Snakes and the Alaskan land bridge

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AEthelred
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Joined: July 16th, 2019, 9:56 am
Location: North Adams,Massachusetts

Snakes and the Alaskan land bridge

Post by AEthelred »

This is a post on the Alaskan land bridge theory,a belief I hold that North American snakes came from east Asia and crossed the Alaskan land bridge at a time when the climate was hospitable to snakes.

North America has pit vipers and one species of Elapid,the Coral snake which are both found in eastern Asia,there are no pit vipers west of India.

Although old world and new world coral snakes are different,old world Coral snakes are found near where there are a lot of pit vipers in southeast Asia,and there are pit vipers and Coral snakes found in north and south and central America.

It seems clear that pit vipers and Coral snakes crossed into the America's,why else would species indigenous to eastern Asia end up in the America's.

Krait theory:Did new world Corals evolve from Kraits not old world Corals?

New and old world Corals are quite a bit different and Kraits like new world Corals are small,banded,eat snakes,highly toxic venom but small venom yield and live in eastern Asia and could have also made the crossing to the America's.

The big question is why didn't true vipers,which there are some in east Asia and Cobra's also make the crossing? I can't answer that but it clearly seems North and South American snakes came from east Asia.Plus there are no pit vipers west of India (or possibly Pakistan),only true vipers in Africa and Europe.

If American snakes came from elsewhere then why don't we have true vipers or Cobra's.Now Africa did bump into North America millions of years ago which created the Apalachian mountain range from the upheaval of the two continents coliding.However the bump was likely the plates under the two continents that colided,I don't think America and Africa ever connected.Of coarse there was a time when all the continents were connected but this was a very long time ago.

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BillMcGighan
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Location: Unicoi, TN

Re: Snakes and the Alaskan land bridge

Post by BillMcGighan »

I understand why you may think the land bridge was a factor, but, IMHO, it doesn’t seem likely; timing doesn’t seem to match up.


According to ENCYCLOPÆDIA BRITANNICA, “about 80 million years ago, North America separated from Europe, Australia began to rift away from Antarctica, and India broke away from Madagascar. India eventually collided with Eurasia approximately 50 million years ago, forming the Himalayas”.

The major glaciations (Quaternary) that affected human migrations were from about 2.6 million years ago to present.
Our best estimate for the beginning of the land bridge was 20,000 years ago.
Even earlier glaciations which may have had bridges were greatest at 650,000 years ago.

Molecular Phylogenetics put a common ancestor between new world and old world vipers occurring about 28 million years ago.


Ref:
“Diversification in vipers: Phylogenetic relationships, time of divergence and shifts in speciation rates”
By Laura R.V. Alencar a,⇑ , Tiago B. Quental a , Felipe G. Grazziotin b , Michael L. Alfaro c , Marcio Martins a , Mericien Venzon c , Hussam Zaher

Jimi
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Joined: December 3rd, 2010, 12:06 pm

Re: Snakes and the Alaskan land bridge

Post by Jimi »

Thanks for taking the time, Bill. I just couldn't deal with the goofiness. It's a matter of evidence, not of opinion.

cheers

AEthelred
Posts: 41
Joined: July 16th, 2019, 9:56 am
Location: North Adams,Massachusetts

Re: Snakes and the Alaskan land bridge

Post by AEthelred »

Jimi wrote:
April 13th, 2020, 9:37 am
Thanks for taking the time, Bill. I just couldn't deal with the goofiness. It's a matter of evidence, not of opinion.

cheers
I certainly welcome any critical responses and I am not a professional scientist by any means and maybe it's just coincidence that there are similarities between snake species of eastern Asia and North America.

However it is at least compelling that North America has only pit vipers and no true vipers and no cobra's but has elapid species similar to eastern Asia.

I wouldn't call it "goofy" to think there might be a eastern Asia-North America snake correlation,I don't claim to be right and my post if you read it is phrased as sort of a question more than a statement.

However goofy or goofiness is not fair or called.

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BillMcGighan
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Joined: June 7th, 2010, 8:23 am
Location: Unicoi, TN

Re: Snakes and the Alaskan land bridge

Post by BillMcGighan »

AEthelred: “I am not a professional scientist by any means and maybe it's just coincidence that there are similarities between snake species of eastern Asia and North America..”


First, a disclaimer: My thoughts here are those of an interested lay person. My formal zoological training was many, many years ago, so don’t take what I say as anything more than a lay observation, i.e. verify any of my statements through real scientific studies.
Not being a practicing scientist allows me to oversimplify the journey. (Also my kids and grandkids would probably tell you that I’m one of those annoying people who, when you ask for the time, will tell you first how to build a watch!)


Me to you AEth ;) : There is no way I can know the extent of your background in zoology, so please try not to be insulted if I oversimplify too much.


That said, “Similarities between snake species of eastern Asia and North America” are perplexing when viewed through our modern animals, times, places, and distances, but viewed through the evolutionary tree and geology, they are not just coincidence.


Fossil evidence points to a common ancestor of all modern mammals, birds, and reptiles occurred about 300 million years ago (mya).

These creatures were progressing with development through influences of genetics and habitat changes, thus responding to natural selection.
Remember, approximately 80 mya, North America finally separated from Eurasia (Europe and Asia never separated), but the genetics from many of the creatures that came before came across with the move.


Most of the land at this point was a supercontinent and early in the supercontinent there was “Laurasia” where southern, eastern North America was joined to what is now Europe and northern, eastern North America was joined to what is now Asia.


(Don’t give up yet, we’re getting to the good stuff!)

Then the big kill, the K/T catastrophe Cretaceous–Paleogene extinction event about 66 mya, the fifth extinction event our earth has endured.
Before this happened, mammals, birds, and reptiles were established with the birds separating from reptiles about 150 mya..
In short, there were tons of species and branches of the evolutionary tree prior to K/T incident, many of which finished their journey on earth at this time.

After this, as a general statement, you can say all vertebrates today, evolved from the survivors of K/T.
(Except, as we know, of course, for Sasquatch who was from an alien planet!) :lol: :lol: :lol:

Now we’re into researching times, since snake fossils are not as common as some other vertebrates, it is likely that the common ancestor to. New world and old world vipers came across and survived K/T on both continents, North America and Asia. Remember, Phylogenetics can say these particular snakes had a common ancestor approximately 28 mya., but paleontology may confirm this to be a lineage that endured on both continents much earlier.

Bottom line, the genes of these vipers did survive, but for a much longer period of time than the land bridge.

Regards, Bill

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