If birds are dinosaurs then what are dinosaurs?

So funny story T-rex meat would probably be poisonous to you or me. Cadmium levels in the environment were a lot higher in the late Cretaceous and Rexy being an high on the food chain predator would probably have toxic levels in his flesh.
 
JoeMorgue said:
Okay but let's ask the real question.

If I'm ordering an Apatosaurus prime rib at a restaurant would it be steak or fowl? Do I get White Wine or Red Wine to go with it?
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Are you Fred or Barney?

Planigale said:
If it is the white meat, the white wine if it is the dark meat red wine.

When were you brought up?
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Hmmm... tastes like chicken!
 
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Ziggurat said:
Tetrapods. Dinosaurs are tetrapods.
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Alright then. We're getting somewhere. People are going to want to know what a tetrapod looks like. What do we tell them? They especially want to know if tetrapods are bad ass killers.
 
The only bird that shows mercy upon its prey is the vulture. Well, it's already dead and this won't hurt it any.
 
Lobe finned fish. Dinosaurs are lobe finned fish. So are snakes. And people.
 
William Parcher said:
Alright then. We're getting somewhere. People are going to want to know what a tetrapod looks like. What do we tell them? They especially want to know if tetrapods are bad ass killers.
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Lobe-finned fishes
The group Tetrapoda, a superclass including amphibians, reptiles (including dinosaurs and therefore birds), and mammals, evolved from certain sarcopterygians; under a cladistic view, tetrapods are themselves considered a group within Sarcopterygii.
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I've been amused for some time that dinosaurs are broadly divided into Saurichia (lizard hipped) and Ornithischia (bird hipped); and that birds are descended from the former.
 
theprestige said:
We're still kind of shocked by the idea that chickens are the heirs of the thunder lizards of prehistory.
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Ahem. *nerd snort* Technically, "thunder lizard" is the translation of the word brontosaurus. Birds aren't descended from brontosaurus. The words you're looking for are "terrible lizard".

William Parcher said:
Alright then. We're getting somewhere. People are going to want to know what a tetrapod looks like. What do we tell them? They especially want to know if tetrapods are bad ass killers.
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The word "tetrapod" literally means "four limbs". What does one look like? Everything that has four limbs is a tetrapod. Some of them are bad ass killers, some of them are fluffy bunnies.
 
JoeMorgue said:
This is also why the nitpicking "Pterosaurs and aquatic mammals aren't dinosaurs!" thing is kind of annoying to me, as if "Dinosaur" is some super-specific scientific term.
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Well, it is. Dinosaurs are specifically defined as terrestrial vertebrates. That means that they're not flyers, and they're not swimmers. Ichthyosaurs and pterosaurs are not dinosaurs. They're distinct groups of animals that just happened to be around at the same time.

Trebuchet said:
I've been amused for some time that dinosaurs are broadly divided into Saurichia (lizard hipped) and Ornithischia (bird hipped); and that birds are descended from the former.
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That division is no longer recognised as fundamental. There are too many exceptions.

Basically everything that I learned from the dinosaur books I loved as a child in the 70s is wrong.
 
I've consulted the only dinosaur expert I know, which is my 7-year-old nephew. Posing the OP's question to him, he replied "Dinosaurs are the most awesome thing in like the whole world and history!"

So there you have it.
 
William Parcher said:
The idea is that birds are what they descended from and therefore are dinosaurs. So then dinosaurs too are whatever they descended from.

Surprise ... birds are dinosaurs and dinosaurs are what? If we are clever and accurate to say that birds are dinosaurs then what should we say that dinosaurs are in order to use that same logic with consistency?
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A clade is just a group and all it's descendants. So if two things are members of a clade, then so are their common ancestors. If Chimpanzees and Gorillas are both apes, then so are the common ancestor of Chimps and Gorillas. And so, necessarily, are any other descendants of that common ancestor (including humans). So either humans are apes or "apes" isn't a word that describes a clade, it's describing something else.

For instance Fish clearly doesn't describe a clade, because if it does then it includes whales (and humans), as both are more closely related to some fish than those fish are to other fish.

From an evolutionary perspective clades are a pretty useful classification system, because they're based on relatedness. If dinosaurs are a clade, then birds are dinosaurs. But there are other classifications that can be useful other than cladistic ones. I think fish is still a useful category, even if it doesn't include humans. It's useful because animals that adapted to life in the ocean over deep time have some shared characteristics, and perhaps more importantly life that moved on to land changed in meaningful ways such that a classification of "fish that stayed in the ocean" actually does capture something important.

But is dinosaurs like that? I'm not sure. Birds are a clade of their own, it's entirely possible to talk about birds as birds (one branch of the dinosaur family). Generally I think a cladistic approach makes the most sense here. Birds are dinosaurs, even though not all dinosaurs are* birds.

*Probably should be "were", since at the moment all dinosaurs are birds. :boxedin:
 
arthwollipot said:
Well, it is. Dinosaurs are specifically defined as terrestrial vertebrates. That means that they're not flyers, and they're not swimmers..
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Dinosauria are defined as the last common ancestor of Triceratops horridus, Passer domesticus and Diplodocus carnegii, and all of its descendants.

Some birds are flyers. All birds are dinosaurs. Therefore some dinosaurs are flyers. Similarly for swimmers.

Even for non-avian dinosaurs, their terrestriality is an observation, not part of the definition.
 
This thread reminded me about that paper a few years ago, where they turned a chicken into a t-rex by putting a plunger on its butt:
 
Checkmite said:
I've consulted the only dinosaur expert I know, which is my 7-year-old nephew. Posing the OP's question to him, he replied "Dinosaurs are the most awesome thing in like the whole world and history!"

So there you have it.
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This is what I love about this place. Lots of knowledgeable lay people make some clear responses that really helps to lay the groundwork around an issue. And the we get input from a true expert that puts it all into context.

Thank you.
 
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