Mass Extinctions 6 lifeforms 0

[studiot]

http://www.bbc.co.uk/news/science-environment-32397220

 

Comments?

[Mike Smith Cosmos]

 

http://www.bbc.co.uk/news/science-environment-32397220

 

Comments?

Wow! That is fascinating . Just before ( long time really in our terms ) , the greatest Permian mass extinction event .

 

Mike

Edited April 21, 2015 by Mike Smith Cosmos

[pavelcherepan]

http://www.bbc.co.uk/news/science-environment-32397220

 

Comments?

 

studiot, I've read about this one but this is not a discovery per se, but just an attempt to re-classify the known extinction to be on a separate list. Look, for example, at the chart below. The peak of extinction just before the Permian-Triassic "Great Dying" is the one that they want to re-classify. It's already been known and the scale of it is known as well. So this is similar to re-classifying Pluto or Ceres to a dwarf planet. Not really a science, just some administrative work

 

I would also like to correct your scoreboard:

 

Mass extinctions: 6

Lifeforms: Gazillion

 

Edited April 21, 2015 by pavelcherepan

[TheDivineFool]

I wonder what sort of evidence makes 'mass extinction' true? How does the reasoning go?

 

Do they find fossils of a wide variety of life forms at one period of time and the a complete lack of fossil evidence in the time that follows?

 

Surely the evidence must come from fossil records. How come we don't hear of alternative explanations a la dinosaur extinction. There are competing explanations for the Cretaceous mass extinction.

 

Also, if these are truly mass extinctions, what caused them? Isn't that relevant to our own survival as a species?

[studiot]

Here is the film of the book

 

The Day the Earth Nearly Died by M Benton.

 

http://www.dailymotion.com/video/xw5o16_the-day-the-earth-nearly-died_shortfilms

 

PS the book is good too (written by a professor of geology)

[michel123456]

 

studiot, I've read about this one but this is not a discovery per se, but just an attempt to re-classify the known extinction to be on a separate list. Look, for example, at the chart below. The peak of extinction just before the Permian-Triassic "Great Dying" is the one that they want to re-classify. It's already been known and the scale of it is known as well. So this is similar to re-classifying Pluto or Ceres to a dwarf planet. Not really a science, just some administrative work

 

I would also like to correct your scoreboard:

 

Mass extinctions: 6

Lifeforms: Gazillion

 

 

 

Call me wathever you want but I don't like this graph. It is cut at 60% and gives a wrong impression.

It should be like the one below updated roughly by me. The 100% is shown.

 

 

Life is in colour, death in black as usual.

Edited April 22, 2015 by michel123456

[pavelcherepan]

I guess that was simply to save space because on your updated graph the top part has no information at all. Although cutting at 60% is uncool too, gives a wrong impression, you're right.

[michel123456]

I guess that was simply to save space because on your updated graph the top part has no information at all. Although cutting at 60% is uncool too, gives a wrong impression, you're right.

The information is that not everything got extincted. The coloured part is evidently more important than the black fringes, and there is no interruption.

 

It looks like an ancient fabric, a papyrus, or a flag after many years.

and because the time scale on the horizontal is really huge, it should look like this below

 

Now it ressembles a North-South section through India and the Himalayans.

It is much like extinctions happen all the time.

----------------------------

IOW on the diagram, there is never 100% of genera.

Edited April 22, 2015 by michel123456

[studiot]

Forgive me for commenting on your discussion about playing with the presentation of the figures, and I do understand the issues about improper scaling of charts, but what about the provenance of those figures themselves.

 

What does the 'fraction of the general' mean?

 

figures I have seen are between 90% and 99% extinction for the end permian event, and the references I gave go with this figure.

 

Please also note that the original BBC report I linked to presented a balanced view that the BBC are famous for in that they presented both sides of the discussion ie they presented the counter argument as well.

Edited April 22, 2015 by studiot

[imatfaal]

Forgive me for commenting on your discussion about playing with the presentation of the figures, and I do understand the issues about improper scaling of charts, but what about the provenance of those figures themselves.

 

What does the 'fraction of the general' mean?

 

figures I have seen are between 90% and 99% extinction for the end permian event, and the references I gave go with this figure.

 

Please also note that the original BBC report I linked to presented a balanced view that the BBC are famous for in that they presented both sides of the discussion ie they presented the counter argument as well.

 

Not commenting on reliability or conflict of figures. fraction of "genera" not "general"

 

genara is plural of genus . Genus is the taxonomical rank between family and species. Using the wider grouping genus rather than species has both benefits and problems; but it is just as relevant.

90 - 95 percent of species could well only entail 50-60% of genera. Many species were wiped out - but fewer genera (consisting of multiple species) were erased. It is quite easy and plausible to construct a toy scenario in which this is the case - for instance if genera contained 2 - 5 species and in the event on average the 3 least well adapted/most under pressure species from each genera were removed...

[michel123456]

interpretation of graphs are difficult. They give you an image that may not coincide with what really happened.

I don't know for example if it would be reasonable to make a graph of the casualties of a mass extinction. I guess we don't have the data for that, but in everybody's mind a mass extinction means a lot of dead animals, I think. And i don't know if an extinction is something like that: a catastrophic event that kills, or a smooth change (over thousands of years)where a specie has fewer and fewer descendants, or some other mechanism.

[Acme]

studiot, I've read about this one but this is not a discovery per se, but just an attempt to re-classify the known extinction to be on a separate list. Look, for example, at the chart below. The peak of extinction just before the Permian-Triassic "Great Dying" is the one that they want to re-classify. It's already been known and the scale of it is known as well. So this is similar to re-classifying Pluto or Ceres to a dwarf planet. Not really a science, just some administrative work ...

That's true more-or-less, although it may be new to tie the eruption of the Emeishan Traps to this particular extinction event.

 

As to your graph -which I note is not part of Studiot's article- it is well labeled so really not deceptive at all. I would also note that while Studiot's article focuses on animals, plants also go extinct.

[studiot]

Thank you for that clarification, imatfaal, +1