"Egg binding Egg binding occurs in animals, such as reptiles or birds, when an egg takes longer than usual to pass out of the reproductive tract. In birds, egg binding may be caused by obesity, nutritional imbalances such as calcium deficiency, environmental stress such as temperature changes, or malformed eggs. The egg may be stuck near the cloaca, or further inside. Egg binding is a reasonably common, and potentially serious condition that can lead to infection or damage to internal tissue. The bound egg may be gently massaged out; failing this it may become necessary to break the egg ""in"
"the four familiar classes of amphibians, reptiles, birds, and mammals. In this system, reptiles are characterized by traits such as laying membranous or shelled eggs, having skin covered in scales or scutes, and having a 'cold-blooded' metabolism. However, the ancestors of mammals and birds also had these traits and so birds and mammals can be said to ""have evolved from reptiles"", making the reptiles, when defined by these traits, a grade rather than a clade. In microbiology, taxa that are thus seen as excluded from their evolutionary grade parent group are called taxa in disguise. Paraphyletic taxa will often, but"
"Bird Birds, also known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the bee hummingbird to the ostrich. They rank as the world's most numerically-successful class of tetrapods, with approximately ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have which are more or less developed depending on the species; the only known groups without wings are the extinct moa"
"the Hymenoptera, Diptera, and Coleoptera. Lepidopteran species are characterized by more than three derived features. The most apparent is the presence of scales that cover the bodies, wings, and a proboscis. The scales are modified, flattened ""hairs"", and give butterflies and moths their wide variety of colors and patterns. Almost all species have some form of membranous wings, except for a few that have reduced wings or are wingless. Mating and the laying of eggs are carried out by adults, normally near or on host plants for the larvae. Like most other insects, butterflies and moths are holometabolous, meaning they"
"are composed of the same keratin as beaks, claws, and spurs. They are found mainly on the toes and metatarsus, but may be found further up on the ankle in some birds. Most bird scales do not overlap significantly, except in the cases of kingfishers and woodpeckers. The scales of birds are thought to be homologous to those of reptiles and mammals. Most birds can fly, which distinguishes them from almost all other vertebrate classes. Flight is the primary means of locomotion for most bird species and is used for searching for food and for escaping from predators. Birds have"
"which traits are often sorted among amphibians, reptiles, mammals, avafauna, arthropods and lower life forms. For many amphibians, an annual breeding cycle applies, typically regulated by ambient temperature, precipitation, availability of surface water and food supply. This breeding season is accentuated in temperate regions, where prolonged aestivation or hibernation renders many amphibian species inactive for prolonged periods. Breeding habitats are typically ponds and streams. Annual breeding cycles sometimes apply to mammals, with regulating environmental effects including seasonal temperature variation and food availability. Migration patterns of a mammal may sometimes govern breeding times. Mammal breeding in the wild sometimes involves the"
"when one species lays its eggs in the nest of another. In some cases, the host's eggs are removed or eaten by the female, or expelled by her chick. Brood parasites include the cowbirds and many Old World cuckoos. Like amphibians, amniotes are air-breathing vertebrates, but they have complex eggs or embryos, including an amniotic membrane. Amniotes include reptiles (including dinosaurs and their descendants, birds) and mammals. Reptile eggs are often rubbery and are always initially white. They are able to survive in the air. Often the sex of the developing embryo is determined by the temperature of the surroundings,"
"most of the world's water bodies, both freshwater and marine. The rest of the vertebrate species are tetrapods, a single lineage that includes amphibians (with roughly 7,000 species); mammals (with approximately 5,500 species); and reptiles and birds (with about 20,000 species divided evenly between the two classes). Tetrapods comprise the dominant megafauna of most terrestrial environments and also include many partially or fully aquatic groups (e.g., sea snakes, penguins, cetaceans). There are several ways of classifying animals. Evolutionary systematics relies on anatomy, physiology and evolutionary history, which is determined through similarities in anatomy and, if possible, the genetics of organisms."
"to develop after it leaves the female's body. Unlike most vertebrates female birds typically have only one functional ovary and oviduct. As a group, birds, like mammals, are noted for their high level of parental care. Reptiles are almost all sexually dimorphic, and exhibit internal fertilization through the cloaca. Some reptiles lay eggs while others are viviparous (animals that deliver live young). Reproductive organs are found within the cloaca of reptiles. Most male reptiles have copulatory organs, which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis-like organ,"
"the amount of new territory favorable to amphibians. Given that among the hallmarks of amphibians are an obligatory return to a body of water to lay eggs, a delicate skin prone to desiccation (thereby often requiring the amphibian to be relatively close to water throughout its life), and a reputation of being a bellwether species for disrupted ecosystems due to the resulting low resilience to ecological change, amphibians were particularly devastated, with the Labyrinthodonts among the groups faring worst. In contrast, reptiles - whose amniotic eggs have a membrane that enables gas exchange out of water, and which thereby can"
"anatomically convergent. Birds and bats also share a high concentration of cerebrosides in the skin of their wings. This improves skin flexibility, a trait useful for flying animals; other mammals have a far lower concentration. The extinct pterosaurs independently evolved wings from their fore- and hindlimbs, while insects have wings that evolved separately from different organs. Flying squirrels and sugar gliders are much alike in their body plans, with gliding wings stretched between their limbs, but flying squirrels are placental mammals while sugar gliders are marsupials, widely separated within the mammal lineage. Insect mouthparts show many examples of convergent evolution."
"Amniote Amniotes (from Greek ἀμνίον ""amnion"", ""membrane surrounding the fetus"", earlier ""bowl in which the blood of sacrificed animals was caught"", from ἀμνός ""amnos"", ""lamb"") are a clade of tetrapod vertebrates comprising the reptiles, birds, and mammals. Amniotes lay their eggs on land or retain the fertilized egg within the mother, and are distinguished from the anamniotes (fishes and amphibians), which typically lay their eggs in water. Older sources, particularly prior to the 20th century, may refer to amniotes as ""higher vertebrates"" and anamniotes as ""lower vertebrates"", based on the discredited idea of the evolutionary great chain of being. Amniotes"
"common features among different animals, with some emphasis on the embryonic development of vertebrates and mammals. The egg cell is generally asymmetric, having an ""animal pole"" (future ectoderm and mesoderm) and a ""vegetal pole"" (future endoderm). It is covered with protective envelopes, with different layers. The first envelope – the one in contact with the membrane of the egg – is made of glycoproteins and is known as the vitelline membrane (zona pellucida in mammals). Different taxa show different cellular and acellular envelopes englobing the vitelline membrane. Fertilization (also known as 'conception', 'fecundation' and 'syngamy') is the fusion of gametes"
"taxonomy. Crocodilians (which include all modern crocodiles, alligators, and gharials) and birds flourish today. It is generally agreed that birds have the most species of all terrestrial vertebrates. Like the early tetrapods, early archosaurs had a sprawling gait because their hip sockets faced sideways, and the knobs at the tops of their femurs were in line with the femur. In the early to middle Triassic, some archosaur groups developed hip joints that allowed (or required) a more erect gait. This gave them greater stamina, because it avoided Carrier's constraint, i.e. they could run and breathe easily at the same time."
"relationships. For example, orangutans, gorillas, chimpanzees, and humans all belong to the same taxonomic grouping referred to as a family—in this case the family called Hominidae. These animals are grouped together because of similarities in morphology that come from common ancestry (called ""homology""). Strong evidence for evolution comes from the analysis of homologous structures: structures in different species that no longer perform the same task but which share a similar structure. Such is the case of the forelimbs of mammals. The forelimbs of a human, cat, whale, and bat all have strikingly similar bone structures. However, each of these four"
"bird bones. Something similar occurs with the respiratory system. In mammals, the total inner volume of lungs changes during ventilation. However, this does not happen in birds. They make the air circulate through their lungs by contracting and expanding their air sacs. Five genes are involved in this process in mammals and birds. Feathers are one of the most characteristic features of birds, alongside with the beak. Feathers are formed of α- and β-keratins. Compared to reptiles and mammals, α-keratin protein family has been reduced in birds, whereas β-keratins has expanded enormously. Since every major bird lineage possess at least"
"the reptile."" He also finds the eyes of birds and reptiles to be remarkably similar, especially the development of the lens, as well as the ear, which reveals a much wider gap between the Sauropsida and mammals than with birds. He describes the sexual organs of birds and reptiles to likewise be structurally similar, and finds that while most species of male bird have lost the penis to reduce weight, those that retain it bear remarkable similarities to extant reptiles. He writes that secondary sexual characteristics are also similar between birds and reptiles, with both groups frequently utilizing bright colors"
"but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic decline in amphibian populations for many species around the globe. The earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land. They diversified and became dominant during the Carboniferous and Permian periods, but were later displaced by reptiles and other vertebrates. Over time, amphibians shrank in"
"and that their X chromosome resembles the sex chromosome of birds, suggesting that the two sex chromosomes of marsupial and placental mammals evolved more recently than the split from the monotreme lineage. This feature, along with some other genetic similarities with birds, such as shared genes related to egg-laying, is thought to provide some insight into the most recent common ancestor of the synapsid lineage leading to mammals and the sauropsid lineage leading to birds and modern reptiles, which are believed to have split about 315 million years ago during the Carboniferous. The presence of vitellogenin genes (a protein necessary"
"This noise-induced alignment appears to be an intrinsic characteristic of collective coherent motion. Insect migration is the seasonal movement of insects, particularly those by species of dragonflies, beetles, butterflies and moths. The distance can vary from species to species, but in most cases these movements involve large numbers of individuals. In some cases the individuals that migrate in one direction may not return and the next generation may instead migrate in the opposite direction. This is a significant difference from bird migration. Monarch butterflies are especially noted for their lengthy annual migration. In North America they make massive southward migrations"
"the circulatory system. In general, birds have larger heart sizes and higher cardiac output. During flight, birds can sustain their heart rates, and their myosin flight muscles have better oxygen diffusion because of a high degree of branching between the capillaries. The common raven lives in a wide variety of climates. Due to its habitat and food, the common raven has unique features that allow it to regulate osmotic challenges. Common ravens can be observed in oceans consuming water. However, when birds consume salt loaded prey or drink salt water, the body’s internal osmoregularity increases. The solution produced is considerably"
"described, which means that over 95% of the described animal species in the world are invertebrates. The trait that is common to all invertebrates is the absence of a vertebral column (backbone): this creates a distinction between invertebrates and vertebrates. The distinction is one of convenience only; it is not based on any clear biologically homologous trait, any more than the common trait of having wings functionally unites insects, bats, and birds, or than not having wings unites tortoises, snails and sponges. Being animals, invertebrates are heterotrophs, and require sustenance in the form of the consumption of other organisms. With"
"steps towards reptiles, but the development of hard-shelled external eggs replacing the amphibious water bound eggs is the defining feature of the class Reptilia and is what allowed these amphibians to fully leave water. Another major difference from amphibians is the increased brain size, more specifically, the enlarged cerebrum and cerebellum. Although their brain size is small when compared to birds and mammals, these enhancements prove vital in hunting strategies of reptiles. The increased size of these two regions of the brain allowed for improved motor skills and an increase in sensory development. The origin of the reptiles lies about"
"birds. The end of the “Age of Reptiles” led to the “Age of Mammals”. Despite the change in phrasing, reptile diversification continued throughout the Cenozoic. Today, squamates make up the majority of extant reptiles today (over 90%). There are approximately 9,766 extant species of reptiles, compared with 5,400 species of mammals, so the number of reptilian species (without birds) is nearly twice the number of mammals. After the Cretaceous–Paleogene extinction event wiped out all of the non-avian dinosaurs (birds are generally regarded as the surviving dinosaurs) and several mammalian groups, placental and marsupial mammals diversified into many new forms and"
"of the water when the animal is floating. Valves seal the nostrils and ears when it is submerged. Unlike other reptiles, crocodilians have hearts with four chambers allowing complete separation of oxygenated and deoxygenated blood. Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic, have a high metabolic rate, a light skeletal system and powerful muscles. The long bones are thin, hollow and very light. Air sac extensions from the lungs occupy the centre of some bones. The sternum is"
"presumably similar habit. The earliest amniotes, including stem-reptiles (those amniotes closer to modern reptiles than to mammals), were largely overshadowed by larger stem-tetrapods, such as ""Cochleosaurus"", and remained a small, inconspicuous part of the fauna until the Carboniferous Rainforest Collapse. This sudden collapse affected several large groups. Primitive tetrapods were particularly devastated, while stem-reptiles fared better, being ecologically adapted to the drier conditions that followed. Primitive tetrapods, like modern amphibians, need to return to water to lay eggs; in contrast, amniotes, like modern reptiles – whose eggs possess a shell that allows them to be laid on land – were"
"these nested hierarchies was recognized by many biologists before Darwin, but he showed that his theory of evolution with its branching pattern of common descent could explain them. Darwin described how common descent could provide a logical basis for classification: An evolutionary tree (of Amniota, for example, the last common ancestor of mammals and reptiles, and all its descendants) illustrates the initial conditions causing evolutionary patterns of similarity (e.g., all Amniotes produce an egg that possesses the amnios) and the patterns of divergence amongst lineages (e.g., mammals and reptiles branching from the common ancestry in Amniota). Evolutionary trees provide conceptual"
"innovation in amniotes over amphibians is laying of eggs on land or having further evolved to retain the fertilized egg(s) within the mother. Amniote tetrapods began to dominate and drove most amphibian tetrapods to extinction. One group of amniotes diverged into the reptiles, which includes lepidosaurs, dinosaurs (which includes birds), crocodilians, turtles, and extinct relatives; while another group of amniotes diverged into the mammals and their extinct relatives. Amniotes include the tetrapods that further evolved for flight—such as birds from among the dinosaurs, and bats from among the mammals. The change from a body plan for breathing and navigating in"
"be as detrimental to birds, between the years of 1971 and 1995, a UK study revealed that 31% of the birds studied were laying their eggs an average of 9 days earlier in 1995 than in 1971. (P. 22) Mammals appear to be more resilient to the effects of climate change, as little evidence can be found of its impact on their populations or individuals. It has been established that there are genuine connections between fecundity and juvenile survival and winter temperatures. Also, distribution shifts northward and upward in elevation can be expected. (P. 23) Amphibians stand to be some"
"evolution seen in that new taxa. This is the main concept of phylogenetic inertia. Richard Dawkins also explained these constraints by likening natural selection to a river in his 1982 book ""The Extended Phenotype"". Birds are the only speciose group of vertebrates that are exclusively oviparous, or egg laying. It has been suggested that birds are phylogenetically constrained, as being derived from reptiles, and likely have not overcome this constraint or diverged far enough away to develop viviparity, or live birth. There have been several studies that have been able to effectively test for phylogenetic inertia when looking into shared"
"Oviparity Oviparous animals are animals that lay eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, reptiles, all birds, and the monotremes. In traditional usage, most insects, molluscs, and arachnids are also described as oviparous. The traditional modes of reproduction include oviparity, taken to be the ancestral condition, traditionally where either unfertilised oocytes or fertilised eggs are spawned, and viviparity traditionally including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body."
"Mammal Mammals ( from Latin ""mamma"" ""breast"") are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands, which in females produce milk for feeding (nursing) their young; a neocortex (a region of the brain); hair; and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha (shrews and allies). The next three are the Primates (apes, monkeys, and allies), the Cetartiodactyla (whales and even-toed ungulates), and the Carnivora (cats,"
"bird are analogous but not homologous, as they develop from quite different structures. A structure can be homologous at one level, but only analogous at another. Pterosaur, bird and bat wings are analogous as wings, but homologous as forelimbs because the organ served as a forearm (not a wing) in the last common ancestor of tetrapods, and evolved in different ways in the three groups. Thus, in the pterosaurs, the ""wing"" involves both the forelimb and the hindlimb. Analogy is called homoplasy in cladistics, and convergent or parallel evolution in evolutionary biology. Specialised terms are used in taxonomic research. Primary"