Dinosaurs descended from a primitive archosaurian reptile. they are more advanced than turtles, lizards and snakes and so they are not considered the ancestor of living reptiles. Archosaurian reptiles are more advanced than lizards. Crocodiles and alligators are also archosaurian reptiles. The tuatara, lizards and...
Best answer: Dinosaurs descended from a primitive archosaurian reptile. they are more advanced than turtles, lizards and snakes and so they are not considered the ancestor of living reptiles. Archosaurian reptiles are more advanced than lizards. Crocodiles and alligators are also archosaurian reptiles. The tuatara, lizards and snakes are known as lepidosaurian reptiles. They are close relatives of archosaurian reptiles but more primitive. In fact, archosaurian reptiles probably evolved from a relative of lizards. Turtles are considered anapsid reptiles by most scientists. Anapsids are the most primitive reptiles, the first ones that ever evolved, from an amphibian. All other reptiles, including the archosaurs, lepidosaurs and the reptilian ancestor of mammals (the extinct synapsid reptiles) evolved from anapsids. Nevertheless there are a small number of scientists who claim that turtles are actually closely related to dinosaurs and crocodilies and alligator than they are to lizards. Their evidence for such a relationship, however, is unconvincing.
The ancestry of birds is still a hotly debated subject. However, all scientists agree that birds evolved from an archosurian reptile. What they disagree is whether the bird ancestor is a primitive archosaurian reptile or an advanced one such as a dinosaur. Those who believe that birds evolved from a dinosaur have a bunch of problems that they conveniently overlook. These problems are:
1. identity of the fingers. scientific evidence suggests that birds have fingers 2-3-4, but bird-like dinosaurs have fingers 1-2-3. That means a dinosaur with fingers 1-2-3 simply cannot be ancestral to birds, but people who believe that birds evolved from a dinosaur simply ignore this evidence or else they come up with an unlikely explanation, known as frame shift, to explain how a dinosaur with fingers 1-2-3 can have fingers that look like fingers 2-3-4.
2. temporal paradox. there is no bird-like dinosaur that lived before the first known birds. since ancestors cannot live later than their supposed descendants, this paradox or problem cannot be solved unless someone finds a bird-like dinosaur that lived earlier than the first known birds. In fact, some dinosaur experts have suggested that dinosaurs actually evolved from a bird instead of vice versa to take into account of this problem.
3. Longisquama insignis. This reptile lived some 70 million years earlier than the earliest known birds, and many reputable scientists published a paper showing that it has feathers with detailed anatomical similarities to avian feathers. The '''protofeathers" found on the outline of some dinosaurs such as Sinosauropteryx lack the same detailed anatomical similarities and are most likely collagen fibers, not protofeathers. That means Longisquama is more likely to be the ancestor of birds than any dinosaur, since it lived earlier than birds and it has feathers, something only birds have. Most scientists who insist that birds evolved from a dinosaur simply ignore this fossil or they deny the fact that it has feathers. Some dogmatists even suggest that its huge feathers were not used for gliding but for "display" only. It is simply ludicrous for a small animal to evolve feathers that are about half of the length of its body and not use them to glide and use them just to show off to other animals, some of them may be predators that would love to make a meal out of it. It is like evolving something that says "come and get me for dinner" that cannot be used for gliding. Totally ludicrous but fairly typical of what people who think that birds evolved from a dinosaur will believe.
4. biophysical implausibility of flight from the ground up. Biophysicists suggest that evolving flight from the ground up is highly unlikely and that dinosaurs simply lack the strong shoulder bones and muscles that can allow them to take off from the ground. Even modern birds cannot take off flying from the ground if their supracoracoideus muscles are disabled by severing the tendon. Since dinosaurs are even heavier than the heaviest modern birds and since they lack this muscle, there is really no way for a dinosaur to evolve the ability to fly. The ancestor of birds therefore is most likely to be a small arboreal reptile that glided. Longisquama insignis fits the profile of the bird ancestor a lot better because it is a small arboreal reptile that glided.
The reason most biologists still believe that birds evolved from a dinosaur is because when they went to school to learn biology, most of them were taught that birds evolved from a dinosaur. Since then most biologists have simply not kept up with the current literature about the origin of birds. A number of very important discoveries were made in the past 2 decades, and one should not expect a biologist who works with marine mammals, or plants, or modern reptiles to keep track of these new discoveries. Most biologists are not ornithologists (scientists who study birds) and in fact most ornithologists do not accept the claim that birds evolved from a dinosaur. Those who have unshakable faith that birds evolved from a dinosaur have also shown that they cannot distinguish birds such as Archaeopteryx, Anchiornis, Microraptor, Caudipteryx, Prpotarcheopteryx and Scansoriopteryx from dinosaurs. In fact, they claim that these birds are actually feathered dinosaurs! That is similar to the blind leading the blind. If a scientist cannot tell a bird from a dinosaur, then what good is their dogma that claims birds can only have evolved from a dinosaur?
5 days ago