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Were dinosaurs reptiles? Are birds reptiles?

 
 
Reply Thu 25 May, 2006 03:35 pm
Another thread led to the question of whether dinosaurs were reptiles. I didn't think so because I have come to believe that some dinosaurs were warm blooded, which I *thought* made them a non-reptile. And of course I assumed birds were not reptiles for the same reason. Then I found this, on a reputable site:

Quote:
Reptilia, presented as a Class in our classification, includes turtles (Testudines), snakes and lizards (Lepidosauria), crocodiles and their relatives (Crocodilia), and birds (Aves), as well as a number of extinct groups. Reptiles (including birds!) are amniotes; that is, their eggs are protected from dessication and other environmental problems by an extra membrane, the amnion, not found in the first terrestrial vertebrates (amphibians). Mammals (Mammalia) are also amniotes, but they differ from reptiles in the structure of their skulls (especially the regions associated with chewing and hearing). Mammals also have hair and feed their young with milk produced by modified skin glands (mammary glands).


Source

Are dinosaurs and birds still considered to be reptiles (by virtue of skull structure), even though they are warm blooded?

I thought dinosaurs and mammals and reptiles all had common ancestors, but I didn't know that all dinosaurs evolved from reptiles.
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Type: Discussion • Score: 3 • Views: 31,252 • Replies: 32
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sozobe
 
  1  
Reply Thu 25 May, 2006 03:41 pm
I'm surprised, too. Searched for "are dinosaurs reptiles?" and got:

Quote:
> Are dinosaurs reptiles?
> Yes one of those simple questions that I have a hard time answering without
> boring the heck out of everyone. So, I thought I'd leave it up to the
> experts, who have probably answered this question to droves of school children
> in simple language. The kind of simple language that would be good for a TV
> special aimed at a very general audience. Sometimes knowing a lot about a
> subject makes the simplest question difficult. And I thought I'd never need
> that "Handy Answers" book...shame,shame,shame.

Answer: yes

Old System of Classification (Linnaean): Reptilia includes all
land-dwelling vertebrates which lay eggs with shells except for birds
(Aves) and mammals (Mammalia).

New System (cladistic/phylogenetic): Reptilia includes the most recent
common ancestor of turtles, crocodiles, snakes, lizards, and tuataras,
plus all of that ancestor's descendants. Dinosauria is a subset of this
(and Aves a subset of Dinosauria -- hence Aves is part of Reptilia, too).

I think Bakker's Linnaean classification might be the only one that
excluded Dinosauria from Reptilia.


http://dml.cmnh.org/2000Apr/msg00382.html
0 Replies
 
rosborne979
 
  1  
Reply Thu 25 May, 2006 06:20 pm
sozobe wrote:
I'm surprised, too. Searched for "are dinosaurs reptiles?" and got:


I know. I did the same search, got the same link. I also got a few links which said, "no". So I started searching some of the .edu sites (like the one above), and found that most consider dino's reptiles, and also BIRDS to be reptiles.
0 Replies
 
talk72000
 
  1  
Reply Thu 25 May, 2006 10:00 pm
Dinosaurs evolved from reptiles. The predator-type dinosaurs needing speed to catch their prey became warm-blooded. A biped dinosaurs evolved into birds. Birds are dinosaurs. Chickens can be turned into dinosaurs. The DNA in their beaks contains teeth-forming genes. Scientists can alter the beak DNA to develop teeth in their beaks.
0 Replies
 
talk72000
 
  1  
Reply Thu 25 May, 2006 10:06 pm
Here is a website on Dinosaurs:
Everything you want to know about Dinosaurs.


Dinosaurs
0 Replies
 
xingu
 
  1  
Reply Fri 26 May, 2006 05:34 am
talk wrote:
The DNA in their beaks contains teeth-forming genes. Scientists can alter the beak DNA to develop teeth in their beaks.


Hens teeth. Heard they were rare Laughing
0 Replies
 
coluber2001
 
  1  
Reply Fri 26 May, 2006 01:31 pm
All birds are oviparous--egg laying. Many reptiles are viviparous--live bearing. But some reptiles, including the shingle-backed skink--Trachydosaurus rugosa --and the red-sided garter snake--Thamnophis sirtalis ssp--have to shown to have primitave placentas. There may be many placental reptiles, and only future research will prove it.

I know that at least some dinosaurs were egg laying. Were any viviparous? Some arguments suggest that dinosaurs were warm blooded. So it seems that birds are descended from dinosaurs and not reptiles.
0 Replies
 
yitwail
 
  1  
Reply Fri 26 May, 2006 05:42 pm
i did quite a bit of web browsing on this topic. mammals are synapsids, reptiles are anapsids or diapsids--there's one other type of reptile that included icthyosaurs, i think, but they're all extinct. dinosaurs, birds, snakes, and lizards are diapsids, but turtles are anapsids.

dimetrodon is maybe the best-known fossil synapsid. they were once described as "mammal-like reptiles" but now they're just non-reptile amniotes, i guess.

http://www.ccsf.cc.ca.us/Departments/History_of_Time_and_Life/images/FoyerDisplayA.jpg

the fossil records for both reptiles & synapsids go back to about 310 or 320 million years, at the Joggins area of Nova Scotia. either they had a common ancestor, in which case they're all reptiles, or they evolved separately from amphibians. if i learn anything more, i'll post, but it's a lot of data to wade thru.

[update] i've come across a candidate for the earliest amniote, and hence ancestor to mammals, reptiles, or both--casineria--which preceded synapsids & anapsids by 20 million years. here's a tiny image of a hand, with five digits, only one of which is complete:

http://www.sciencenews.org/pages/sn_arc99/5_22_99/bob1b.jpg

and here's a link to an article about it. since the fossil lacks a skull, it could have been synapsid, diapsid, or neither:

http://www.sciencenews.org/pages/sn_arc99/5_22_99/bob1.htm
0 Replies
 
oralloy
 
  1  
Reply Sat 3 Jun, 2006 05:21 pm
Re: Were dinosaurs reptiles? Are birds reptiles?
rosborne979 wrote:
Another thread led to the question of whether dinosaurs were reptiles. I didn't think so because I have come to believe that some dinosaurs were warm blooded, which I *thought* made them a non-reptile. And of course I assumed birds were not reptiles for the same reason. Then I found this, on a reputable site:

Quote:
Reptilia, presented as a Class in our classification, includes turtles (Testudines), snakes and lizards (Lepidosauria), crocodiles and their relatives (Crocodilia), and birds (Aves), as well as a number of extinct groups. Reptiles (including birds!) are amniotes; that is, their eggs are protected from dessication and other environmental problems by an extra membrane, the amnion, not found in the first terrestrial vertebrates (amphibians). Mammals (Mammalia) are also amniotes, but they differ from reptiles in the structure of their skulls (especially the regions associated with chewing and hearing). Mammals also have hair and feed their young with milk produced by modified skin glands (mammary glands).


Source

Are dinosaurs and birds still considered to be reptiles (by virtue of skull structure), even though they are warm blooded?

I thought dinosaurs and mammals and reptiles all had common ancestors, but I didn't know that all dinosaurs evolved from reptiles.



All dinosaurs evolved from reptiles.

"Reptile/dinosaur/bird" is all part of the same line of evolution.

The term reptile can be used to refer to either the first evolutionary step in that line, or to the entire line, with equal validity.
0 Replies
 
oralloy
 
  1  
Reply Sat 3 Jun, 2006 05:27 pm
talk72000 wrote:
Dinosaurs evolved from reptiles. The predator-type dinosaurs needing speed to catch their prey became warm-blooded. A biped dinosaurs evolved into birds. Birds are dinosaurs. Chickens can be turned into dinosaurs. The DNA in their beaks contains teeth-forming genes. Scientists can alter the beak DNA to develop teeth in their beaks.


Not only are birds a class of dinosaur, I would go so far as to say that certain famous dinosaurs (T-rex and velociraptor) should be considered a type of bird.

They are quite closely related.
0 Replies
 
oralloy
 
  1  
Reply Sat 3 Jun, 2006 05:48 pm
yitwail wrote:
dimetrodon is maybe the best-known fossil synapsid. they were once described as "mammal-like reptiles" but now they're just non-reptile amniotes, i guess.


They are called pelycosaurs.

The evolutionary line "pelycosaur/therapsid/mammal" could be said to be parallel to the line "reptile/dinosaur/bird" (though they didn't happen in the same timescale).

I frequently refer to pelycosaurs and therapsids as "proto-mammals", just because I think it gets the point across to most readers.

I can't stand the term "mammal-like reptiles". I evolved from pelycosaurs and therapsids -- there're no reptiles in my lineage.



yitwail wrote:
the fossil records for both reptiles & synapsids go back to about 310 or 320 million years, at the Joggins area of Nova Scotia. either they had a common ancestor, in which case they're all reptiles, or they evolved separately from amphibians. if i learn anything more, i'll post, but it's a lot of data to wade thru.


We do have common ancestors with reptiles, but synapsids are not reptiles. Our lines diverged before reptiles evolved.
0 Replies
 
rosborne979
 
  1  
Reply Sat 3 Jun, 2006 07:04 pm
oralloy wrote:
We do have common ancestors with reptiles, but synapsids are not reptiles. Our lines diverged before reptiles evolved.


That's interesting.

Did both lines evolve from amphibians?

If birds can be called reptiles because they evolved from them, then why aren't we all called amphibians because we evolved from them?
0 Replies
 
oralloy
 
  1  
Reply Sat 3 Jun, 2006 07:28 pm
rosborne979 wrote:
oralloy wrote:
We do have common ancestors with reptiles, but synapsids are not reptiles. Our lines diverged before reptiles evolved.


That's interesting.

Did both lines evolve from amphibians?


In a way. They weren't the same amphibians that we see today, but I guess it would be fair to call them amphibians.

The first to evolve away from the amphibian path were the reptiliomorphs.

These branched out into the amniotes and several other lines that went extinct.

The amniotes then split into the sauropsids (reptiles/dinosaurs/birds) and the synapsids (pelycosaurs/therapsids/mammals).



rosborne979 wrote:
If birds can be called reptiles because they evolved from them, then why aren't we all called amphibians because we evolved from them?


The same school of thought that calls birds reptiles, does call us all amphibians.

It also says we are all lobe-finned fish.
0 Replies
 
rosborne979
 
  1  
Reply Mon 30 Jun, 2008 04:50 pm
oralloy wrote:
We do have common ancestors with reptiles, but synapsids are not reptiles. Our lines diverged before reptiles evolved.

What is the common ancestor we share with reptiles?

Does a fossil of the creature exist?
0 Replies
 
spendius
 
  1  
Reply Mon 30 Jun, 2008 06:00 pm
Bullshit.

Dinosaurs are dinosaurs, reptiles are reptiles and birds are birds.

What could be easier than that?

Do you not understand Wittgenstein?
0 Replies
 
edgarblythe
 
  1  
Reply Mon 30 Jun, 2008 07:15 pm
spendius wrote:
Bullshit.

Dinosaurs are dinosaurs, reptiles are reptiles and birds are birds.

What could be easier than that?

Do you not understand Wittgenstein?


Good old spendius, come to **** on a good thread.
0 Replies
 
spendius
 
  1  
Reply Wed 2 Jul, 2008 06:16 pm
Look Ed--I think word games are for fun and you shouldn't get paid for playing them.

You should only get paid for contributing something useful to the community such as brewing beer, shifting the **** outasight and dressing the ladies up to look unevolutiony.

You should pay to play word games.
0 Replies
 
oralloy
 
  1  
Reply Wed 2 Jul, 2008 07:22 pm
rosborne979 wrote:
oralloy wrote:
We do have common ancestors with reptiles, but synapsids are not reptiles. Our lines diverged before reptiles evolved.

What is the common ancestor we share with reptiles?


I think it would have been an amphibian of some sort.



rosborne979 wrote:
Does a fossil of the creature exist?


I don't think so, but every now and then I hear on the news that someone has found a fossil of something "close" to the last common ancestor.
0 Replies
 
oralloy
 
  1  
Reply Wed 2 Jul, 2008 07:28 pm
spendius wrote:
Dinosaurs are dinosaurs, reptiles are reptiles and birds are birds.


A dinosaur is a type of reptile and a bird is a type of dinosaur.

Just like an ape is a type of mammal and a hominid is a type of ape.
0 Replies
 
rosborne979
 
  1  
Reply Wed 2 Jul, 2008 09:16 pm
oralloy wrote:
spendius wrote:
Dinosaurs are dinosaurs, reptiles are reptiles and birds are birds.


A dinosaur is a type of reptile and a bird is a type of dinosaur.

Just like an ape is a type of mammal and a hominid is a type of ape.

And Spendi is a type of troll.
 

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