Claw in the context of Reptiles

Archaeopteryx (/ˌɑːrkiːˈɒptərɪks/ ; lit. 'ancient wing'), sometimes referred to by its German name, "Urvogel " (lit. 'Primeval Bird') is a genus of bird-like dinosaurs. The genus name derives from the Ancient Greek ἀρχαῖος (archaîos), meaning 'ancient', and πτέρυξ (ptérux), meaning 'feather, wing'. Between the late 19th century and the early 21st century, Archaeopteryx was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including Anchiornis, Xiaotingia, Aurornis, and Baminornis.

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of Archaeopteryx could grow to about 50 cm (20 in) in length. Despite their small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton.

The cat (Felis catus), also referred to as the domestic cat, is a small carnivorous mammal. It is an obligate carnivore, requiring a predominantly meat-based diet. Its retractable claws are adapted to killing small prey species such as mice and rats. It has a strong, flexible body, quick reflexes, and sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator.Cat communication includes meowing, purring, trilling, hissing, growling, grunting, and body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It secretes and perceives pheromones. Cat intelligence is evident in its ability to adapt, learn through observation, and solve problems. Female domestic cats can have kittens from spring to late autumn in temperate zones and throughout the year in equatorial regions, with litter sizes often ranging from two to five kittens.

The domestic cat is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the domestication of the cat started in the Near East around 7500 BCE. Today, the domestic cat occurs across the globe and is valued by humans for companionship and its ability to kill vermin. It is commonly kept as a pet, working cat, and pedigreed cat shown at cat fancy events. Out of the estimated 600 million domestic cats worldwide, 400 million reside in Asia, including 58 million in China. The United States leads in cat ownership with 73.8 million cats, followed by the United Kingdom with approximately 10.9 million cats. It also ranges freely as a feral cat, avoiding human contact. Pet abandonment contributes to increasing of the global feral cat population, which has driven the decline of bird, mammal, and reptile species. Population control includes spaying and neutering.

Apatosaurus (/əˌpætəˈsɔːrəs/; meaning "deceptive lizard") is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, Apatosaurus ajax, in 1877, and a second species, Apatosaurus louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t (16.1–22.0 long tons; 18.1–24.7 short tons). A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t (32 long tons; 36 short tons).

The cervical vertebrae of Apatosaurus are less elongated and more heavily constructed than those of Diplodocus, a diplodocid like Apatosaurus, and the bones of the leg are much stockier despite being longer, implying that Apatosaurus was a more robust animal. The tail was held above the ground during normal locomotion. Apatosaurus had a single claw on each forelimb and three on each hindlimb. The Apatosaurus skull, long thought to be similar to Camarasaurus, is much more similar to that of Diplodocus. Apatosaurus was a generalized browser that likely held its head elevated. To lighten its vertebrae, Apatosaurus had air sacs that made the bones internally full of holes. Like that of other diplodocids, its tail may have been used as a whip to create loud noises, or, as more recently suggested, as a sensory organ.

Owls are birds from the order Strigiformes (/ˈstrɪdʒəfɔːrmiːz/), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers adapted for silent flight. Exceptions include the diurnal northern hawk-owl and the gregarious burrowing owl.

Owls are divided into two families: the true (or typical) owl family, Strigidae, and the barn owl and bay owl family, Tytonidae. Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish. They are found in all regions of the Earth except the polar ice caps and some remote islands.

Keratin (/ˈkɛrətɪn/) is one of a family of structural fibrous proteins also known as scleroproteins. It is the key structural material making up scales, hair, nails, feathers, horns, claws, hooves, and the outer layer of skin in tetrapod vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biological matter known to approximate the toughness of keratinized tissue is chitin.Keratin comes in two types: the primitive, softer forms found in all vertebrates and the harder, derived forms found only among sauropsids (reptiles and birds).

Abscission (from Latin ab- 'away' and scindere 'to cut') is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. In cell biology, abscission refers to the separation of two daughter cells at the completion of cytokinesis.

Plesiadapiformes ("Adapid-like" or "near Adapiformes") is an extinct basal pan-primates group, as sister to the rest of the pan-primates. The pan-primates together with the Dermoptera form the Primatomorpha. Purgatorius may not be a primate as an extinct sister to the rest of the Dermoptera or a separate, more basal stem pan-primate branch. Even with Purgatorius removed, the crown primates may even have emerged in this group.

Plesiadapiformes first appear in the fossil record between 65 and 55 million years ago, although many were extinct by the beginning of the Eocene. They may be the earliest known mammals to have finger nails in place of claws. In 1990, K.C. Beard attempted to link the Plesiadapiformes with the order Dermoptera. They proposed that paromomyid Phenacolemur had digital proportions of the fossil indicated gliding habits similar to that of colugos.

A paw is the soft foot-like part of a mammal, generally a quadruped, that has claws. To paw is for an animal to use their paws, usually gently or for digging, or for a human to use their hands in the manner of an animal's paw.

Alpha-keratin, or α-keratin, is a type of keratin found in mammalian vertebrates. This protein is the primary component in hairs, horns, claws, nails and the epidermis layer of the skin. α-keratin is a fibrous structural protein, meaning it is made up of amino acids that form a repeating secondary structure. The secondary structure of α-keratin is very similar to that of a traditional protein α-helix and forms a coiled coil. Due to its tightly wound structure, it can function as one of the strongest biological materials and has various functions in mammals, from predatory claws to hair for warmth. α-keratin is synthesized through protein biosynthesis, utilizing transcription and translation, but as the cell matures and is full of α-keratin, it dies, creating a strong non-vascular unit of keratinized tissue.

The integumentary system is the set of organs forming the outermost layer of an animal's body, comprising the skin, hair, scales, feathers, hooves, claws, and nails. It acts as a protective physical barrier between the external environment and the internal environment. Additionally, it maintains water balance, protects the deeper tissues, excretes waste, regulates body temperature, and contains the sensory receptors that detect pain, sensation, pressure, and temperature.

The skin (integument) is a composite organ, made up of at least two major layers of tissue: the outermost epidermis and the inner dermis, which are separated by a basement membrane (comprising basal lamina and reticular lamina). The epidermis comprises five layers: the stratum corneum, stratum granulosum, stratum spinosum and stratum basale. Where the skin is thicker, such as in the palms and soles, there is an extra layer of skin between the stratum corneum and the stratum granulosum known as the stratum lucidum. The dermis comprises two sections, the papillary and reticular layers, and contains connective tissues, blood vessels, glands, follicles, hair roots, sensory nerve endings, and muscular tissue. Between the integument and the deep body musculature there is a transitional subcutaneous zone, the hypodermis.

A chela (/ˈkiːlə/) – also called a claw, nipper, or pincer – is a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek χηλή, through Neo-Latin chela. The plural form is chelae. Legs bearing a chela are called chelipeds. Another name is claw because most chelae are curved and have a sharp point like a claw.

Chelae can be present at the tips of arthropod legs as well as their pedipalps. In some pseudoscorpions, the chelate pedipalps can be venomous. Chelae can be functionally overlapping with chelicerae, which specifically refers to appendages used as mouthparts in Chelicerata. In spiders those usually contain venom glands, but in other chelicerate allies the chelicerae can be chelate without venom glands.

Armor or armour in animals is a rigid cuticle or exoskeleton that provides exterior protection against attack by predators, formed as part of the body (rather than the behavioural utilization of external objects for protection) usually through the thickening and hardening of superficial tissues, outgrowths or skin secretions. It is often found in prey species that are too slow or clumsy to outrun predators, or those that would stand their ground and fight, thus needing to protect vital organs against claw, talon or bite injuries.

Metanephrops is a genus of lobsters, commonly known as scampi. Important species for fishery include Metanephrops australiensis (Australian scampi) and Metanephrops challengeri (New Zealand scampi). It differs from other lobsters such as Homarus and Nephrops norvegicus in that its two main claws are of equal size, rather than being differentiated into a crusher and a pincher. There are 18 extant species recognised in the genus:

Brachyura (from Ancient Greek βραχύς (brakhús), meaning "short", and οὐρά (ourá), meaning "tail"), is an infraorder of decapod crustaceans comprising the true crabs. They typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. Their exoskeleton is often thickened and hard. They generally have five pairs of legs, and they have "pincers" or "claws" on the ends of the frontmost pair, scientifically termed the chelae. They are present in all the world's oceans, in freshwater, and on land, often hiding themselves in small crevices or burrowing into sediment. True crabs are omnivores, feeding on a variety of food, including a significant proportion of algae, as well as detritus and other invertebrates. True crabs are widely consumed by humans as food, with over 1.5 million tonnes caught annually.

True crabs first appeared in the fossil record during the Jurassic period, around 200 million years ago, achieving great diversity by the Cretaceous period; around 7,000 extant species in 96 families are known. The true crabs are the largest of the crab decapod groups with carcinised body forms. Smaller groups include the porcelain crabs, king crabs, and hairy stone crabs which have independently evolved similar forms and lifestyles.

A nail is a protective plate characteristically found at the tip of the digits (fingers and toes) of almost all primates (except for marmosets), corresponding to the claws in other tetrapod animals. Fingernails and toenails are made of a tough rigid protein called alpha-keratin, a polymer also found in the claws, hooves, and horns of vertebrates.