Which feature do mammals share in common with all vertebrates?
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ver·te·brate (vûr'tə-brĭt, -brāt') pronunciation\nadj.\n\n   1. Having a backbone or spinal column.\n   2. Of or characteristic of vertebrates or a vertebrate.\n\nn.\n\nA member of the subphylum Vertebrata, a primary division of the phylum Chordata that includes the fishes, amphibians, reptiles, birds, and mammals, all of which are characterized by a segmented spinal column and a distinct well-differentiated head.\n\n[Latin vertebrātus, having joints, from vertebra, vertebra.]
34312
alecithal, like most mammals.
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That's an interesting question!\nThe short answer would be "Different evolutionary paths", which is true. But those paths imply adaptive and functional differences. \nThe teeth of sharks are not too different from those of other tetrapods. Aside from birds, most tetrapods have many generations of teeth (this is called polyphyodonty), and those teeth are usually not strongly attached to the jaws. They`re more or less easily lost and replaced during normal activities. So, why don't we mammals have such a useful feature? \nThe loss of all those teeth replacements was a tradeoff for our acquisition of better tooth occlusion. Occlusion is the way the surfaces of the upper and lower teeth contact each other, and in mammals, our chewing teeth (molars and premolars) have complex occlusal surfaces, which allow for slicing food (shearing like scissors), crushing food (cusps and basins that act like a mortar and pestle), and other ways of basically, disintegrating food items. \nThe thing is, the precise interlocking of cusps and vales is not easy to achieve (as anybody with occlusion problems has probably heard from the dentist). So the hypothesis is that the evolutionary path of mammals "focused" on one generation of perfectly occluding teeth. Thus, molars erupt late in life, grow slowly, and are not replaced. And the other teeth (incisors, canines and premolars) have a first, "milk" teeth generation that allows the young mammal to feed while its skull is expanding. Then, by the time its growth has slowed down, the definitive teeth erupt and take their places (they would not fit in the small jaws).\nThe teeth of man, as those of all primates, are brachydont. This means that they don't keep growing once they've erupted completely. However, the enamel that forms the outer cover of the teeth is the hardest substance in our bodies, and is able to endure the wear from our food. However, many other mammals that eat more abrasive foods (plants, and especially grasses) have permanently growing teeth (hypsodonty). This is, in a way, the equivalent of having multiple generations of teeth; their teeth keep growing throughout part of their lives (as in the case of horses) or all of their lives (like many rodents and ruminants). But we cannot "recover" the capacity for multiple teeth generations that we "gave up" evolutionarily when we became mammals.
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All animals that have mammary glands to produce and feed their young ones with MILK are mammals. So Rodents like rats,mice and bandicoots are all mammals.BUT all mammals are not rodents. Lions and Elephants ARE mammals but they are NOT rodents.All human beings are mammals.But are they rodents? The last example will clear any doubt in your mind.\nRodents have their own peculiarities, which set them apart from other mammals.\nThey have burrowing habits, the front teeth or the incisors are longer than the others, sharp and pointed. They continue to grow for long. Therefore. The animal must constantly ‘GNAW’ at something to keep them trim and sharp.\n Besides the examples quoted above; the others in the category of rodents are rabbits, hares, squirrels and otters. They all come under class- Mammalia and order-Rodentia.
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An animal is defined as a multicellular, eukaryotic organism that has to eat food to obtain energy and does not have chitinous cell walls. These characteristics set animals apart from all the other kingdoms of life: plants (which have cell walls, but make their own food), fungi (which have cell walls), protists (unicellular), monera (prokaryotic, unicellular).
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Primates are relatively primitive with respect to other mammals, that is, our characteristics are fairly generalized, with the addition of adaptive characters related to arboreality (life on trees) and sociality. We're related to the Scandentia (tupayas or tree shrews) so we were probably insectivore-like arboreal mammals. If we go further back, we meet the Chiroptera (bats) - Dermoptera (flying lemurs) which have their own specializations. Probably the primates evolved from animals not unlike the first known mammals from the Mesozoic, such as Morganucodon: small shrew-like animals, that evolved toward life on trees.
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Because the current classification system is based on homologies, and not analogies. \nHomologous structures have the same origins and are derived from a common structure that existed in an ancestral form. They may have similar functions or not, for instance some of the bones that are found in the mandible of reptiles are transformed into the middle-ear ossicles of mammals: different function, but same origin. Other obvious homologies are the bones in our hand and those in the flipper of a dolphin: same origin, mostly same bones, different function.\nThe similarities between bats and birds are due to adaptations to a flying morphotype, but although the bones forming both bats' and birds' wings are the same (because both have evolved from a tetrapod ancestor with those bones), they don't have a _common ancestor_ that had wings; therefore this trait is not useful for grouping tem.  Their flight was acquired independently.\nThe similarities are convergent, not homologous.
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Convergent evolution means that two animals evolve to have similar traits, even though there arent genetically related.  The traits are those that are driven by environment.  For example, both fish and ocean mammals have fins and a generally similar body shape, yet are vastly different genetically.  The formation of fins and streamlined body is the best solution for moving through water, so both animals evolved them-of interest, large fish, such as sharks, have vertical tailfins, while ocean living mammals have horizontal tailfins.
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All of the terrestrial vertebrates have four limbs (and thus, they are sometimes referred to as tetrapods, which literally means 'four feet').\n\nNot only that, but they all have the same basic structure of limb bones - pectoral girdle consisting of scapulae, with the humerus as the single upper arm bones, radius and ulna as the two lower arm bones and a wrist made up of carpal bones, followed by metacarpals and digits made up of phalanges.  The lower limb girdle is also nearly identical, with a pelvis, femurs, tibia/fibulla, tarsals, metatarsals and phalanges.\n\nThis incredible similarity of structure in limb bones between incredible diverse groups of organisms - chickens, frogs, salamanders, whales, lions, humans, seals, plesiosaurs, iguanas, horses, mice and platypus all have this same exact limb structure, is evidence that all of these organisms share a common ancestor that also had this limb arrangement.\n\nStrangely enough, the remaining vertebrate group, the fish, do not all share this limb bone arrangement.  Most of them have the same set-up of pectoral and pelvic limbs, but after that, there's a whole variety of totally different skeletal anatomy.\n\nThere is one group of fish that does have this limb arrangement though.  Most of them are only known as fossils today, but there is one living species of this group.  The sarcopterygians, or lobe-finned fish were the first known group to show this particular limb pattern.  The coelacanth also possesses the pattern.\n\nStrangely enough, the earliest known fossils of amphibians look amazingly similar to sarcopterygian fish with larger limbs.\n\nThis conservation of characters amongst all living terrestrial vertebrates is pretty powerful evidence for evolution having taken place, and that all of these diverse organisms developed through common descent from a single ancestor that first evolved this character.
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Homologous structures are structures showing similar characteristics based on common shared ancestry.\nIf you look at the "arms" in mammals you can find homologous structures between the wings of a bat, the arms of humans and the frontal fins of whales - similar bones specialized and adapted but following the same building plan inherited from an early forefather.
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Kingdom: Animalia (is an animal)\nPhylum: Chordata (has a notochord at some stage)\nSubphylum: Vertebrata (has a spinal column - backbone)\nClass: Mammalia (is a mammal: warm-blooded, suckles young with milk)
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Homologus structures have the same function and evolved along the same pathway- example- all mammals have hair that evolved from one common ancestor. Hair in mammals is a homologus structure.\n\nAnalogous Structures have the same function but evolved diffrently. Birds and butterflies both fly with wings, but the birds and insects didn't evovle wings from the same common ancestor.
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i think animalia contains all animals - fish, reptiles, mammals, birds and amphibians. dolphins are obviously not bacteria, fungi, insects, etc. if you meant mammalia it is because dolphins -\nbreathe air with lungs, not gills\nbreastfeed their young that do not hatch from eggs\nhave four chambered hearts
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How does the snake's vertebra indicate that it evolved to support slithering? (Answer: Snakes have a large number of vertebrae, which are connected together by ball-and socket joints. These characteristics allow extreme flexibility. Together with specialized muscles, the vertebra enable the snake to move with speed and agility. See ref.)
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most mammals have four appendages, they just evolved differently. humans evolved into arms and legs with very different uses. rodent type animals have front feet they can use as hands, as do most monkeys. beasts of burden and their predators maintained four legs for obvious reasons.
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Animals and plants develope unique features that help them to adapt to their enviroment.
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It is the comparative similarity in embryos of vertabrae orgaisms.  An example is if you look at several vertabrae organisms (example: human, chicken, turtle embryos) they will look similar.  This suggests that they have a recent common ancestor since they have similar developmental/early anatomical traits.