History UsefulNotes / Dinosaurs

14th Oct '15 1:34:52 PM TrollMan
Is there an issue? Send a Message
Dinosaurs are close cousins to the crocodilians, both being archosaurs; they share many traits, such as alveolate teeth, solid skulls, diapsid openings, and a bipedal posture, though this was later replaced with a semi-erect gait in crocodilians. It may appear odd, but modern crocodilians descended from bipedal, dinosaur-looking ancestors which returned to a four-legged body plan after their adaptation to water. This kind of back-and-forth evolving is quite common in nature, with cetaceans, ostriches, seals, flightless beetles and turtles being good examples of animals that evolved out of one adaptation and then evolved back into it again. Birds, considered as a distinct class of vertebrate in traditional systematics, are actually theropod dinosaurs, a hypothesis already proposed in the nineteenth century after the discovery of the famous ''[[UsefulNotes/StockDinosaursTrueDinosaurs Archaeopteryx]]'' (an animal with dinosaurian skeleton ''and'' feathered wings and tail) but rejected by most scientists for a long amount of time. The link between dinosaurs and birds through ''Archaeopteryx'' was resurrected again in the 1960s, and has been definitively proven only in the 1990's by the long list of feathered dinosaurs and early birds recently found in the fossil record, which show strong anatomical similarities. Impressions of feathers in the fossils make for good evidence, and blend into each other so seamlessly that telling apart bird-like dinosaurs (such as ''[[UsefulNotes/StockDinosaursTrueDinosaurs Velociraptor]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Caudipteryx]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Beipiaosaurus]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Sinosauropteryx]]'') and dino-like birds (''[[UsefulNotes/PrehistoricLifeOtherExtinctCreatures Jeholornis]]'', ''[[UsefulNotes/PrehistoricLifeOtherExtinctCreatures Confuciusornis]]'' and so on) has become very difficult today. Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. The more recently discovered ''[[UsefulNotes/PrehistoricLifeDinosaurs Kulindadromeus]]'' of Siberia has hair-like covering of several varieties, the most advanced of which resemble [[https://upload.wikimedia.org/wikipedia/commons/b/b4/Feather_stages_diagram.svg type-3 theropod feathers]], strengthening the idea that feathers are basal to dinosaurs.
to:
Dinosaurs are close cousins to the crocodilians, both being archosaurs; they share many traits, such as alveolate teeth, solid skulls, diapsid openings, and a bipedal posture, though this was later replaced with a semi-erect gait in crocodilians. It may appear odd, but modern crocodilians descended from bipedal, dinosaur-looking dinosaur-looking, endothermic (warm-blooded) ancestors which returned to a four-legged four-legged, ectothermic (cold-blooded) body plan after their adaptation to water. This kind of back-and-forth evolving is quite common in nature, with cetaceans, ostriches, seals, flightless beetles and turtles being good examples of animals that evolved out of one adaptation and then evolved back into it again. again. Turtles might be next closest living relative of dinosaurs (although distant), but the placement of turtles among the reptile tree of life is ongoing and controversial. Birds, considered as a distinct class of vertebrate in traditional systematics, are actually theropod dinosaurs, a hypothesis already proposed in the nineteenth century after the discovery of the famous ''[[UsefulNotes/StockDinosaursTrueDinosaurs Archaeopteryx]]'' (an animal with dinosaurian skeleton ''and'' feathered wings and tail) but rejected by most scientists for a long amount of time. During this time birds were thought to have descended from "thecodonts" (a now rejected grouping of Triassic reptiles) and any similarities between birds and dinosaurs was a product of convergent evolution. The link between dinosaurs and birds through ''Archaeopteryx'' was resurrected again in the 1960s, and has been definitively proven only in the 1990's 1990s by the long list of feathered dinosaurs and early birds recently found in the fossil record, which show strong anatomical similarities. Impressions of feathers in the fossils make for good evidence, and blend into each other so seamlessly that telling apart bird-like dinosaurs (such as ''[[UsefulNotes/StockDinosaursTrueDinosaurs Velociraptor]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Caudipteryx]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Beipiaosaurus]]'', ''[[UsefulNotes/PrehistoricLifeDinosaurs Sinosauropteryx]]'') and dino-like birds (''[[UsefulNotes/PrehistoricLifeOtherExtinctCreatures Jeholornis]]'', ''[[UsefulNotes/PrehistoricLifeOtherExtinctCreatures Confuciusornis]]'' and so on) has become very difficult today. today. Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. The more recently discovered ''[[UsefulNotes/PrehistoricLifeDinosaurs Kulindadromeus]]'' of Siberia has hair-like covering of several varieties, the most advanced of which resemble [[https://upload.wikimedia.org/wikipedia/commons/b/b4/Feather_stages_diagram.svg type-3 stage-3 theropod feathers]], strengthening the idea that feathers are basal to dinosaurs. dinosaurs.
14th Oct '15 1:13:51 PM TrollMan
Is there an issue? Send a Message
[[BlatantLies A brief summary]] of [[TropesaurusIndex dinosaurs]], for those of us who wish to address a few problems where ArtisticLicensePaleontology.
to:
[[BlatantLies A very brief summary]] of [[TropesaurusIndex dinosaurs]], for those of us who wish to address a few problems where with ArtisticLicensePaleontology.

There is a tendency in popular culture to identify ''every'' prehistoric reptile as a dinosaur, especially if it is big, nasty-looking, or just plain weird. This gets to the point when the word "dinosaur" is used as a synonym for "prehistoric monster". In the most extreme cases, [[DinosaursAreDragons legendary characters]] are called dinosaurs. Actual dinosaurs, despite being astonishingly diverse in size, shape, and possibly even behaviour, are all restricted to the criteria mentioned below. Thus, pterosaurs (flying reptiles) and the sea-living Mesozoic reptiles, the ichthyosaurs, plesiosaurs, and mosasaurs, are not dinosaurs at all (mosasaurs are actually closer to ''varanids'' (monitor lizards) than they are to any dinosaur) Furthermore, dinosaurs always walked with their limbs tucked under their bodies and upright, just like humans, ostriches and elephants, and very unlike modern reptiles. Finally, if ''[[UsefulNotes/StockDinosaursNonDinosaurs Dimetrodon]]'' is ever described anywhere as a dinosaur, you have a right to get angry; not only was it a sail-backed synapsid (the group including mammals and their extinct kin) and more closely related to the mammals than to dinosaurs, but it lived at completely the wrong time. Most dinosaurs lived in the Mesozoic Era, (251-65 million years ago). ''Dimetrodon'' lived in the Permian period, (295-251 million years ago), when the dinosaurs hadn't even evolved yet.
to:
There is a tendency in popular culture to identify ''every'' prehistoric reptile reptile, or even animal, as a dinosaur, especially if it is big, nasty-looking, or just plain weird. This gets to the point when the word "dinosaur" is used as a synonym for "prehistoric monster"."[[PrehistoricMonster prehistoric monster]]". In the most extreme cases, [[DinosaursAreDragons legendary characters]] are called dinosaurs. Actual dinosaurs, despite being astonishingly diverse in size, shape, and possibly even behaviour, are all restricted to the criteria mentioned below. Thus, pterosaurs (flying reptiles) "reptiles") and the sea-living Mesozoic reptiles, the ichthyosaurs, plesiosaurs, and mosasaurs, are not dinosaurs at all (mosasaurs are actually closer to ''varanids'' (monitor lizards) monitor lizards and snakes than they are to any dinosaur) Furthermore, dinosaurs always walked with their limbs tucked under their bodies and upright, just like humans, ostriches and elephants, and very unlike modern reptiles. Finally, if ''[[UsefulNotes/StockDinosaursNonDinosaurs Dimetrodon]]'' is ever described anywhere as a dinosaur, you have a right to get angry; not only was it a sail-backed synapsid (the group including mammals and their extinct kin) and more closely related to the mammals (and therefore humans) than to dinosaurs, but it lived at completely the wrong time. Most dinosaurs lived in the Mesozoic Era, (251-65 million years ago). ''Dimetrodon'' lived in the Permian period, (295-251 million years ago), when the dinosaurs hadn't even evolved yet.

* [[http://xkcd.com/1211/ Birds are dinosaurs.]] Because there are still birds alive today, dinosaurs are [[ScienceMarchesOn technically not exinct]]! And ''we eat them'' all the time! Sometimes irony is ''[[LiteralMetaphor literally]]'' delicious.
to:
* [[http://xkcd.com/1211/ Birds are dinosaurs.]] Because there are still birds alive today, dinosaurs are therefore [[ScienceMarchesOn technically not exinct]]! extinct]]! And ''we eat them'' all the time! Sometimes irony is ''[[LiteralMetaphor literally]]'' delicious.

That much most textbooks and children's books will tell you, but the curious thing is that birds are theropod saurischians, not ornithischians, even though you'd expect some sort of bird-like hip arrangement to appear in their ancestors. So how did theropods bring about the bird group if they had the lizard hip, not the bird hip? Fortunately, this is quickly resolved: ornithischians are not the only dinosaurs to have bird-like hips. Many maniraptorans, those theropod dinosaurs which include birds as well as the theropods most closely related to birds (and are therefore what most people refer to when they talk about bird-like dinosaurs), have a bird-like hip arrangement, which appears to be a side effect of some adopting a knee-driven running style, and of others being weird herbivorous theropods. Interestingly, the most basal ornithischians, such as ''[[UsefulNotes/PrehistoricLifeDinosaurs Pisanosaurus]]'', hadn't yet evolved the backwards-pointing pubis. At first, you might think this rather puts a hole through our lovely little classification. How can a saurischian be a saurischian if it's got bird-like hips, a characteristic of ornithischians? One answer is that the pelvis of all members of a group is similar in a variety of details, not merely whether the pubis points forward or back. And luckily, ornithischians can still be kept separate from saurischians by another diagnostic: all ornithischians have a U-shaped protruding bone at the front of the lower jaw called a predentary bone, often ending with a beak, and most of them have a row of chewing teeth lined up either side of the face, giving it a certain "hollow cheek" look like that of a horse. This suggests that many ornithischians chewed their food, unlike saurischians. Also, saurischians have air sacs in the vertebrae that ornithischians lacked, air sacs which the birds inherited, and which help to keep birds lightweight when flying.
to:
That much most textbooks and children's books will tell you, but the curious thing is that birds are theropod saurischians, not ornithischians, even though you'd expect some sort of bird-like hip arrangement to appear in their ancestors. So how did theropods bring about the bird group if they had the lizard hip, not the bird hip? Fortunately, this is quickly resolved: ornithischians are not the only dinosaurs to have bird-like hips. Many maniraptorans, those theropod dinosaurs which include birds as well as the theropods most closely related to birds (and are therefore what most people refer to when they talk about bird-like dinosaurs), have a bird-like hip arrangement, which appears to be a side effect of some adopting a knee-driven running style, and of others being weird herbivorous theropods. Bird-like hips therefore evolved independently in theropods several times. Interestingly, the most basal ornithischians, such as ''[[UsefulNotes/PrehistoricLifeDinosaurs Pisanosaurus]]'', hadn't yet evolved the backwards-pointing pubis. At first, you might think this rather puts a hole through our lovely little classification. How can a saurischian be a saurischian if it's got bird-like hips, a characteristic of ornithischians? One answer is that the pelvis of all members of a group is similar in a variety of details, not merely whether the pubis points forward or back. And luckily, ornithischians can still be kept separate from saurischians by another diagnostic: all ornithischians have a U-shaped protruding bone at the front of the lower jaw called a predentary bone, often ending with a beak, and most of them have a row of chewing teeth lined up either side of the face, giving it a certain "hollow cheek" look like that of a horse. This suggests that many ornithischians chewed their food, unlike saurischians. Also, saurischians have air sacs in the vertebrae that ornithischians lacked, air sacs which the birds inherited, and which help to keep birds lightweight when flying. flying (this is probably a reason why no ornithischian ever reached the size of the largest sauropods).

* Although originally named based on their hip arrangement, the most basal ornithischians still had forward-pointing pubis bones and some very derived saurischians had backwards-pointing pubis bones.
to:
* Although originally named based on their hip arrangement, the most basal ornithischians still had forward-pointing pubis bones and some very derived groups of saurischians had backwards-pointing pubis bones.
14th Oct '15 12:58:54 PM TrollMan
Is there an issue? Send a Message
Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. The more recently discovered ''[[UsefulNotes/PrehistoricLifeDinosaurs Kulindadromeus]]'' of Siberia has hair-like covering of several varieties, the most advanced of which resemble type-3 theropod feathers, strengthening the idea that feathers are
to:
Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. The more recently discovered ''[[UsefulNotes/PrehistoricLifeDinosaurs Kulindadromeus]]'' of Siberia has hair-like covering of several varieties, the most advanced of which resemble [[https://upload.wikimedia.org/wikipedia/commons/b/b4/Feather_stages_diagram.svg type-3 theropod feathers, feathers]], strengthening the idea that feathers are
14th Oct '15 12:57:07 PM TrollMan
Is there an issue? Send a Message
Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. Another ornithschian, this one from Siberia, was reported at the 2013 SVP confrence[[note]]but, much to the disappointment of the paleontology community, the talk was ultimately canceled due to an unfortunate injury sustained by the presenting author[[/note]] and confirmed to sport integument.
to:
Interestingly, some ornithischian dinosaurs like ''[[UsefulNotes/PrehistoricLifeDinosaurs Psittacosaurus]]'' and ''[[UsefulNotes/PrehistoricLifeDinosaurs Tianyulong]]'' have been discovered with quills or other structures that strongly resemble feathers, which has raised intriguing questions about what dinosaurs looked like. Some think all dinosaurs originally had some sort of covering at the start of their evolution; then this covering (perhaps some sort of hypothetical "down") was lost in some lineages, or at least modified into other specialized structures (the quills on ''Psittacosaurus'' or even the dorsal spines on the sauropod ''[[UsefulNotes/StockDinosaursTrueDinosaurs Diplodocus]]'' may have this origin). The fact that the closely-related pterosaurs have a covering made of a sort of hollow hair seems to confirm this hypothesis. All the same, it does not eliminate the chance that the pterosaurs stumbled across the same solution on their own. If so, it would have been an example of convergent evolution. Another ornithschian, this one from Siberia, was reported at The more recently discovered ''[[UsefulNotes/PrehistoricLifeDinosaurs Kulindadromeus]]'' of Siberia has hair-like covering of several varieties, the 2013 SVP confrence[[note]]but, much to most advanced of which resemble type-3 theropod feathers, strengthening the disappointment of the paleontology community, the talk was ultimately canceled due idea that feathers are basal to an unfortunate injury sustained by the presenting author[[/note]] and confirmed to sport integument. dinosaurs.

Many dinosaurs cared for their young in this way - it may have been what contributed to their success during the stable periods of the Mesozoic. Studies of their egg fossils, nests, and infant bones suggest that some dinosaurs, like ''Allosaurus'', started their lives as precocious babies, were guarded by their mothers for a short time, and then left to grow up on their own, often forming herds with other young dinos of their own kind. One particularly heartwarming fossil shows an ''Oviraptor'' mother/father ([[PapaWolf likely the latter]]) roosting on its clutch of eggs, trying to protect them from a sandstorm which overwhelmed and fossilised its last act of parenthood for millions of years. This is all the more heartwarming because it also revealed that the previous suspicion that ''Oviraptor'' were egg-thieves was, in fact, based on a misunderstanding of a previous fossil.
to:
Many dinosaurs cared for their young in this way - it may have been what contributed to their success during the stable periods of the Mesozoic. Studies of their egg fossils, nests, and infant bones suggest that some dinosaurs, like ''Allosaurus'', started their lives as precocious babies, were guarded by their mothers for a short time, and then left to grow up on their own, often forming herds with other young dinos of their own kind. One particularly heartwarming fossil shows an ''Oviraptor'' mother/father ([[PapaWolf more likely the latter]]) roosting on its clutch of eggs, trying to protect them from a sandstorm which overwhelmed and fossilised its last act of parenthood for millions of years. This is all the more heartwarming because it also revealed that the previous suspicion that ''Oviraptor'' were egg-thieves was, in fact, based on a misunderstanding of a previous fossil.
30th Sep '15 6:54:15 AM TrollMan
Is there an issue? Send a Message
Added DiffLines:
** Similarly, dinosaurs that did chew (like hadrosaurs and ceratopsians) didn't chew like mammals did by moving their lower jaw side to side, instead moving the jaws front to back.
11th May '15 4:46:52 AM SeptimusHeap
Is there an issue? Send a Message
-->-- '''SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]]
to:
-->-- '''SymphonyOfScience''', '''WebVideo/SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]]
28th Jan '15 10:16:23 AM Willbyr
Is there an issue? Send a Message
-->''The more we find, the more complete our understanding,''\\
to:
-->''The ->''The more we find, the more complete our understanding,''\\

-->-'''SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]]
to:
-->-'''SymphonyOfScience''', -->-- '''SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]]

Added DiffLines:
-->-'''SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]] [[foldercontrol]]

Added DiffLines:
-->-'''SymphonyOfScience''', [[https://www.youtube.com/watch?v=ige2YBBJeh4 "The World of the Dinosaurs"]]
6th Oct '14 7:20:38 AM laplaneteetlesoleil
Is there an issue? Send a Message
''[[Utterly Main/PrehistoricMonster awe-inspiring]].''\\
to:
''[[Utterly Main/PrehistoricMonster ''[[Main/PrehistoricMonster Utterly awe-inspiring]].''\\
6th Oct '14 7:20:19 AM laplaneteetlesoleil
Is there an issue? Send a Message
''Utterly [[Main/PrehistoricMonster awe-inspiring]].''\\
to:
''Utterly [[Main/PrehistoricMonster ''[[Utterly Main/PrehistoricMonster awe-inspiring]].''\\
2nd Oct '14 7:41:51 AM laplaneteetlesoleil
Is there an issue? Send a Message
''Utterly awe-inspiring.''\\
to:
''Utterly awe-inspiring.[[Main/PrehistoricMonster awe-inspiring]].''\\
This list shows the last 10 events of 80. Show all.