Re: What is a Dinosaur ?

[Yutyrannus]

I agree. I, to be honest, have never thought of dinosaurs as reptiles. I think really either birds need to get lumped into reptilia or they and other dinosaurs as well as crocodiles get put into an entirely new group (the better decision in my opinion).

What do you think of them as, then?

Pretty much what I said, I think of archosaurs as another group along with reptiles, mammals, fish, etc.

[tyrantqueen]

I agree. I, to be honest, have never thought of dinosaurs as reptiles. I think really either birds need to get lumped into reptilia or they and other dinosaurs as well as crocodiles get put into an entirely new group (the better decision in my opinion).

What do you think of them as, then?

Pretty much what I said, I think of archosaurs as another group along with reptiles, mammals, fish, etc.

So, you think of them as "ruling reptiles"...

[Yutyrannus]

I agree. I, to be honest, have never thought of dinosaurs as reptiles. I think really either birds need to get lumped into reptilia or they and other dinosaurs as well as crocodiles get put into an entirely new group (the better decision in my opinion).

What do you think of them as, then?

Pretty much what I said, I think of archosaurs as another group along with reptiles, mammals, fish, etc.

So, you think of them as "ruling reptiles"...

I'm not quite sure what you mean, basically I think of dinosaurs and crocodilians as separate in a way from Reptilia. Sorry if that didn't make sense.

[Balaur]

They are giant lizards....hence in the classification of reptiles....of those creatures is also the scientific knowledge that they grow their entire lives, from what we observe with modern reptiles anyways...which is what Science is supposed to be about....observations, and even demonstratable....after all what is the term Dinosaur? The roots of the word are broken down......Dino (Terrible) saur (Lizard). Now someone is changing what the term dinosaur means? This term was invented in 1842 by Sir Richard Owen....
If it has changed, then the word Dinosaur should also be changed into something else to describe them...

But some were giant feathered lizards ..and even warm-blooded.

That doesn't fit the definition of the word reptile :
" a cold-blooded vertebrate of a class that includes snakes, lizards, crocodiles, turtles, and tortoises. They are distinguished by having a dry scaly skin, and typically laying soft-shelled eggs on land. "

I don't think theres enough evidence/proof to say that the giant ones had any feathers or were warm blooded...after all, they are extinct...what do we compare them to?

There's Yutyrannus, the ten meter long feathered tyrannosaur. Also, I believe there was an isotopic analysis on a sauropod tooth that concluded it belonged to a warm-blooded animal. I don't know the exact details though.

[Paleogene Pals]

When I was a kid, dinosaurs were extinct, lumbering reptiles.  Now, they are less lumbering, some very bird-like, and they went un-extinct! MY idea of what is a dinosaur is changing! 

[HD-man]

They are giant lizards....hence in the classification of reptiles....of those creatures is also the scientific knowledge that they grow their entire lives, from what we observe with modern reptiles anyways...which is what Science is supposed to be about....observations, and even demonstratable....after all what is the term Dinosaur? The roots of the word are broken down......Dino (Terrible) saur (Lizard). Now someone is changing what the term dinosaur means? This term was invented in 1842 by Sir Richard Owen....
If it has changed, then the word Dinosaur should also be changed into something else to describe them...

I don't think theres enough evidence/proof to say that the giant ones had any feathers or were warm blooded...after all, they are extinct...what do we compare them to?

No offense, but the above quotes are wrong on several levels (which makes me wonder why only 1 person has tried to correct you on only 1 level).

1stly, dinos ARE NOT "giant lizards": As you can see in the following cladograms, dinos are archosaurian diapsids & lizards are lepidosaurian diapsids; In other words, both are diapsid reptiles, but neither evolved from the other.

2ndly, dinos DID NOT "grow their entire lives": To quote Holtz (See "Dinosaur Growth Rate and Skeletochronology": http://www.geol.umd.edu/~tholtz/G104/lectures/104babies.html ), "Unlike typical non-avian reptiles, dinosaurs seem to have determinate growth: reaching a fully adult size, than stopping growth (or at least slowing it WAY down: all the LAGs bunch up together)."

3rdly, "the term dinosaur" also means "fearfully great reptile" (See "It got lost in the translation": http://reptilis.net/dinosauria/overview.html ).

4thly (in reference to the 1st quote's last sentence), to quote Holtz (See "TAXONOMY": http://www.geol.umd.edu/~tholtz/G104/lectures/104taxon.html ), "But the name can be inaccurate (e.g., "Basilosaurus"--Emperor Reptile--is a whale, not a reptile!) but if the name was formed obeying the rules of taxonomy, that inaccurate descriptor is fine."

5thly (in reference to the 2nd quote), to quote Sampson (See Chapter 11: http://www.doc88.com/p-102817110518.html ), "Although the data supporting elevated metabolic rates in dinosaurs is currently insufficient to demonstrate that they were high-cost, bird- or mammal-like endotherms, this evidence does provide strong support for the notion that dinosaurian metabolic rates were elevated well above those of lizards."

The traditional Class Reptilia was paraphyletic, as it excluded birds and mammals, which are descended from the same common ancestor as the various "reptile" groups.  If you include birds and mammals in the Reptilia, it becomes monophyletic, but is also exactly equivalent to the clade Amniota, and so is redundant.

The upshot is, the traditional Class Reptilia is invalid.  Some taxonomists have proposed a restricted clade Reptilia that would include the nearest common ancestor of Squamata (snakes and other lizards) and Rhynchocephalia (tuataras and many extinct groups) and all its descendants, thus excluding turtles, mammals, and archosaurs (such as crocodilians, dinosaurs, birds, etc.).

Actually, mammals ARE NOT reptiles & Reptilia IS a valid clade (See the following cladograms).

Really helpful; thanks for sharing!

What am I, chopped liver (See my post on page 1 if you don't know what I mean)? Sorta kidding, I know you didn't mean it that way, but still.

[Spinosaurus Aegyptiacus]

Really helpful; thanks for sharing!

What am I, chopped liver (See my post on page 1 if you don't know what I mean)? Sorta kidding, I know you didn't mean it that way, but still.

Lol-of course! Your post was awesome as well; I was trying to say that about all of the previous posters. 

[Newt]

The traditional Class Reptilia was paraphyletic, as it excluded birds and mammals, which are descended from the same common ancestor as the various "reptile" groups.  If you include birds and mammals in the Reptilia, it becomes monophyletic, but is also exactly equivalent to the clade Amniota, and so is redundant.

The upshot is, the traditional Class Reptilia is invalid.  Some taxonomists have proposed a restricted clade Reptilia that would include the nearest common ancestor of Squamata (snakes and other lizards) and Rhynchocephalia (tuataras and many extinct groups) and all its descendants, thus excluding turtles, mammals, and archosaurs (such as crocodilians, dinosaurs, birds, etc.).

Actually, mammals ARE NOT reptiles & Reptilia IS a valid clade (See the following cladograms).

Thanks for the correction.  When I last read on the subject, if I recall correctly, the position of the turtles in relation to the synapsids and diapsids was an unresolved polytomy, with multiple competing trees circulating.  It seems that since then, the diapsid-origin scenario has won out.  That'll teach me to blather without making sure I'm up to date!

Still, it's an important point to remember that the "Reptilia" many of us first learned, which included non-mammalian synapsids (such as the "mammal-like reptiles" and pelycosaurs) and basal amniotes and excluded birds, has changed shape dramatically.

[Hermes888]

One time, a friend of mine called Tyrannosaurus a "giant lizard," and used the literal translation as defense when I called him out on it.

Some of his other "refutations" are here, as direct quotations from an email he sent to me afterwards:
"almost all definitions stated that dinosaurs were creatures coming from a common reptilian or lizard ancestor."
"I feel the term dinosaur isn't a scientific species but a grouping of common creatures from a specific time period."
"dinosaurs have to be for lack of a better word....extinct...or fossilized..."
(please note that for the last one, I did not cut anything out, he has a habit of using ellipses in place of commas)

I feel like this is probably the same "definition" a lot of people think of when faced with the word dinosaur. Essentially, ornithodira, rauisuchia, any and all Mesozoic marine reptiles, and Dimetrodon.
Even though I've seen them referred to as "dinosaurs" plenty of times, I'll exclude coelacanths from the list.

[Ridureyu]

What is a dinosaur?

Baby don't hurt me.  Don't hurt me, no more.

[tyrantqueen]

What is a dinosaur?

A miserable little pile of secrets. But enough talk... Have at you!

[Splonkadumpocus]

What is a dinosaur?

A miserable little pile of secrets. But enough talk... Have at you!

Dinosaur: *eats Dracula*