vertebrata

VERTEBRATA

Tetrapods of Patagonia

PHYLUM: Chordata	CLASS: Amphibia	CLASS: Reptilia	CLASS: Aves	CLASS: Mammalia
	Vertebrata	Amphibia	Reptils	Birds	Mammals
	Chordata - Vertebrata
	Chordates are defined as organisms that possess a structure called a notochord, at least during some part of their development. The notochord is a rod that extends most of the length of the body when it is fully developed. Lying dorsal to the gut but ventral to the central nervous system, it stiffens the body and acts as support during locomotion. Other characteristics shared by chordates include the following (from Hickman, 1994): bilateral symmetry segmented body, including segmented muscles three germ layers and a well-developed coelom. single, dorsal, hollow nerve cord, usually with an enlarged anterior end (brain) tail projecting beyond (posterior to) the anus at some stage of development pharyngeal pouches present at some stage of development ventral heart, with dorsal and ventral blood vessels and a closed blood system complete digestive system bony or cartilaginous endoskeleton usually present. Vertebrates, which include fishes, reptiles, amphibians, birds, and mammals, all share a vertebral column, or a chain of bony elements (vertebrae) that run along the dorsal surface from head to tail and form the main skeletal axis of the body. The vertebral column surrounds and more or less replaces the notochord as the chief "stiffener" of the body in locomotion. Some characteristics shared by most or all vertebrates (in addition to those traits shared among all chordates) include the following (after Hickman, 1994): integument of two divisions, including an outer epidermis and an inner dermis; integument often modified to produce hair, scales, feathers, glands, horn, etc. replacement of notochord by vertebral column more or less complete, depending on group bony or cartilaginous endoskeleton consisting of cranium, visceral arches, limb girdles, and 2 pairs of appendages muscular, perforated pharynx; this structure is the site of gills in fishes but is much reduced in adult land-dwelling forms (although it is extremely important in embryonic development of all vertebrates) movements provided by muscles attached to endoskeleton digestive system with large digestive glands, liver, and pancreas ventral heart with 2-4 chambers blood with red blood corpuscles containing hemoglobin, and in addition, white corpuscles well developed body cavity (coelom) containing visceral systems paired kidneys with ducts to drain waste to exterior most vertebrates with two sexes, each with paired gonads (there are some exceptions) general body plan consisting of head, trunk, 2 pairs of appendages, and postanal tail (but these structures are highly modified in many vertebrates and sometimes absent). The figure show a main structure of the chordata group. Petromyzontida Gnathostomata Placodermi Teleostomi Chondrichthyes Osteichthyes Actinopterygii Sarcopterygii Actinistia Choanata Dipnoi Tetrapoda Lissamphibia Gymnophiona Batrachia Caudata Anura Amniota Reptilia Testudines Sauria Lepidosauria Rhynchocephalia Squamata Archosauria Crocodylia Aves Mammalia
	Amphibia

	The name amphibian means "double life", and is given to members of this group for the double life that they lead. For while adult amphibians usually live on land, their soft eggs must be laid in the water. The eggs shown at left have just been shed by the female. This means that they have not yet been fertilized; the male sheds sperm over the eggs after they have been released into the water. Young amphibians, like the larval frog or tadpole, spend their early years in the water, breathing through gills in the side of their head in much the same way as fish do. In many ways they resemble fish more than they resemble their parents, for they have no legs, and swim by wriggling their tail. As they mature, amphibians will usually lose their gills and develop legs. A number of salamanders, such as the North American "mudpuppy" and the Mexican axolotl, develop legs but retain their larval gills and stay in the water throughout their lifetimes. This is a classic example of an evolutionary phenomenon known as neoteny -- the retention of larval or juvenile features in mature adults. Most amphibians have soft skin which easily absorbs water. This puts them in very close contact with their surroundings. It also makes them particularly susceptible to certain man-made toxins and pollutants. This may be why the number of amphibian species, and the size of many amphibian populations, has been declining in recent years. Amphibians, like the proverbial "canary in a coal mine," may be among the first organisms to suffer from the effects of global pollution and climate change -- providing an early warning of environmental degradation. Traditionally, the living amphibians have been grouped into three classes: Anura or Salientia -- frogs and toads Urodela or Caudata -- newts, salamanders, mudpuppies, etc. Gymnophiona -- caecilians These three groups have traditionally been classified together in the Lissamphibia. This grouping the Paleozoic amphibians, which were much more morphologically diverse. This theory has recently been challenged (Carroll, 1988); frogs, salamanders, and caecilians may have arisen separately, from among different ancestral Paleozoic amphibian groups. One problem in establishing the main lines of amphibian evolution is the relatively sparse fossil record; key groups such as the caecilians have very few fossils, and the early history of modern amphibian groups is not well known. Another problem is the fact that living anurans and caecilians are anatomically highly modified animals; frogs and toads are adapted for jumping, while caecilians have lost their limbs entirely and are modified for a burrowing lifestyle. Because these groups are so anatomically specialized, it is not easy to find unambiguous clues to their ancestry. Amphibios of Patagonia: BUFONIDAE: Bufo arenarum, Bufo rubropunctatus, Bufo spinulosos, Bufo variegatus. LEPTODACTYLIDAE: Alsodes gargola, Alsodes verrucosus, Atelogntathus sp., Atelognathus nitoi, Atelognathus patagonicus, Atelognathus praebasalticus, Atelognathus reverberii, Atelognathus salai, Atelognathus solitarius, Batrachyla antartandica, Batrachyla fitzroya, Batrachyla taeniata, Ceratophrys ornata, Eupsophus roseus, Hylorina sylvatica, Leptodactylus mystacinus, Leptodactylus ocellatus, Odontophrynus americanus, Odontophrunus occidentalis, Pleurodema bufonina, Pleurodema nebulosa, Pleurodema thaul, Somuncuria somuncurensis. RHINODERMATIDAE: Rhinoderma darwinii. HYLIDAE: Hyla pulchela.
	Reptils

	What is a reptile? Reptiles are vertebrates (they have a backbone). They have scaly skin and toes with claws. Reptiles have lungs and breathe air. Reptiles are hatched from eggs. Most reptiles depend upon their surroundings for warmth. Living reptiles include: snakes and lizards; turtles; the crocodilians; the tuatara and birds (dinosaur's descendants). Evolving from amphibians, the first reptiles appeared on Earth about 340 million years ago. Unlike amphibian eggs, reptile eggs are shelled and amniotic. The shell and amniotic fluid prevent the developing embro from drying out. Thus, reptile eggs do not need to be laid in or near water. Early reptiles had an advantage over amphibians of being able to adapt to a variety of habitats on an ever changing earth. Today, reptiles are found on land, in salt and fresh water and in the air (birds) from cool areas to tropics to deserts. Reptile eggs are generally soft and flexible. But some, like crocodiles, are hard. A yolk provides food for the developing embryo. Moisture and oxygen are absorbed through the porous shell. Animals whose eggs develop outside the mother's body are called oviparous. In some species of reptile the egg develops inside the body of the mother and the young are born alive (ovoviviparous). Animals whose unborn are nourished directly from the mother's bloodstream are viviparous. Although some reptiles tend their nest, most reptiles do not take care for their eggs. Reptiles have dry, scaly skin. They do not feel slimy. The scales are thickenings of the outside layer of skin and are mostly made of keratin, much like your fingernails. The outer skin is shed periodically allowing for growth. Most lizards shed their skin in patches, snakes usually shed the entire skin at one time. Scale patterns in the skin are often used to identify different species. Most reptiles are "cold-blooded" (ectothermic). They depend on the environmental temperature for the warmth that they need. They usually have a low metabolic rate, at least until they have warmed up. However, it is thought that some dinosaurs were warm-blooded and, of course, modern day birds are warm-blooded. From bony shells to sharp teeth, camouflage and warning colors, reptiles protect and defend themselves in a variety of ways. Some lizards are known for being able to shed their tail which enables them to get away from a predator. New tails are grown to replace the old but are composed of cartilage instead of bone. Playing dead, emitting a foul smell (stink pot turtle) or possessing venom are other forms of protection. Sea snakes, tiger snakes and the taipan are some of the most venomous of snakes. While there are numerous venomous snakes there are only two species of venomous lizards: the Gila Monster (found in the southwestern United States) and the Mexican Beaded Lizard (found in Mexico). Reptiles of Patagonia TESTUDINIDAE: Chelonoidis donosobarrosi. IGUANIDAE: Diplolaemus bibronii, Diplolaemus darwinii, Diplolaemus f. alto patagonica, Diplolaemus leopardinus, Leiosaurus bellii, Liolaemus altissimus, Liolaemus archeforus, Liolaemus austromendocinus, Liolaemus bibroni, Liolaemus boulengeri, Liolaemus buergeri, Liolaemus buergeri, Liolaemus ceii, Liolaemus chilensis, Liolaemus coeruleus, Liolaemus cyanogaster, Liolaemus darwini, Liolaemus donosobarrosi, Liolaemus elongatus, Liolaemus exploratorum, Liolaemus fitzingeri, Liolaemus fuscus, Liolaemus gracilis, Liolaemus kriegi, Liolaemus lemniscatus, Liolaemus lineomaculatus, Liolaemus magellanicus, Liolaemus melonops, Liolaemus multimaculatus, Liolaemus pictus, Liolaemus rothi, Liolaemus ruizieali, Liolaemus tenuis, Phymaturus palluma, Phymaturus patagonicus, Pristidacylus fasciatus, Pristidactylus scapulatus, Proctotretus pectinatus, Vilcunia periglacialis, Vilcunia silvanae. TEIIDAE: Tupinambis rufescens, Cnemidophorus longicaudus, Teius ocultatus. GECKKONIDAE: Homonota borellii, Homonota darwini, Homonota horrida. AMPHISBAENIDAE: Amphisbaena angustifrons, Anops kingi. LEPTOTYPHLOPIDAE: Leptotyphlops australis, Leptotyphlops borrichianus. COLUBRIDAE: Clelia rustica, Elapomorphus spegazzinii, Liophis sagitifer, Lystrophis dorbignyi, Lystrophis semicinctus, Oxyrhopus rhombifer, Philodryas patagoniensis, Philodryas psamophideus, Philodryas trilineatus, Pseudotomodon trigonatus, Tachymenis chilensis ELAPIDAE: Micrurus pyrrhocryptus CROTALIDAE: Bothrops alternatus, Bothrops ammodytoides.
	Birds

	Birds are vertebrates with feathers, modified for flight and for active metabolism. Birds are a monophyletic lineage, evolved once from a common ancestor, and all birds are related through that common origin. There are a few kinds of birds that don't fly, but their ancestors did, and these birds have secondarily lost the ability to fly. Modern birds have traits related to hot metabolism, and to flight: horny beak, no teeth large muscular stomach feathers large yolked, hard-shelled eggs. The parent bird provides extensive care of the young until it is grown, or gets some other bird to look after the young. strong skeleton There are about 30 orders of birds, about 180 families, and about 2,000 genera with 10,000 species. Most of them don't live in Michigan, though there are about 400 species that do.
	Mammals
	Class Mammalia
	All mammals share three characteristics not found in other animals: 3 middle ear bones; hair; and the production of milk by modified sweat glands called mammary glands. Mammals hear sounds after they are transmitted from the outside world to their inner ears by a chain of three bones, the malleus, incus, and stapes. Two of these, the malleus and incus, are derived from bones involved in jaw articulation in most other vertebrates. Mammals have hair. Adults of some species lose most of their hair, but hair is present at least during some phase of the ontogeny of all species. Mammalian hair, made of a protein called keratin, serves at least four functions. First, it slows the exchange of heat with the environment (insulation). Second, specialized hairs (whiskers or "vibrissae") have a sensory function, letting the owner know when it is in contact with an object in its external environment. These hairs are often richly innervated and well-supplied with muscles that control their position. Third, through their color and pattern, hairs affect the appearance of a mammal. They may serve to camouflage, to announce the presence of especially good defense systems (for example, the conspicuous color pattern of a skunk is a warning to predators), or to communicate social information (for example, threats, such as the erect hair on the back of a wolf; sex, such as the different colors of male and female capuchin monkeys; presence of danger, such as the white underside of the tail of a whitetailed deer). Fourth, hair provides some protection, either simply by providing an additional protective layer (against abrasion or sunburn, for example) or by taking on the form of dangerous spines that deter predators (porcupines, spiny rats, others). Mammals feed their newborn young with milk, a substance rich in fats and protein that is produced by modified sweat glands called mammary glands. These glands, which take a variety of shapes, are usually located on the ventral surface of females along paths that run from the chest region to the groin. They vary in number from two (one right, one left, as in humans) to a dozen or more. Other characteristics found in most mammals include highly differentiated teeth; teeth are replaced just once during an individual's life (this condition is called diphyodonty, and the first set is called "milk teeth); a lower jaw made up of a single bone, the dentary; four-chambered hearts, a secondary palate separating air and food passages in the mouth; a muscular diaphragm separating thoracic and abdominal cavities; highly developed brain; endothermy and homeothermy; separate sexes with the sex of an embryo being determined by the presence of a Y or 2 X chromosomes; and internal fertilization. The Class Mammalia includes around 5000 species placed in 26 orders (systematists do not yet agree on the exact number or on how some orders are related to others). Mammals can be found in all continents and seas. In part because of their high metabolic rates (associated with homeothermy and endothermy), they often play an ecological role that seems disproportionately large compared to their numerical abundance. Clasification Subclass Prototheria Order Monotremata -- Monotremes: platypus and echidnas Subclass Metatheria (marsupials) Order Didelphimorphia Order Paucituberculata Order Microbiotheria Order Dasyuromorphia Order Peramelemorphia Order Notoryctemorphia Order Diprotodontia Subclass Eutheria (placentals) Order Insectivora -- Insectivores: shrews, moles, hedgehogs, tenrecs, etc. Order Macroscelidea -- elephant shrews Order Scandentia -- tree shrews Order Dermoptera -- colugos Order Chiroptera --bats Order Primates --primates Order Xenarthra -- edentates; sloths, armadillos and anteaters Order Pholidota -- pangolins Order Lagomorpha -- rabbits and pikas Order Rodentia -- rodents Order Cetacea -- whales, dolphins, and porpoises Order Carnivora -- carnivores Order Tubulidentata --aardvark Order Proboscidea -- elephants Order Hyracoidea -- hyraxes Order Sirenia -- dugongs and manatees Order Perissodactyla -- horses, rhinos, tapirs Order Artiodactyla -- antelope, giraffe, camels, pigs, hippos, etc. Order Monotremata (2 Families; 3 genera) Monotremes are thought to have split from the lineage leading to other mammals sometime in the late Triassic. They are often placed in a separate subclass from other mammals, Prototheria. They retain many characters of their therapsid ancestors (for example, complex pectoral girdle, laying of eggs, limbs oriented with humerus and femur held lateral to body, and a cloaca). The skulls of monotremes are almost birdlike in appearance, with a long rostrum and smooth external appearance. Modern monotremes lack teeth as adults, sutures are hard to see, there is an elongate beak-like rostrum covered by a leathery sheath, and lacrimal bones are absent. Monotremes have several important mammalian characters, however, including fur (but they lack vibrissae), a four chambered heart, a single dentary bone, three middle ear bones, and the ability to lactate. Besides the absence of teeth, lacrimals, and obvious sutures, monotremes share a number of technical skeletal characteristics. On the skulls, the jugals are reduced or absent, the dentary is a slender bone with only a vestige of a coronoid process, the angle of the dentary is not inflected medially (unlike that of marsupials), auditory bullae are missing (part of the middle ear is enclosed by tympanic rings), and much of the wall of the braincase is made up by the petrosal rather than the alisphenoid (unlike all other modern mammals). Postcranially, the skeleton of monotremes is also unique among mammals. Their shoulder girdles are complex, including the standard components of modern mammals (scapula and clavicle), but also additional elements including coracoid, precoracoid, and interclavicle. The scapula, however, is simplified, lacking a supraspinous fossa. The shoulder girdle is much more rigidly attached to the axially skeleton than in other mammals. Femur and humerus are held roughly parallel to the ground when the animal walks, more in the fashion of therapsids and most modern reptiles than like modern mammals. Ribs are found on the neck (cervical) vertebrae as well as the chest (thoracic) vertebrae. Most of these characteristics are probably primitive, inherited from mammalian ancestors and lost in most or all other mammals. Another interesting skeletal characteristic of monotremes is the large epipubic bones in the pelvic region. They were originally thought to be related to having a pouch, but they are found in both males and females, and they also occur in all species of marsupials, whether they have a pouch or not. It is now thought that these bones are a vestige of the skeleton of therapsids, wherein they provide extra attachments for abdominal muscles to support the weight of the hind quarters. Monotremes are endothermic, but they have unusually low metabolic rates and maintain a body temperature that is lower than that of most other mammals. The eggs layed by monotremes are small (13-15 mm diameter) and covered by a leathery shell. They contain a large yolk. Only the left ovary is functional in the platypus, but both produce eggs in the echidna. Like the eggs of birds, monotreme eggs are incubated and hatched outside the body of the mother. Incubation lasts about 12 days. The young are protected in a temporary pouch and are fed milk produced by mammary glands; the milk is secreted onto the skin within the pouch and sucked or lapped up by the young monotremes. The nursing period is prolonged, with weaning at 16-20 weeks. All male monotremes have spurs on their ankles that are presumed to be used in fighting and in defense. In one family (Ornithorhynchidae) there is a groove along the spur that carries poison secreted by adjacent glands. Monotremes are restricted to Australia and New Guinea.

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