Some ancient groups of animals go completely extinct.

The pterosaurs were the first flying vertebrates. For 140 million years they flew. The Pterodactyl is the most well-known of these but there were many kinds, with a great variety of shapes and dimensions. Quetzalcoatlus for instance was, to the best of our knowledge, the largest flying animal ever to exist, with a wingspan of 10 metres. However, there are no pterosaurs today, and no descendants of them. The last of them went extinct 65 million years ago, in the K-T extinction event.

The dinosaurs arose around the same time as the pterosaurs, some 230 million years ago, and of course were also very diverse. Some 160 million years ago, a subset of the dinosaurs developed feathers and it is believed all of their descendants also had feathers. This was probably a crucial adaption. The K-T extinction did not quash the dinosaur family tree: their descendants the birds are still with us today.

240 million years ago, before the dinosaurs or pterosaurs arose, the sphenodontians diverged from the lizards. They are distinguished by their beaklike upper jaw which is fused to the rest of the skull, ie the quadrate bone is immobile. The sphenodontians were also a very diverse group, ranging from the small planocephalosaurus to the large Priosphenodon avelasi, and include the water-dwelling pleurosaurus. There were dozens of genera, and at their peak the sphenodontians covered the globe. Just by antiquity, the sphenodontians are a more major division of vertebrates than the birds, the mammals, the snakes or the crocodilians.

By the end of the Cretaceous, the diversity had declined, but somehow the spenodontians did survive the K-T extinction event that wiped out the pterosaurs and non-avian dinosaurs. As a group, though, they continued to decline: perhaps for some reason they were outcompeted by lizards, snakes, mammals, crocodilians and birds.

The sphenodontians have survived to the modern era, but barely. There is one remaining species: the tuatara is all that remains of this ancient clade. The tuatara is only found on a few dozen small islands offshore from New Zealand. It is known that it was wiped out from North Island some time between the arrival of the Maori and the arrival of Europeans: it has been suggestion that the cause was the introduction of the rat. It was previously thought there were two separate species but these are now considered geographical variants of the same species. There are tens of thousands of tuataras remaining and its conservation status, according to the IUCN, is “vulnerable”.

There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years.

Some ancient groups of animals go completely extinct.

—-

I thought it was like 99%?

tuatara

thanks – never heard of them before.

tauto said:

Some ancient groups of animals go completely extinct.

—-

I thought it was like 99%?

—-

Begs the question; can you go partially extinct?

tauto said:

Begs the question; can you go partially extinct?

No, it doesn’t. Don’t want to sound pedantic, but that’s not what ‘begs the questions’ means.

tauto said:

tauto said:

Some ancient groups of animals go completely extinct.

—-

I thought it was like 99%?

—-

Begs the question; can you go partially extinct?

The distinction I was making is clarified by the first three paragraphs of the OP, but the reiterate: The pterosaurs, as a group, are extinct. The non-avian dinosaurs are also extinct, but their line was not completely discontinued inasmuch as their descendants the birds still survive. There are plenty of major groups in each category, I have not crunched the numbers so I couldn’t tell you which is the common case.

Rule 303 said:

tauto said:

Begs the question; can you go partially extinct?

No, it doesn’t. Don’t want to sound pedantic, but that’s not what ‘begs the questions’ means.

—

quite right, it was a tautology

> The pterosaurs were the first flying vertebrates.

Possibly, there was also a flying lizard that was around before the first birds appeared. No descendents of it are known. Let me check. “Longisquama insignis” was a lizard whose wings were constructed from extended ribs. It lived 220 million years ago. The first pterosaurs about about 228 million years ago. It’s a close call.

> 240 million years ago, before the dinosaurs or pterosaurs arose, the sphenodontians diverged from the lizards. They are distinguished by their beaklike upper jaw which is fused to the rest of the skull, ie the quadrate bone is immobile. The sphenodontians were also a very diverse group, ranging from the small planocephalosaurus to the large Priosphenodon avelasi, and include the water-dwelling pleurosaurus. There were dozens of genera, and at their peak the sphenodontians covered the globe. Just by antiquity, the sphenodontians are a more major division of vertebrates than the birds, the mammals, the snakes or the crocodilians.

I didn’t know that. The Tuatara is the only sphenodon that I’m familiar with.

> The tuatara was wiped out from North Island some time between the arrival of the Maori and the arrival of Europeans. There are tens of thousands of tuataras remaining and its conservation status, according to the IUCN, is “vulnerable”.

I didn’t know that, thanks again.

The tuatara is one of a hundred or so “living fossils”. Among the vertebrates, the justly most famous “living fossil” is the coelacanth. The tuatara is separated from its closest living relatives by 240 million years. The coelacanth is separated from its closest living relatives by a massive 400 million years.

tauto said:

Begs the question; can you go partially extinct?

Did neanderthal man go partially extinct? I’m 3% neanderthal.

The tuatara skull

I don’t have a problem with completely and partially extinct (since any group that contains an extinct sub-group is partially extinct) but

dv said:

There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years

I thought all living things shared the same common ancestor.

The Rev Dodgson said:

I don’t have a problem with completely and partially extinct (since any group that contains an extinct sub-group is partially extinct) but

dv said:

There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years

I thought all living things shared the same common ancestor.

They do.

Please read my statement more carefully.

dv said:

The Rev Dodgson said:

I don’t have a problem with completely and partially extinct (since any group that contains an extinct sub-group is partially extinct) but

dv said:

There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years

I thought all living things shared the same common ancestor.

They do.

Please read my statement more carefully.

Can you give us a hint?

The Rev Dodgson said:

I don’t have a problem with completely and partially extinct (since any group that contains an extinct sub-group is partially extinct) but

dv said:

There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years

I thought all living things shared the same common ancestor.

OK, I think I’ve got it, the “lived more recently than 240 million years” applies to the common ancestor, not the tuatara.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

I don’t have a problem with completely and partially extinct (since any group that contains an extinct sub-group is partially extinct) but

I thought all living things shared the same common ancestor.

They do.

Please read my statement more carefully.

Can you give us a hint?

Maybe it’s a bit early. I’m not getting what you’re not getting. I read my statement and it appears to me to be an unambiguous statement of undeniable truth.

“There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years”

no living creature today.. makes sense to me

dv said:

The Rev Dodgson said:

dv said:

They do.

Please read my statement more carefully.

Can you give us a hint?

Maybe it’s a bit early. I’m not getting what you’re not getting. I read my statement and it appears to me to be an unambiguous statement of undeniable truth.

See my last post.

I took it to mean:
“The tuatara that lived more recently than 240 million years do not have common ancestors with any living animal “

whereas I now think you meant.

The tuatara does not have common ancestors with any living animal within the last 240 million years.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

Can you give us a hint?

Maybe it’s a bit early. I’m not getting what you’re not getting. I read my statement and it appears to me to be an unambiguous statement of undeniable truth.

See my last post.

I took it to mean:
“The tuatara that lived more recently than 240 million years do not have common ancestors with any living animal “

whereas I now think you meant.

The tuatara does not have common ancestors with any living animal within the last 240 million years.

I think that last sentence is confusing.

I haven’t had my coffee yet.

In pieces:

The tuatara and any other living animal have a set of common ancestors.

This set will depend on “the other living animal”.

However, regardless of what “other living animal” you choose, this set of common ancestors with the tuatara will contain no members that existed more recently than 240 million years ago.

dv said:

However, regardless of what “other living animal” you choose, this set of common ancestors with the tuatara will contain no members that existed more recently than 240 million years ago.

Just goes to show that ambiguity is in the eye of the beholder, but I think your last statement above says the same thing as I meant in my last statement, so I now think I know what you think on this subject.

Whether it’s an undeniable truth is another matter. I mean surely there might have been common ancestors that we don’t know about.

But maybe that’s getting a bit pedantic.

semantics

The Rev Dodgson said:

dv said:

However, regardless of what “other living animal” you choose, this set of common ancestors with the tuatara will contain no members that existed more recently than 240 million years ago.

Just goes to show that ambiguity is in the eye of the beholder, but I think your last statement above says the same thing as I meant in my last statement, so I now think I know what you think on this subject.

Whether it’s an undeniable truth is another matter. I mean surely there might have been common ancestors that we don’t know about.

But maybe that’s getting a bit pedantic.

No, fair enough. More evidence may come to light.

what if ‘u wrote,

/* There is no living animal that shares with the tuatara a common ancestor that lived more recently than 240 million years ago. */

instead of

/* There is no living animal that shares a common ancestor with the tuatara that lived more recently than 240 million years. */

;

league is a real doozy… at least over here in Qld it is…

I thought soccer was bad at times, but I can tell you that parents at junior rugby league games take the cake in terms of poor behavior. Yelling at the kids, yelling at the ref, yelling at the parents/supporters of the other team… The worst group I saw were all sitting on the sideline sculling beers and yelling abuse.

We only played one season that was the boys one and only foray into the world of rugby league.

wrong fred

diddly-squat said:

league is a real doozy… at least over here in Qld it is…

I thought soccer was bad at times, but I can tell you that parents at junior rugby league games take the cake in terms of poor behavior. Yelling at the kids, yelling at the ref, yelling at the parents/supporters of the other team… The worst group I saw were all sitting on the sideline sculling beers and yelling abuse.

We only played one season that was the boys one and only foray into the world of rugby league.

What sort of power do the refs have for banning such parents?

diddly-squat said:

league is a real doozy… at least over here in Qld it is…

I thought soccer was bad at times, but I can tell you that parents at junior rugby league games take the cake in terms of poor behavior. Yelling at the kids, yelling at the ref, yelling at the parents/supporters of the other team… The worst group I saw were all sitting on the sideline sculling beers and yelling abuse.

We only played one season that was the boys one and only foray into the world of rugby league.

Try rugby union. The gentleman’s game.