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Are Dinosaurs Reptiles ?
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Some paleontologists claim that the bird evolved from dinosaurs while still others claim that birds are dinosaurs. One thing for certain is that birds are not reptiles. So, should warm-blooded dinosaurs be classified as reptiles ?
 (06-20-2015, 06:38 PM)'brotherbear' Wrote: Some paleontologists claim that the bird evolved from dinosaurs while still others claim that birds are dinosaurs. One thing for certain is that birds are not reptiles. So, should warm-blooded dinosaurs be classified as reptiles ? Aren't all reptiles cold blooded? If thats the classification for reptile, than I guess they aren't. But I really don't konw.
Some "experts" consider birds as dinosaurs. Birds are not reptiles. Some dinosaurs, at least in the lineage of the coelurosaurs had feathers. Reptiles do not have feathers.
 (06-20-2015, 11:38 PM)Pckts Wrote:brotherbear\ dateline='\'1434807524' Wrote: Some paleontologists claim that the bird evolved from dinosaurs while still others claim that birds are dinosaurs. One thing for certain is that birds are not reptiles. So, should warm-blooded dinosaurs be classified as reptiles ? The only exception for a reptile to be warm-blooded is to be a "mammal-like reptile" or therapsid. I'm not sure if therapsids possessed fur with reptile-like scaly skin, or had softer skin and no fur. If you look very close at human skin, you can see bare and soft scales, a remnant of our synapsid ancestors. I think dinosaurs were both warm and cold-blooded depending on how far you go back in their evolution/lineage.
http://www.dinosaurjungle.com/prehistori...ptiles.php
Amniotes (tetrapod vertebrate animals with a terrestrially adapted eggs) are traditionally divided into three categories:
Neither would I consider the so-called "mammal-like reptiles" to be true reptiles; nor the pterodactyls.
(01-23-2016, 12:46 AM)Polar Wrote:(01-23-2016, 12:42 AM)brotherbear Wrote: Neither would I consider the so-called "mammal-like reptiles" to be true reptiles; nor the pterodactyls. They have no living relatives, so a lot of guesswork. It takes energy to fly, so likely warm-blooded. There is also evidence of fur. I believe that they were in a class of their own; evolved from reptiles but neither reptile nor bird nor mammal.
Quite astonishing, then. The first discovered bird-like dinosaur (not the first bird-like dinosaur in existence), Archaeopteryx, had feathers and a bird-like beak, but what about its skin? Did it have softer and moist skin like that of modern birds, or did it have rough and scaly skin like that of dinosaurs?
We believed that dinosaurs were reptile. But now they no longer are. Because, yes, reptiles are not hot blooded animals with feathers and so on. Otherwise we have to modify, to alter, the reptile definition.
I think Archaeopteryx was a first attempt from the dinosaur lineage in order to become a winged animal with feathers. But it wasn't a success.  
Like Therapsids, Dinosaurs are transitional between true reptiles and their modern relatives (In this case birds and mammals).
Reptiles in them selves are not really as close as some may think. There is a lot of grey area. For example, lizards are actually more closely related to snakes then they are to turtles or crocodiles. Crocodiles on the other hand believe it or not are actually more closely related to Birds then they are to Snakes. Both crocodiles and snakes are classified as reptiles, yet they aren't as closely related to each other as they are to other types of animals.  *This image is copyright of its original author https://news.ucsc.edu/2014/12/crocodile-genomes.html  (03-30-2020, 05:04 AM)Kingtheropod Wrote: Reptiles in them selves are not really as close as some may think. There is a lot of grey area. For example, lizards are actually more closely related to snakes then they are to turtles or crocodiles. Crocodiles on the other hand believe it or not are actually more closely related to Birds then they are to Snakes. Both crocodiles and snakes are classified as reptiles, yet they aren't as closely related to each other as they are to other types of animals.Thank you for saying about that grey area! I once wondered about the positioning of that 1st green split & did some research... Fascinating stuff. Turns out there is actually good chance that Mammalia originated from amphibians, or amphibian like species of earliest reptiles. The pre-mammals evolved directly alongside Reptilia. Dimetrodon was more related to mammals than reptiles, belonged to a group called "Non Mammalian Synapsids" or "Mammal Like Reptiles" (distinction was indeed much blurred back then). Later Synapsids/Therapids or mamalian reptiles were closest related to it. From them the first proper mammal came in early Cretaceous 50-75 million years before the first avian birds, basically direct descendants of theropods, a lineage of dinosaurs.  *This image is copyright of its original author
In my personal opinion, they are like the intermediate between reptiles, birds and mammals. Dinosaurs are pretty unique.
(03-30-2020, 08:49 AM)johnny rex Wrote: In my personal opinion, they are like the intermediate between reptiles, birds and mammals. Dinosaurs are pretty unique.That's way too much oversimplification. Not too accurate either. We don't know enough to form much of an opinion (you can't even call birds "fluffy warmblooded dinos" anymore). Very often people dont understand the variation within kingdoms well, & the blurred lines between them even less so. Many find birds actually being very close to reptiles, close enough to be a branch of it, to be mindblowing & borderline overstated. @Kingtheropod's post is covers just a mere part of the whole spectrum. It's all a very messed jumble.  *This image is copyright of its original author Feathers are modified scales, and many dinosaurs had feathers. Some didn’t. Look at birds — they have scales on their legs and feet, just like all reptiles. They lay eggs, just like most reptiles. And their teeth, when scientists switch on the gene to grow them, are non-differentiated, just like all reptiles. Lots of dinosaurs had beaks, too. So do turtles. (https://www.quora.com/If-the-T-Rex-is-mo...a-dinosaur) Consider this; Crocodiles and Alligators are more closely related to birds than they are other species of reptiles, like lizards or snakes. Now this. There are fish closer related to us humans, than some other fish. Warm blooded thermo-regulating body isn't any recent development between Synapsids/Therapids (they're NOT dinosaurs, just like they aren't crocodilians or lizards) either. Opah: Warm-Blooded Fish Found. It didn't become prominent in those levels because it wasn't much of an evolutionary advantage among them. |
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