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Dino DNA

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Tidgy's Dad

I think this is a bit odd.

'Birds are one of the most varied groups of animals'? Because they have more chromosomes they evolve faster than mammals?

Really? 

I would argue that mammals have a far greater degree of variability than birds. You look at a penguin and it is still clearly a bird, two feet, wings, even though it swims well and can't fly. A dolphin is so like a fish, many (most?) people think that they are. The physiological differences between a dolphin, a bat and an elephant are huge. Mammals can lay eggs, have pouches, placental babies. Birds is eggs. Mammals are far more intelligent. Etc. Hence mammalian dominance of the majority of ecological niches where birds compete. 

Nice to see a picture of a Tidgy thing though. :)

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WhodamanHD

@Tidgy's Dad

“One of the most” is not a very certain statement!

 

Genetic and morphological variability are very different things. Cope’ Gray tree frog and the Gray tree frog look the same, but genetically they are a different species, one has more chromosomes than the other. A greats Dane and a chihuahua share most of their DNA yet are very different morphologically. This is not to say that they are wrong, though judging by This and This  birds have at least 4,000 more species extant than mammals.

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Tidgy's Dad
31 minutes ago, WhodamanHD said:

@Tidgy's Dad

“One of the most” is not a very certain statement!

 

Genetic and morphological variability are very different things. Cope’ Gray tree frog and the Gray tree frog look the same, but genetically they are a different species, one has more chromosomes than the other. A greats Dane and a chihuahua share most of their DNA yet are very different morphologically. This is not to say that they are wrong, though judging by This and This  birds have at least 4,000 more species extant than mammals.

"One of the most" is a paraphrase of the article that says, "..birds are among the most varied animal groups on Earth." Not only is it not certain, I would say it's highly debatable. 

And the number of chromosomes doesn't account for likelihood of variability, in my opinion. 

Look at the famous fruit fly, Drosophila melanogaster. Just four pairs of chromosomes and morphologically very variable and easy to manipulate. There are over 4,000 species in the family Drosophilidae alone, And if you compare the species number of the classes 'Aves' and 'Insecta', well,  it's pretty one-sided. 

The vertebrates with the most chromosomes are the Northern Lamprey (family Petromyzontinae) with 174 and the American paddlefish with 120. Other groups of fish with far less chromosomes are far more diverse in number of species and morphology. 

So why aren't there thousands of species of lamprey (there are 38 that we know about) or paddlefish ( 6 in the family) ?  

Besides this I know we should factor in length of time the animal group has been extant and the number of extinctions that have occured. 

 

And also that the smaller you are, the more species are possible. Would bacteria or beetles have as many species if they were as large as mammals? Would birds? 

I just find the whole article very unscientific, the pigeon has 80 chromosomes, the red viscacha rat 102, yet the scarlet macaw only 62 - 64 . Were dinosaurs closer to macaws or pigeons? 

Variability within a class is also massive, a 'class' (taking birds as a class) like Insecta has an ant with only one or two chromosomes and a butterfly with 448 to 452. 

The whole thing is wildly speculative at best and is on the BBC news because it's about dinosaurs. 

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WhodamanHD

@Tidgy's Dad I’m gonna be honest, I didn’t really read the article. It’s probably baseless  stuff thrown together for the liking of the masses rather than scientific interest. I agree chromosome number has very little if anything to do with the rate of evolution. 

 

Though I'm not sure I agree with the smaller=more species, seems more like a trend than a rule.

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Tidgy's Dad
8 minutes ago, WhodamanHD said:

@Tidgy's Dad I’m gonna be honest, I didn’t really read the article. It’s probably baseless  stuff thrown together for the liking of the masses rather than scientific interest. I agree chromosome number has very little if anything to do with the rate of evolution. 

 

Though I'm not sure I agree with the smaller=more species, seems more like a trend than a rule.

I'm certainly not saying smaller = more species. 

But I'm saying much bigger = less likelihood of thousands of species. 

 

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