) are typically referred to as toes, while those that are notably elongated are called fingers. In humans, the fingers are flexibly articulated and opposable, serving as an important organ of tactile sensation and fine movements, which are crucial to the dexterity of the hands and the ability to grasp and manipulate objects.

In terrestrial animals, plantigrade locomotion means walking with the toes and metatarsals flat on the ground. It is one of three forms of locomotion adopted by terrestrial mammals. The other options are digitigrade, walking on the toes and fingers with the heel and wrist permanently raised, and unguligrade, walking on the nail or nails of the toes (the hoof) with the heel/wrist and the digits permanently raised. The leg of a plantigrade mammal includes the bones of the upper leg (femur/humerus) and lower leg (tibia and fibula/radius and ulna). The leg of a digitigrade mammal also includes the metatarsals/metacarpals, the bones that in a human compose the arch of the foot and the palm of the hand. The leg of an unguligrade mammal also includes the phalanges, the finger and toe bones.

Among extinct animals, most early mammals such as pantodonts were plantigrade. A plantigrade foot is the primitive condition for mammals; digitigrade and unguligrade locomotion evolved later. Among archosaurs, the pterosaurs were partially plantigrade and walked on the whole of the hind foot and the fingers of the hand-wing. Out of the plantigrade animals, only a few, such as humans, kangaroos and certain rodents, are obligate bipeds, while most others are functional bipeds.

Pterodactyloidea (/ˌtɛrəˈdækt͡ɬɔɪdɪːə/; derived from the Greek words πτερόν (pterón, for usual ptéryx) "wing", and δάκτυλος (dáktylos) "finger") is one of the two traditional suborders of pterosaurs ("wing lizards"), and contains the most derived members of this group of flying reptiles. They appeared during the middle Jurassic Period, and differ from the basal (though paraphyletic) rhamphorhynchoids by their short tails and long wing metacarpals (hand bones). The most advanced forms also lack teeth, and by the late Cretaceous, all known pterodactyloids were toothless. Many species had well-developed crests on the skull, a form of display taken to extremes in giant-crested forms like Nyctosaurus and Tupandactylus. Pterodactyloids were the last surviving pterosaurs when the order became extinct at the end of the Cretaceous Period, together with the non-avian dinosaurs and most marine reptiles.

"Pterodactyl" is also a common term for pterodactyloid pterosaurs, though it can also be used to refer to Pterodactylus specifically. Well-known examples of pterodactyloids include Pterodactylus, Pteranodon, and Quetzalcoatlus.

Arambourgiania (meaning "Camille Arambourg's") is a genus of pterosaur, an extinct group of flying reptiles, that inhabited Jordan during the Maastrichtian age of the Cretaceous period, around 72 to 66 million years ago. Additional fossil remains from the United States and Morocco have also been found, but their assignment to Arambourgiania is only tentative. The holotype (name-bearing) specimen was discovered in 1943 by a railway worker near Russeifa, Jordan. After examination of the specimen by paleontologist Camille Arambourg, he described it as belonging to a new genus and species in 1959, Titanopteryx philadelphiae. The generic name means "titan wing", as the fossil was initially misidentified as a wing metacarpal (it would be later identified as a cervical (neck) vertebra), while the specific name refers to the ancient name of Amman (the capital of Jordan), Philadelphia. The genus name "Titanopteryx" would later be problematic, as it had already been taken by a fly. Because of this, paleontologist Lev Nessov in 1989 renamed the genus to Arambourgiania, in honor of Arambourg. Since 1943, additional isolated remains including vertebrae, wing bones, and hindlimb bones have been assigned to the genus.

Due to the fragmentary nature of the Arambourgiania fossils, there is little direct information about its anatomy. Its cervical vertebrae are extremely elongated, with the holotype vertebra measuring 77–78 cm (2 ft 6.31 in – 2 ft 6.71 in) in length. Based on the complete neck of its relative Quetzalcoatlus, Arambourgiania had a total neck length of 3 m (9 ft 10 in), longer than those of giraffes. Its vertebrae were also more lightly built and weakly muscled than those of its robust, short-necked relative Hatzegopteryx. Arambourgiania is one of the largest flying animals ever discovered. Initial wingspan estimates ranged from 11 to 13 m (36 to 43 ft), which would have made it the largest known pterosaur. However, given the fragmentary remains, more recent research has suggested wingspans anywhere between 8 to 10 m (26 to 33 ft), which would still place the genus among the largest known flying animals.

The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the proximal phalanges. Being condyloid, they allow the movements of flexion, extension, abduction, adduction and circumduction (see anatomical terms of motion) at the joint.