Not only did birds EVOLVE from Dinosaurs, birds ARE Dinosaurs! Christians: sound off if this is NOT a problem for you! [Spirituality & Religion]

@Viper

Well to give a broad answer, crocodilians and monitor lizards like the komodo are not dinosaurs because unlike birds they don't share a number of physical characteristics that dinosaurs have.

Dinosaurs and crocs are all members of the reptile group but crocs do not share the specific characteristics that identify a dinosaur as a dinosaur.
In a similar way, fish have backbones and mammals have backbones which makes them both members of Chordata but many obvious characteristics separate them.

Same thing with dinosaurs and birds vs crocodilians.

@Pikachu Yes, I've read that somewhere else as well, but they didn't list what these specific characteristics are... so I was left wondering what traits are they talking about.

In that, someone mentioned legs lifting the body off the ground, which doesn't makes sense to me, as Crocs can lift their body off the ground, they just prefer not to as it takes more energy, except maybe when they want to move on land.


But I'm just trying to figure out how birds are closer related to the non-avian dinosaurs (which were reptiles) than any modern reptile.

There could be an absolute great answer, I'm not doubting that... it's just I don't know it and haven't heard a good understandable explanation.

@Viper

There are indeed a number of technical characteristics that place birds in the group of dinosauria.
If you're interested just listen to the opening statement of this debate starting at 4:00. He goes over a number of those morphological features.
[youtube=https://www.youtube.com/watch?v=aS8h-n2gSUc]

[quote]I'm just trying to figure out how birds are closer related to the non-avian dinosaurs (which were reptiles) than any modern reptile.[/quote]

The answer is that there is a direct evolutionary line through descent between maniraptoran dinosaurs and modern birds while all modern reptiles branched off much earlier on.

@Pikachu He did a great job explaining why Birds and dinosaurs and not lizards.

But he was mistaken that only birds have hard shells. Crocodiles have hard shells just like birds.

https://crocodilian.com/cnhc/cbd-mor1.htm

[quote]Crocodile eggs, unlike other reptile eggs, consist of a soft, inner membrane and a hard, calcified outer membrane - very similar to a bird's egg. [/quote]

@Viper

Yeah i think there are a few reptile species that actually have calcified egg shells so that's not super diagnostic.

@Pikachu I think I finally figured it out! My assumption that Crocs seem old as sh!t, why aren't they dinosaurs is NOT wrong!

What was mistaken was my assumption that Dinosaurs are older than sh!t so they must of lead to the modern looking dinosaur.

The trick is that certain animals ancestors such as Jellyfish, Fish, Shark, Turtle and Crocodile... broke away from the Dinosaurs ancestors BEFORE there were dinosaurs. (In reality, it was probably the Dinosaur that broke away as they're the most land based animals of all these).


Without going all the way up...

There were Archelosauria (think Turtles, Crocodilians and Dinosaurs)

Then the Turtles broke into their own group. This left just archosaurs (Crocodilians and Dinosaurs)

Then the Crocodilians (also known as Pseudosuchia) broke into their own group. Leaving just the animals that would later become the Dinosaur.

Then the dinosaurs would become avian and non-avian dinosaurs.


[b][u]In other words, Crocs aren't a dinosaur because their common ancestor was from BEFORE dinosaurs existed.[/u][/b] Where Birds common ancestor goes right through the dinosaurs.

@Viper

[quote]In other words, Crocs aren't a dinosaur because their common ancestor was from BEFORE dinosaurs existed. Where Birds common ancestor goes right through the dinosaurs.[/quote]

Bingo👍
Crocodilian ancestors diverged before dinosaurs evolved while birds arose directly from the dinosaur lineage.

@Pikachu Yeah, it's just in my mind Dinosaurs = extremely old as sh!t...

So thinking of Crocodiles as older, is where I wasn't connecting as they're clearly still around. Guess their design is so good they haven't needed to change.

@Viper Yup that's evolution for you. If it ain't broke then don't fix it.
Sharks are even older. They predate dinosaurs by many millions of years.

@Pikachu Now this is just 100% theory/wild @$$ guess and wondering...

But if birds are the only one to make it past an event, and it's my understanding that birds could basically fish, or grab fish from the ocean.

I wondering if the event that took out the non-bird dinosaurs blocked the sun light and cooled it enough, where so all the plants died and followed by the plant eatting dinosaurs and then the meat eatting dinosaurs.


Basically, you had to be able to get enough food from the ocean or you die...

That or there was a shift in the poles which allowed in more solar radiation (which is what recent science believes strongly effected the neanderthals, making them hide in caves more often to stay out of the radiation which was burning or killing them) which then hurt their hunting.

In the case of the dinosaurs, the feathers might of helped with radiation... if birds come from muliple different dinosaurs.

@Viper Actually aquatic life suffered far more so i'm not sure how available aquatic food sources would be.
But my understanding is that basically animals over a certain size tend not to survive massive climate related disasters because of things like available resources and shelter. This is of course a generalization and certain adaptations help as well (eg> the crocodilian ability to nearly halt their metabolic processes in times of sever resource deficiency).
I don't know about radiation protection but birds like mammals are able to regulate their body temperature so that would surely give them an advantage as well.