File Name: feeding form function and evolution in tetrapod vertebrates .zip
As the first four-legged vertebrates, called tetrapods, crept up along the shores of ancient primordial seas, feeding was among the most paramount of their concerns. Looking back into the mists of evolutionary time, fish-like ancestors can be seen transformed by natural selection and other evolutionary pressures into animals with feeding habitats as varied as an anteater and a whale. From frog to pheasant and salamander to snake, every lineage of tetrapods has evolved unique feeding anatomy and behavior.
It includes extant and extinct amphibians , reptiles including dinosaurs and therefore birds , and synapsids including mammals. Tetrapods evolved from a group of animals known as the Tetrapodomorpha which, in turn, evolved from ancient sarcopterygian fish around million years ago in the middle Devonian period ;  their forms were transitional between lobe-finned fishes and the four-limbed tetrapods.
The first tetrapods from a traditional, apomorphy -based perspective appeared by the late Devonian, The change from a body plan for breathing and navigating in water to a body plan enabling the animal to move on land is one of the most profound evolutionary changes known.
Modern amphibians , which evolved from earlier groups , are generally semiaquatic; the first stage of their lives is as fish-like tadpoles , and later stages are partly terrestrial and partly aquatic.
However, most tetrapod species today are amniotes , most of those are terrestrial tetrapods whose branch evolved from earlier tetrapods about million years ago crown amniotes evolved million years ago. The key 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.
Some tetrapods, such as the snakes , have lost some or all of their limbs through further speciation and evolution; some have only concealed vestigial bones as a remnant of the limbs of their distant ancestors. Others returned to being amphibious or otherwise living partially or fully aquatic lives, the first during the Carboniferous period ,  others as recently as the Cenozoic.
Tetrapods have numerous anatomical and physiological features that are distinct from their aquatic ancestors. These include the structure of the jaw and teeth for feeding on land, limb girdles and extremities for land locomotion, lungs for respiration in air, a heart for circulation, and eyes and ears for seeing and hearing in air.
Tetrapods can be defined in cladistics as the nearest common ancestor of all living amphibians the lissamphibians and all living amniotes reptiles, birds, and mammals , along with all of the descendants of that ancestor. This is a node-based definition the node being the nearest common ancestor.
The group so defined is the crown group, or crown tetrapods. The term tetrapodomorph is used for the stem-based definition: any animal that is more closely related to living amphibians, reptiles, birds, and mammals than to living dipnoi lungfishes.
The group so defined is known as the tetrapod total group. Stegocephalia is a larger group equivalent to some broader uses of the word tetrapod , used by scientists who prefer to reserve tetrapod for the crown group based on the nearest common ancestor of living forms. The two subclades of crown tetrapods are Batrachomorpha and Reptiliomorpha. Batrachomorphs are all animals sharing a more recent common ancestry with living amphibians than with living amniotes reptiles, birds, and mammals.
Reptiliomorphs are all animals sharing a more recent common ancestry with living amniotes than with living amphibians. Tetrapoda includes four living classes: amphibians, reptiles, mammals, and birds.
Overall, the biodiversity of lissamphibians ,  as well as of tetrapods generally,  has grown exponentially over time; the more than 30, species living today are descended from a single amphibian group in the Early to Middle Devonian. However, that diversification process was interrupted at least a few times by major biological crises, such as the Permian—Triassic extinction event , which at least affected amniotes.
As biodiversity has grown, so has the number of niches that tetrapods have occupied. The first tetrapods were aquatic and fed primarily on fish. Today, the Earth supports a great diversity of tetrapods that live in many habitats and subsist on a variety of diets. The classification of tetrapods has a long history.
Traditionally, tetrapods are divided into four classes based on gross anatomical and physiological traits. Similar considerations apply to caecilians and aquatic mammals.
Newer taxonomy is frequently based on cladistics instead, giving a variable number of major "branches" clades of the tetrapod family tree. As is the case throughout evolutionary biology today, there is debate over how to properly classify the groups within Tetrapoda. Traditional biological classification sometimes fails to recognize evolutionary transitions between older groups and descendant groups with markedly different characteristics.
For example, the birds, which evolved from the dinosaurs, are defined as a separate group from them, because they represent a distinct new type of physical form and functionality. In phylogenetic nomenclature , in contrast, the newer group is always included in the old. For this school of taxonomy, dinosaurs and birds are not groups in contrast to each other, but rather birds are a sub-type of dinosaurs. The tetrapods, including all large- and medium-sized land animals, have been among the best understood animals since earliest times.
By Aristotle 's time, the basic division between mammals, birds and egg-laying tetrapods the " herptiles " was well known, and the inclusion of the legless snakes into this group was likewise recognized.
With the basic classification of tetrapods settled, a half a century followed where the classification of living and fossil groups was predominately done by experts working within classes.
In the early s, American vertebrate palaeontologist Alfred Romer — produced an overview, drawing together taxonomic work from the various subfields to create an orderly taxonomy in his Vertebrate Paleontology. Benton and Knobill and Neill This classification is the one most commonly encountered in school textbooks and popular works.
While orderly and easy to use, it has come under critique from cladistics. The earliest tetrapods are grouped under Class Amphibia, although several of the groups are more closely related to amniotes than to modern day amphibians. Traditionally, birds are not considered a type of reptile, but crocodiles are more closely related to birds than they are to other reptiles, such as lizards. Birds themselves are thought to be descendants of theropod dinosaurs.
Basal non-mammalian synapsids "mammal-like reptiles" traditionally also sort under Class Reptilia as a separate subclass,  but they are more closely related to mammals than to living reptiles. Considerations like these have led some authors to argue for a new classification based purely on phylogeny , disregarding the anatomy and physiology.
Tetrapods evolved from early bony fishes Osteichthyes , specifically from the tetrapodomorph branch of lobe-finned fishes Sarcopterygii , living in the early to middle Devonian period. The first tetrapods probably evolved in the Emsian stage of the Early Devonian from Tetrapodomorph fish living in shallow water environments.
The earliest tetrapods inhabited saltwater, brackish-water, and freshwater environments, as well as environments of highly variable salinity. These traits were shared with many early lobed-finned fishes. As early tetrapods are found on two Devonian continents, Laurussia Euramerica and Gondwana , as well as the island of North China , it is widely supposed that early tetrapods were capable of swimming across the shallow and relatively narrow continental-shelf seas that separated these landmasses.
Since the early 20th century, several families of tetrapodomorph fishes have been proposed as the nearest relatives of tetrapods, among them the rhizodonts notably Sauripterus ,   the osteolepidids , the tristichopterids notably Eusthenopteron , and more recently the elpistostegalians also known as Panderichthyida notably the genus Tiktaalik.
A notable feature of Tiktaalik is the absence of bones covering the gills. These bones would otherwise connect the shoulder girdle with skull, making the shoulder girdle part of the skull.
With the loss of the gill-covering bones, the shoulder girdle is separated from the skull, connected to the torso by muscle and other soft-tissue connections.
The result is the appearance of the neck. This feature appears only in tetrapods and Tiktaalik , not other tetrapodomorph fishes. Tiktaalik also had a pattern of bones in the skull roof upper half of the skull that is similar to the end-Devonian tetrapod Ichthyostega.
The two also shared a semi-rigid ribcage of overlapping ribs, which may have substituted for a rigid spine. In conjunction with robust forelimbs and shoulder girdle, both Tiktaalik and Ichthyostega may have had the ability to locomote on land in the manner of a seal, with the forward portion of the torso elevated, the hind part dragging behind.
Finally, Tiktaalik fin bones are somewhat similar to the limb bones of tetrapods. However, there are issues with positing Tiktaalik as a tetrapod ancestor. For example, it had a long spine with far more vertebrae than any known tetrapod or other tetrapodomorph fish. Also the oldest tetrapod trace fossils tracks and trackways predate it by a considerable margin. Several hypotheses have been proposed to explain this date discrepancy: 1 The nearest common ancestor of tetrapods and Tiktaalik dates to the Early Devonian.
By this hypothesis, the lineage is the closest to tetrapods, but Tiktaalik itself was a late-surviving relic.
Actinistia Coelacanths. Dipnoi Lungfish. The lagoon was inhabited by a variety of marine organisms and was apparently salt water. The average water temperature was 30 degrees C 86 F.
These include Elginerpeton and Obruchevichthys. All known forms of Frasnian tetrapods became extinct in the Late Devonian extinction , also known as the end-Frasnian extinction. The oldest near-complete tetrapod fossils, Acanthostega and Ichthyostega , date from the second half of the Fammennian. There is no evidence that it did so, only that it may have been anatomically capable of doing so.
The publication in of Tutusius umlambo and Umzantsia amazana from high latitude Gondwana setting indicate that the tetrapods enjoyed a global distribution by the end of the Devonian and even extend into the high latitudes.
The end-Fammenian marked another extinction, known as the end-Fammenian extinction or the Hangenberg event , which is followed by another gap in the tetrapod fossil record, Romer's gap , also known as the Tournaisian gap.
Tetrapod-like vertebrates first appeared in the early Devonian period. The Devonian stem-tetrapods went through two major bottlenecks during the Late Devonian extinctions , also known as the end-Frasnian and end-Fammenian extinctions.
These extinction events led to the disappearance of stem-tetrapods with fish-like features. During the early Carboniferous, the number of digits on hands and feet of stem-tetrapods became standardized at no more than five, as lineages with more digits died out.
By mid-Carboniferous times, the stem-tetrapods had radiated into two branches of true "crown group" tetrapods. Modern amphibians are derived from either the temnospondyls or the lepospondyls or possibly both , whereas the anthracosaurs were the relatives and ancestors of the amniotes reptiles, mammals, and kin.
The first amniotes are known from the early part of the Late Carboniferous. All basal amniotes, like basal batrachomorphs and reptiliomorphs, had a small body size. The sudden collapse of a vital ecosystem shifted the diversity and abundance of major groups. Amniotes were more suited to the new conditions.
They invaded new ecological niches and began diversifying their diets to include plants and other tetrapods, previously having been limited to insects and fish. In the Permian period, in addition to temnospondyl and anthracosaur clades, there were two important clades of amniote tetrapods, the sauropsids and the synapsids. The latter were the most important and successful Permian animals.
The end of the Permian saw a major turnover in fauna during the Permian—Triassic extinction event. There was a protracted loss of species, due to multiple extinction pulses. The diapsids a subgroup of the sauropsids began to diversify during the Triassic , giving rise to the turtles , crocodiles , and dinosaurs.
In the Jurassic , lizards developed from other diapsids. In the Cretaceous , snakes developed from lizards and modern birds branched from a group of theropod dinosaurs. By the late Mesozoic, the groups of large, primitive tetrapod that first appeared during the Paleozoic such as temnospondyls and amniote-like tetrapods had gone extinct.
Alan H. Copeia 1 December ; 4 : — Kurt Schwenk ed. Academic Press, San Diego, California. ISBN
Vincent Bels was born in Verviers, Belgium. His Ph. He has used lizards as a model to clarify the process of behavioral ritualization in evolution. He then taught Biology, Zoology and Ecology and developed applied research methods for studying feeding behavior in domestic animals at the Hautes Ecoles Hainaut, Belgium and the Associated Agronomic Centre Belgium. He has authored over 90 peer-reviewed articles, 10 book chapters, and 6 books on feeding and locomotion in vertebrates. Ian Q. Whishaw received his Ph.
Amphibian , class Amphibia , any member of the group of vertebrate animals characterized by their ability to exploit both aquatic and terrestrial habitats. Approximately 8, species of living amphibians are known. First appearing about million years ago during the Middle Mississippian Epoch , they were one of the earliest groups to diverge from ancestral fish-tetrapod stock during the evolution of animals from strictly aquatic forms to terrestrial types. Today amphibians are represented by frogs and toads order Anura , newts and salamanders order Caudata , and caecilians order Gymnophiona. These three orders of living amphibians are thought to derive from a single radiation of ancient amphibians, and although strikingly different in body form, they are probably the closest relatives to one another. As a group, the three orders make up subclass Lissamphibia.
Sitaatteja vuodessa. Seuraavat artikkelit on yhdistetty Scholar-palvelussa. Yhdistetyt sitaatit. Oma profiili Oma kirjasto Tiedot Ilmoitukset. Vertebrate morphology Vertebrate feeding Phenotypic evolution Evolutionary constraint Squamate chemoreception.
Keliopas Krey Papua University Indonesia. Bessler, S.
It includes extant and extinct amphibians , reptiles including dinosaurs and therefore birds , and synapsids including mammals. Tetrapods evolved from a group of animals known as the Tetrapodomorpha which, in turn, evolved from ancient sarcopterygian fish around million years ago in the middle Devonian period ;  their forms were transitional between lobe-finned fishes and the four-limbed tetrapods. The first tetrapods from a traditional, apomorphy -based perspective appeared by the late Devonian, The change from a body plan for breathing and navigating in water to a body plan enabling the animal to move on land is one of the most profound evolutionary changes known. Modern amphibians , which evolved from earlier groups , are generally semiaquatic; the first stage of their lives is as fish-like tadpoles , and later stages are partly terrestrial and partly aquatic. However, most tetrapod species today are amniotes , most of those are terrestrial tetrapods whose branch evolved from earlier tetrapods about million years ago crown amniotes evolved million years ago.
Vertebrate neck musculature spans the transition zone between head and trunk. The extent to which the cucullaris muscle is a cranial muscle allied with the gill levators of anamniotes or is instead a trunk muscle is an ongoing debate. Novel computed tomography datasets reveal broad conservation of the cucullaris in gnathostomes, including coelacanth and caecilian, two sarcopterygians previously thought to lack it.
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