Are Birds reptiles?

[Guest hassiRom]

Hello all,

 

Please help me and a friend solve a long-running argument. One of us is stating simply that birds are reptiles. The other is stating that while they may have both evolved from Dinosaurs, birds are distinctly a seperate group of animals.

 

Please help!!!!!

[-Demosthenes-]

They evolved from reptiles, but they are warm blooded, they are a classification of there own: Birds.

[Guest hassiRom]

Thanks for the reply.

 

Anyone else that may want to share their opinions is invited to. One person will not be able to settle this agreement between us. If you have anything to add, please share it. Im even thinking about visiting our Local Zoo to get the answer from an expert.

[AzurePhoenix]

Dinosaurs evolved from clear reptiles, but themselves possesed several features that brings their reptilian status into question, such as possessing four chambered hearts, and possibly being endothermic (later therapods of certain groups most certainly were). Subsequently, truly endothermic feathered avians evolved from dinosaurs. In my opinion, they are no more reptiles than we are, having ourselves evolved from reptiles.

 

The true answer would largely be based on ever-changing taxanomic criteria. Scientists and sects of scientists are constantly debating and redefining where things belong and why. This site discusses it http://en.wikipedia.org/wiki/Reptile

[Ophiolite]

In my opinion, they are no more reptiles than we are, having ourselves evolved from reptiles.

Remember you are required by law to exclude Mokele from that exclusion.

[AzurePhoenix]

Of course, Mokele is by no way any more a typical example of a mere Homo sapien sapien than I, and his reptilianity is ingrained into his legendary status.

[Mokele]

Awww, I feel so loved!

 

Anyhow, what it boils down to is how to classify things as a whole. Some argue that all organisms with a certain common ancestor (a "clade") must be grouped as one, thus making birds a part of reptilia. Others argue that if one branch of the clade is sufficiently different, then it is justifiable to give it a separate classification (in which case birds would not be reptiles).

 

Of course, this gets even *more* complicated when you take extinct species into account. It's easy to argue that birds are different enough to be separate based on modern animals, but much harder when presented with numerous fossils that seem to be somewhere between bird and dinosaur. Where does one draw the line? Should one draw any line at all, or should it be cladistic (the first of the two approaches I mentioned). Currently cladistics is gaining popularity, but not without controversy.

 

The problem is that taxonomy itself is a junction between science and language, since it was invented as a way to talk about species and groups of species. The former is all about logic, rules, evidence, evolutionary history, etc, while the latter is more fluid, intuitive, arbitrary and immediate. That's not saying one is better, just that the two work in different ways, and how we think is not always how we speak.

 

Basically, cladistics (which says birds are a type of reptile) is more scientifically accurate, but is more cumbersome, difficult to use, and impedes the primary purpose of taxonomy, which is communication. On the other hand, phenetics (which separates birds and reptiles) is more intuitive, easier to communicate, but is often very wrong and fosters misunderstandings which have to be corrected (a process that itself weighs down and impedes communication).

 

So the best answer is that birds evolved from dinosaurs, which evolved from archosaurs, which evolved from reptiles. To what extent which or any of these groups is within class Reptilia is highly dependent upon one's perspective and position.

 

In essence, it's an issue of "how do we draw the lines?", which is complicated by linguistics and the fact that, frankly, the lines are pretty much just arbitrary concepts for our benefit anyway.

 

Mokele

[AzurePhoenix]

So the archosaurs' classification as reptiles is sketchy? (from your sagacious and much beloved viewpoint, not necessarily that of other squabbling scientists)

[Mokele]

Personally, no, I don't think there's a way from either viewpoint to argue archosaurs as separate, since they're just not different enough for phenetics to separate them, and are part of the clade so that cladistics keeps them lumped.

 

Mokele

[the tree]

I wouldn't say that it's a compliated issue at all, to conclude it all you need is elementary logic and a dictionary.

http://dictionary.reference.com/search?q=bird

Any of the class Aves of warm-blooded, egg-laying, feathered vertebrates with forelimbs modified to form wings.

http://dictionary.reference.com/search?q=reptile

Any of various cold-blooded, usually egg-laying vertebrates of the class Reptilia, such as a snake, lizard, crocodile, turtle, or dinosaur, having an external covering of scales or horny plates and breathing by means of lungs.

Therefore one object cannot be both a reptile and a bird at the same time.

(Unless of course it had two circulatory systems, which it doesn't.)

[Mokele]

Try using a *real* reference, and you'll see that things are rarely that simple.

 

Both of your definitions are flawed and worthless, on acount of being from an inferior, non-technical source. I'll explain.

 

Any of the class Aves of warm-blooded, egg-laying, feathered vertebrates with forelimbs modified to form wings.

 

So aren't ostriches or penguins birds? What about Auks?

 

Any of various cold-blooded, usually egg-laying vertebrates of the class Reptilia, such as a snake, lizard, crocodile, turtle, or dinosaur, having an external covering of scales or horny plates and breathing by means of lungs.

 

And what if dinosaurs truly were warm blooded? Would they be birds, then?

 

Therefore one object cannot be both a reptile and a bird at the same time.

 

Then tell me, which was Archaeopteryx?

 

(Unless of course it had two circulatory systems, which it doesn't.)

 

1) "Warm blooded" or "cold blooded" has got nothing to do with the blood. It has to do with body temperature, basal metabolism, and hormonal controls. The technical terms are "endothermic" and "ectothermic" (or "homeothermic" and "heterothermic").

 

2) So, what's an opossum? Sure, it's usually got a high body temperature, but that temperature *does* fluctate slightly based on environment. It also hibernates, during which time it's body temperature drops to ambient and it becomes effectively "cold blooded", to use the vernacular.

 

----------------

 

You cannot simply pull definitions out of your cloaca and say "there, that's it!", because those definitions are meaningless without some sort of support. What I'm talking about is how we actually get those definitions, the overal schemes for how we classify all life.

 

Plus, as Sayanora says, "For the love of Jebus, Dictionary.com is not a technical resource."

 

Mokele

[AzurePhoenix]

Therefore one object cannot be both a reptile and a bird at the same time.

The problem is that people are looking for clearcut definitions that will apply to every frickin critter. Evolution doesn't care about your damn taxonomic trees!!!!! One creature gradually becomes another!!! There's going to be overlapping!!!

 

This dinosaur developed an avian-hip structure, but lacks feathers, this one's forelimbs are similar in form to a bird's wings, but it's cearly not a bird, this small dinosaur has feathers and wings, but also has teeth ad a long tail... etc, etc, etc

 

Any of the class Aves of warm-blooded, egg-laying, feathered vertebrates with forelimbs modified to form wings.

Arguably, certain dinosaurs fall under these criteria.

 

"What is a reptile" and "what is a bird" is simply a way for us to better organize species and understand their relationships with one another, where they came from, etc. On a fundemental level, it doesn't matter.

[LilSciWizGal]

Are Birds reptiles?

 

I not sure about that...humm, Pondering Question... But I knoew that they evolved from our reptilian friends, but how can birds be reptiles?

[Skye]

My position is that reptile isn't a correct cladistic grouping, so within a cladistic framework nothing is a reptile. You have amniotes, then within that are mammals, birds, tortoises, snakes & lizards, etc.

 

If you aren't worried about cladistics, then reptiles are all amniotes that aren't birds or mammals. At some point you draw an arbitrary line.

 

Either way, birds aren't reptiles to me.

[Mokele]

Actually, if you classify reptiles as Reptilia = Diapsida, then reptiles do indeed form a meaningful monophyletic clade (paraphyletic only if birds are excluded).

 

The key is chelonians. Formerly, they were the thorn in everyone's side because they represented yet another outbranch of basal anapsids, presumably the sister taxa to the clade of other reptiles + mammals. However, we've always just been *assuming* that chelonians are anapsids (the basal amniotes), and their taxonomy within fossil anapsids has always been confusing and conflicted. But when you treat the anapsid-like skull of chelonians as a secondarily derived feature, you get very strong results putting them within diapsida (though morphological and molecular are in conflict, placing them closer to lepidosaurs and archosaurs respectively).

 

So, if the anapsid skull of chelonians is a secondary reversion to the primitive state, you get two monophyletic clades: Diapsida (lizards, snakes, turtles, crocs, dinos, birds, etc) and Synapsida (mammals). Fossil anapsids would be paraphyleticly grouped, though.

 

Mokele

[Ophiolite]

At some point you draw an arbitrary[/b'] line.

Exactly. All classification systems are artificial, pandering to the human need/skill/tendency to put things in metaphorical boxes.

[Mokele]

True, but, though artificial, they must have at least *some* sort of biological relevance (in how they are defined) for them to be useful as a communication tool.

 

Mokele

[Ophiolite]

I agree completely. However, I suggest that there is a broad band where such a line could be drawn. Anywhere within that band would meet the demands for *some* sort of biological relevance . It seems to me that within this band the debates over where exactly to place the line are based more on good old primate one-apemanship, than on science.