It's obvious that mammals and birds do, but I don't see it in snakes or lizards.
131381
They feel fear and rage. Primitive emotions, not higher more complex ones like love or sympathy.
561125
Does a snake have legs?
492095
depends on how you see them..many see them as huge reptiles and other as the precursor to birds. I personally have always though of them as cold blooded but my opinion is now changing because of the various locations of fossils (montana, Canada, russia)..
612991
Eptiles do not use water to flush nitrogenous wastes from the body as urine, like mammals do, but convert them to a form which can be dumped as solid dung.\n\nDiverse lizards of Oz\nNext to birds, lizards are among the most commonly encountered vertebrate animals in the savannas. Indeed, the diversity of lizards in the tropical savannas is particularly rich, exploiting numerous habitats, from woodlands to sandstone escarpments, rainforests and semi-arid zones, many endemic to just small areas.\n\nEvolution of lizards\nThe combination of poor soils and dry climate is believed to have led to the evolution of plants with tough, thick, chemical-laden leaves—and relatively few plant-eaters. Instead, the vegetation is broken down by termites, which thrive in Australia—providing an abundant food source for reptiles. Just as mangroves don’t need salt but have developed strategies for living where no other plants can compete, so too have reptiles exploited an environment largely uninhabitable for other animals.\n\nThe great diversity of reptile species may be due to the long-term stability, and great size, of the Australian continent. Those animals which cope well with conditions have had plenty of time to evolve into different species exploiting different ecological niches. This diversity may even be fostered by shortages. This may favour large numbers of specialist species which have adapted to localised conditions over fewer, more widely distributed, species which might have evolved in a more benign environment.\n\nEfficiency of lizards\nExcepting Antarctica, Australia is the driest continent on earth; 75 per cent of it is arid or semi-arid. The climate is erratic, with long, irregular dry and wet cycles determined by the effects of El Nino and La Nina. Successful animals must cope with unreliable rainfall and prolonged periods of shortages, but take advantage of unpredictable times of plenty. In addition, Australia’s soils are also nutrient-poor, with low productivity, and fires are frequent. Energy-efficiency is thus the key to long-term survival.\n\nMammals and birds generate their own heat from food, using up to 90 per cent of their energy intake for this purpose. However most lizards, instead of consuming food to generate energy, use solar power, basking in sunshine or sleeping in a warm spot to power up their ‘batteries’ for the day’s (or night’s) activities.\n\nSome lizards, such as dragons, are able to raise their ribs and angle their bodies to increase the body surface exposed and can become darker to absorb more heat. This strategy, known as thermoregulating, is not an option for some lizards which live in closed forests. Instead, they thermoregulate passively, or ‘thermoconform’, their body temperature simply conforming to that of the air around them.\n\nLizards are also efficient users of water. Their dry scaly skin reduces moisture loss, those living in the hottest areas tending to have compact bodies to minimise loss and/or restricting most activities to hours of darkness. In addition, reptiles do not use water to flush nitrogenous wastes from the body as urine, like mammals do, but convert them to a form which can be dumped as solid dung.\n\nGetting away from predators\nGeckos, legless lizards and skinks will readily drop their tails when threatened, the wriggling appendage serving as a distraction while the owner makes its getaway. Fracture planes between certain vertebrae at the top of the tail allow it to detach easily when pulled apart by special muscles. This sacrificial offering is easily regrown. Tails of dragons and goannas can also break off, but do not do so as readily and tend not to regrow. All dragons, goannas and Australian geckos lay eggs but some skinks give birth to live young. Experiments with skink eggs suggested that those kept at ‘maternal’ temperatures were larger and fitter than those kept at normal nest temperatures. This may be an important factor in cool, or dry, clima
101429
The answer to your question is twofold:\n\nThe bone structure of birds is indeed very different from that of mammals and other non-flying vertebrates. Their bones have a resistant outer layer, but the inner part is mostly hollow and in many cases invaded by the air sacs (part of the respiratory system). Therefore they're structurally different.\n\nOn the other hand, the structure of a bird's skeleton is different from mammals too. They have some fusions of bones that contribute to their stability and rigidity, and their hands have only 3 fingers. Their skull has no sutures, most have a keeled sternum and very different vertebrae.
428358
Because it's warm-blooded,  has fur, and gives milk.  (Even though it also lays eggs, which is very un-mammalian, scientists just agreed to classify it that way because it's more like a mammal than anything else.)
263387
You would think that the pecking itself or the usage pattern of (as it were) of the pecker would be enough to identify not only the sub-species but the individual, however, there is not scientific evidence to show that this is the case. \n\nIt is possible through the use of photgraphs of the peckers to identfy even beyond the sub-species to the invidual (there are a few famous cases of this).
494265
No. But that does NOT mean bulls are colorblind. Many mammals cannot tell the difference between red and green, but do see more than black and white.\n\nMammals in general have poorer color vision than birds and reptiles. This is believed to be because they were nocturnal scavengers early on in evolution and eventually lost 2 of the 4 types of cells in the eye that allow us to see color. These are known as cone cells.\n\nSome primates, such as humans, have regained a 3rd type of cone cell. Thus allowing them to tell the difference between red and green. Being that this is an evolutionary new cone, it is no surprise that this newer color distinction is more commonly lost than the older blue and yellow.
219338
One of the arguments would be the lack of fossils for intermediate species. As there are many fish and reptiles fossils discovered, shouldn't there be at least some half fish-half reptile fossils as well?
242791
It would take a while to look up, but the mineral content does not vary significantly between any mammals, so human mineral content would be sufficient.  In fact, I doubt if the mineral content varies more than a tiny amount between mammals and birds.
77423
While it might be possible that some of these creatures exist, it certainly can't be said to be 'probable'.\n\nWe are still finding new species of mammals and birds all the time.  Genetic studies have even shown us that some of the critters we thought we knew are more diverse than we thought.\n\nRecently it was discovered that the species we know as the African elephant is in fact two species, a savannah species and a forest species.  So we have 'found' one of the largest species of land mammal just in the last few years.  Another study found that there was a population of the Bactrian camel (the one with two humps) that was actually a separate species too.\n\nSo it is possible that there may be some critter hidden off in the deep forest somewhere that we've never seen before.  But the chances of something like Bigfoot/Sasquatch remaining undiscovered in the rather well explored forests of North America are rather low.\n\nThe best chance for new, exciting and incredible discoveries are in the seas.  We really have barely scratched the surface in our exploration there, and there could be all kinds of new, even huge and exciting finds down there.\n\nJust in the last few years, the Megasquid was described, whose body is larger than that of the Giant Squid (although the tentacles aren't as long), actual live footage of the Giant Squid was finally taken, and Coelacanths were found off the coast of Indonesia, 10 000 km from where it was thought was the only place they existed.
552057
most people believe that animals don't have they basic intelligence to understand what you might say to them let alone understanding religion.  However since they are cold-blooded, I would say the sun.
243548
If snakes evolved from land dwelling creatures, then those land dwelling creatures evolved from sea creatures.  After all, humans evolved on land.
323259
The phylogeny of snakes is poorly known due to the fact that snake skeletons are typically small and fragile, making fossilization unlikely. It has however been generally agreed, on the basis of morphology, that snakes descended from lizard-like ancestors. Recent research based on genetics and biochemistry confirms this; snakes form a venom clade with several extant lizard families.\n\nRecent fossil evidence suggests that snakes directly evolved from burrowing lizards, either varanids or some other group. An early fossil snake, Najash rionegrina, was a two-legged burrowing animal with a sacrum, fully terrestrial. One extant analog of these putative ancestors is the earless monitor Lanthanotus of Borneo, although it also is semi-aquatic. As these ancestors became more subterranean, they lost their limbs and became more streamlined for burrowing. Features such as the transparent, fused eyelids and loss of external ears, according to this hypothesis, evolved to combat subterranean conditions (scratched corneas, dirt in the ears). According to this hypothesis, snakes re-emerged onto the surface of the land much as they are today. Other primitive snakes are known to have possessed hindlimbs but lacked a direct connection of the pelvic bones to the vertebrae, including Haasiophis, Pachyrhachis and Eupodophis) which are slightly older than Najash.\n\nThe alternative hypothesis, based on morphology, suggests that ancestors were related to mosasaurs — extinct aquatic reptiles from the Cretaceous — which in turn are thought to have derived from varanid lizards. Under this hypothesis, the fused, transparent eyelids of snakes are thought to have evolved to combat marine conditions (corneal water loss through osmosis), while the external ears were lost through disuse in an aquatic environment, ultimately leading to an animal similar in appearance to sea snakes of today. In the Late Cretaceous, snakes re-colonized the land much like they are today. Fossil snake remains are known from early Late Cretateous marine sediments, which is consistent with this hypothesis, particularly as they are older than the terrestrial Najash rionegrina. Similar skull structure; reduced/absent limbs; and other anatomical features found in both mosasaurs and snakes lead to a positive cladistical correlation, though some features are also shared with varanids. Supposedly similar locomotion for both groups is also used as support for this hypothesis. Genetic studies have indicated that snakes are not especially related to monitor lizards, and (it has been claimed) therefore not to mosasaurs, the proposed ancestor in the aquatic scenario of their evolution. However, there is more evidence linking mosasaurs to snakes than to varanids. Fragmentary remains that have been found from the Jurassic and Early Cretaceous indicate deeper fossil records for these groups, which may eventually refute either hypothesis.\n\nThe great diversity of modern snakes appeared in the Paleocene, probably correlated with the adaptive radiation of mammals following the extinction of the dinosaurs.
403
The fact that female mammals produce milk for their young means that at birth a mammal can have a relatively large brain, although they are relatively helpless.  Other animals have to be able to at least get around.\n\nBrains don't grow as much as other parts of the body, which is why babies seem to have large heads.\n\nThe obvious counter-example is birds, where the young are stuck in the nest and depend on their parents for food.  However, flight puts a limit on how heavy a bird can be, and so how heavy its brain can be.  But flightless birds are a possible candidate.\n\nAmphibians and reptiles are cold-blooded, which seems as though it would rule out our sort of intelligence.  On the other hand, perhaps an intelligent crocodile would think of slowing down when the temperature drops much as we think of sleep.  Remember that a large brain would mean a large egg (and you have to fit the rest of the body inside the egg as well).
542201
A "dot" and a "rag". \nNo, seriously, in most cases animals need to be of the same species (not "family" as a previous answer stated) to be able to produce offspring. However some species of the same genus can mate with each other and produce offspring, such as horses and donkeys, lions and tigers, some smaller cat species, dogs and wolves etc. Mostly the interspecies breed is infertile. This possibility is probably not as unnatural as one think but might rather point out that our (scientists') definition of a species as the basic classification unit of life, still contains elements of artificiality.\nYour mentioned species are not known to interbreed, though.
154701
i've lived in the outback for most of my childhood and never seen any such animals. i say there's no proof and there not here. it would be cool to see one though