The dinosaur extinction

[kitkat]

Please correct me if I am wrong here it is my understanding that during the dinosaur era that they dominate the entire planet and that the only mammals that existed were ground dwellers.

 

This makes sense to me because given their size I cannot see any other species being able to exist at the same time as them except ones that were night creatures.

 

Here is where it gets confusing to me. Dinosaurs evolved birds. Okay I can see the body of birds could resemble a small dinosaur lineage could produce a bird over time. Now since dinosaurs are considered a reptile and only reptiles can produce reptiles then no mammal species can originate from reptiles during this time frame. It does not mean they could not originate from reptiles but not after the dinosaurs dominated. What is left is the ground dwellers. I have trouble believing that they are entirely responsible for all of the biodiversity of mammals that are alive today.

 

Especially considering that for speciation to occur they have to be isolated from each other. For the numbers to appear they would have to be isolated many times simultaneously all over the globe. Another problem is DNA shuffling and all of the mechanisms that are believed in the process has a limit on how far it can go in every species that we define.

 

There just doesn't appear that this could happen in the time frame its stated and the land mass is not sufficient in space for them to be isolated from each other.

[Moontanman]

Please correct me if I am wrong here it is my understanding that during the dinosaur era that they dominate the entire planet and that the only mammals that existed were ground dwellers.

 

Tree dwellers might be more accurate for many but most were small insectivores. Like shrews, possums, and several other linages but very small.

 

This makes sense to me because given their size I cannot see any other species being able to exist at the same time as them except ones that were night creatures.

 

Many if not most mammals of the time were thought to be nocturnal.

 

Here is where it gets confusing to me. Dinosaurs evolved birds. Okay I can see the body of birds could resemble a small dinosaur lineage could produce a bird over time. Now since dinosaurs are considered a reptile and only reptiles can produce reptiles then no mammal species can originate from reptiles during this time frame. It does not mean they could not originate from reptiles but not after the dinosaurs dominated. What is left is the ground dwellers. I have trouble believing that they are entirely responsible for all of the biodiversity of mammals that are alive today.

 

Again you have your information confused, mammals appeared before dinosaurs appeared but the dinosaurs out competed and suppressed the mammals for 150 million years. They both developed from different linages of reptiles, this is an example of the type of reptiles mammals evolved from.

 

 

 

 

Especially considering that for speciation to occur they have to be isolated from each other. For the numbers to appear they would have to be isolated many times simultaneously all over the globe. Another problem is DNA shuffling and all of the mechanisms that are believed in the process has a limit on how far it can go in every species that we define.

 

I think I've answered this one but if not i'll try again...

 

There just doesn't appear that this could happen in the time frame its stated and the land mass is not sufficient in space for them to be isolated from each other.

 

That's because you have your time frame confused....

[Sisyphus]

Well, first of all, we're not dealing with a common ancestor 65 MYA. There were already many species of mammals at that time, as true mammals have been around for about 200 million years. (Plus, remember, there's only about 5000 mammals species today.) You're only dealing with the speciation of, say, primates in that time frame, rather than all mammals.

 

Second, they don't have to be simultaneously speciate everywhere at once. Why would they? It's a tree of life, with branches splitting into more branches at later dates. Not a lawn of life, where everything starts at once. Speciation still happens today. If a bat species diverges into two populations, obviously that doesn't require that it be isolated from all other mammals or all other life, just one another.

 

Third, what, specifically, is hard to believe? 65 million years seems like an extremely long time to me.