The Naked Scientists

The Naked Scientists Forum

Author Topic: What causes mass extinctions?  (Read 4343 times)

Offline PaddyB

  • First timers
  • *
  • Posts: 1
    • View Profile
What causes mass extinctions?
« on: 17/06/2015 10:30:40 »
There is a lot of speculation and fact surrounding the various mass extinction events and those that relate to major impact events all refer to landing on the continents. Given that there is more water covering the planet than solid earth there must have been many more impacts in the ocean than on land. I realise that the vast majority of these water impacts energy would have been absorbed, but I was wondering if there would have been any major consequences of really large objects striking the oceans or was this energy also largely dissipated?
« Last Edit: 17/06/2015 15:08:12 by chris »


 

Online chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1879
  • Thanked: 145 times
    • View Profile
Re: Mass extinctions and causes
« Reply #1 on: 17/06/2015 13:56:44 »
My understanding is that the impact itself was not a direct cause of any of the extinction events, but rather all of the particulate matter kicked up into the atmosphere, causing an abrupt climate change (like a nuclear winter, enough dust in the atmosphere blocks the sun enough to significantly chill the globe). A huge impact in the ocean won't eject nearly as much dust as an impact on dry land.
 

Online evan_au

  • Neilep Level Member
  • ******
  • Posts: 4130
  • Thanked: 247 times
    • View Profile
Re: What causes mass extinctions?
« Reply #2 on: 18/06/2015 11:15:45 »
Quote from: PaddyB
any major consequences of really large objects striking the oceans?
Tsunamis can carry the energy of an impact thousands of miles from the point of impact within a few hours of the impact. This is more rapid than the slower dispersal of dust through the atmosphere, but would not reach very far into the centre of continents.

Quote from: PaddyB
major impact events all refer to landing on the continents
I saw a theory that a large impact would leave a hole in the atmosphere - vacuum reaching the ground behind the descending meteorite. This would carry dust and rock from the impact out of the atmosphere into a suborbital trajectory, falling back into the atmosphere all over the planet for the next few hours.

Calculations suggested that the entire surface of the planet could be subjected to temperatures similar to a pizza oven for hours after the impact, leading to immediate global sterilisation of the surface.

Only plants and animals protected by a reasonably thick layer of soil or water would be able to survive these conditions, to emerge into a blighted and unrecognisable landscape.
 
The following users thanked this post: puppypower

Offline nicephotog

  • Sr. Member
  • ****
  • Posts: 387
  • Thanked: 7 times
  • H h H h H h H h H h
    • View Profile
    • Freeware Downloads
Re: What causes mass extinctions?
« Reply #3 on: 17/10/2015 11:09:35 »
 
Quote
but rather all of the particulate matter kicked up into the atmosphere, causing an abrupt climate change (like a nuclear winter, enough dust in the atmosphere blocks the sun enough to significantly chill the globe)
If "dust" breathing would be a concern...

Outside of your before mentioned, probably immune system collapse or immune system inability to cope by either starvation by nutritional substance lacked or outright biological failure against a disease or new disease e.g. viruses being the simplest and often most effective resistant against organisms immune defenses.

Note: On the thought tsunami and ocean destroying toward inland, i have often thought Hominids evolved beside the ocean on shorelines, this is because of washing - "hygiene" and physical security from large land dwelling creatures that could get vulnerable in sand. Some of this idea relies on encephalisation and IQ development in the human, with the oddity of Hominids perhaps developing the ability to psycho analyse and recognise other creatures learning behavior, such as it understanding whether it is becoming vulnerable during its fossicking e,g, on sand with a weight on its feet of tonnes.

I could not find reason to believe prehistoric - to fore-runner humans would ever survive well (inclusive using engineering ability) "inland" !!!

If you look at a demographic of the instances of Ergasta and Erectus of 2 million years it shows clearly that hominids are found inland, but the subtlety is any specimens of hominids of any era are rare, so much so they rank far less against extinct species fossils that have less ability to reproduce or traverse(a bit guessed) in quantity and demographics of finds.

Not so much mass extinction, but many easy ways such as minor tsunami , accident such as ocean current "rip" on beaches and sharks or wales could commit a severe toll on many complete large populations "en masse".
Sharks could be lucky to eat complete settlements if some creatures were stomping the rocks and beaches.

Sand itself to walk on could account some of the evolution of the upright walk of humans as google earth shows many sections of beach followed by rock at either end to fossick food from.

What would survive large waves reaching above beaches is anything learning to live in upper rock overhangs and it corresponds humans "keeping climbing limbs and abilities" the tree dwelling ancestor had.
Of living in rocks above, what would teach hominids to swim would be bees and wasps, as that is a concern those species have with living somewhere.

So i suppose you would find fossils out a 100 meters from where prehistoric shoreline is or in 100 meters from that same boundary line.

Either way, it's not unlikely for humans but in the mass extinction context, while not extinct it could be where human numbers both thrived and died in immense numbers not long after leaving the trees and when they began modifying to make implements.
If there was enough food then Homo Cautus cannot be assumed to learn its lesson from catastrophe! (Japan is a living fossil record to that point with so much Sushi around the edges).

The biggest problem i see in the idea is the food  itself, and this where beaches and ocean edge rock overhangs lend a huge hand to Hominids as a carnivore! (i.e. Lemming hunting)
Modifying the environment and pieces for tools is one thing, the food is another, and so is hunting.
At the time there is not much brain space, nothing has developed a large brain cavity, so it's time to get some water. However, ocean water is too salty in most mammal metabolisms so it can be limited to find except at river-stream outlets to the ocean of which it will be brackish.
Anything drinking salt water for the first or second time will need to learn it only makes thirst worse, and may be the substance of many kills in prehistoric times whether chased for a short distance or sitting on the sand to die.
This is a "possible meeting point in prehistory for wolves and Hominids" because of the timeline of encephalisation quotient.
So now we have an animal on the sand dying and we have a post-ceder of tree hominids whom cannot walk upright well standing on the beach with a bludgeon tree branch a little taller than him we'll call Harry.
Also we have Homo Cautus on the beach with a much longer tree branch three times his height in length we'll call John.
Harry requires to get to the creature to bludgeon it before Homo Cautus scares it away causing everyone to get nothing but cannot walk well or move quickly over sand because of foot size and shape(where' a podiatrist when you need one). One stick only gives help on one side and as he watches John he learns to recognise John has signs of thinking and getting an idea, so he will need to work fast.
John carries the long branch around because it gives him some ability to handle creatures at a distance enabling safety and putting leaves bound to the top on it he can use it as shade at midday but can also sleep in the natural position for the era at the top of it out of harms way of things below.
Harry decides to commit some engineering to counter the undeveloped feet and breaks the branch he has in two, which is a good idea as it allows balance either side and a spare bludgeon.
Moving quickly for lack of better way of saying it, they move to the mammal creature on the beach.
John waves the leafy end at the creature to test its status of health and fitness , it erupts and John jams the branch into the sand and climbs to the top.

A (8 - 6 million years). Harry finally reaches it but it manages to outstrip his poor gate. Finally Harry reaches it after it falls to the ground from the difficulty of moving quickly over sand and its' immense thirst taking its toll, then, remembering many lessons of fighting such creatures, drops the bludgeons, grabs it and breaks its neck.

B (2 - 4 million years). Harry finally reaches it but it manages to outstrip his poor gate and a pair of wolves try to tackle it but are dragged with it, However, are slowing it. Finally Harry reaches it, with the wolves slowing it and and remembering many lessons of fighting such creatures, drops the bludgeons, grabs it and breaks its neck.

At 8 - 6 million years for Hominids, it suggests that something like "the Japan scenario above" exists for such an intelligent creature of versatility at food-stuffs for metabolic nutrition, but lack of real evidence of their entire existence. However, catastrophe combined in the same exact environment with immense success is a plausible reason for failure of Early Hominids to be found in real numbers inland of which rock overhangs and caves by the ocean is a much more sensible place than the same rock overhangs and caves ever used inland. Inland i believe would more likely be temporary settlement and where any real structural engineering of the environment would be learned and that "generally means wood for most Hominids", rock is more of an exceptional activity in terms of structural engineering and not much good in earthquakes.

* A note about wolves whether early era or later, running prey into water as entrapment is considered part of Canidae "herding instinct".
* note bees are an interesting problem, imagine leaving your tree only because you always get the one with bees and follow the other apes along to the sea shore to live in overhanging rocks, then a year or less later you find bees on the roof of your overhang shelter!

However, the ocean "water environment" itself as bounty enough would be a question, and given its 4 - 8 million years previous development of the brain in edible sea creatures, it becomes questionable what goes on inside such a mind of a fish.
We do know they probably"school", so from that we also in witnessing at present time divers, we know they often do not have much thought in their presence but can question one detail of swimming in a lateral position as a human alike many sharks and other creatures that have swarms of school around them.

The following videos propose the idea is simple enough as no fancy footwork is needed, just an ability to recognise to construct a wooden spear, then we can see the quantity of food for harvest to sustain a population.


Here is a tool that helps considerably in understanding the ease with which fishing can occur at prehistoric levels.
From it's use, it causes observing fish and learning environment behavior of the creature. I had a long argument in forum about fish and their sensitivity of seeing something above the ocean surface move.
Those in the boats in then outer reach away from shore-line or bowfishing bow in a boat feel the creatures care little to see something move above the surface! , most people with a rod or bow-fishing bow on the shore-line will tell you that to move near a fish that is close to the shore-line will cause it to take flight!
It is a point to establish "what and why", would put whole communities in peril of obliteration near the sea shore alike Japan.

What causes mass extinctions?
Perhaps an earthquake of 9 on the Richter scale that upset overhanging bees causing the heavily populated group living in the rock overhangs beside the ocean to jump into the ocean among hungry sharks during a giant super Typhoon, and then with a following tsunami because of the close epicenter of the quake that shifts a rip current across the face of the ocean shore settlement.

These "collective" modern records confirm the ability of them.
Typhoon Haiyan, known in the Philippines as Typhoon Yolanda killed 6,300 in the Philippines alone.
On March 11, 2011, a magnitude-9 earthquake shook northeastern Japan, and had following tsunami. report confirmed 15,893 deaths.
2004 Banda Aceh earthquake and tsunami in Sumatra, a magnitude-9.1, which killed more than 230,000 people
1976 Tangshan earthquake 650,000779,000 deaths.
Sums up one possibility.
« Last Edit: 18/10/2015 06:03:24 by nicephotog »
 

Offline AdamRobinson

  • First timers
  • *
  • Posts: 6
    • View Profile
Re: What causes mass extinctions?
« Reply #4 on: 19/10/2015 09:47:37 »
What event happened where there was an impact or volcano and everything was covered in nickel? Or maybe it was diamond flakes? Has anyone read about this?
 

Online evan_au

  • Neilep Level Member
  • ******
  • Posts: 4130
  • Thanked: 247 times
    • View Profile
Re: What causes mass extinctions?
« Reply #5 on: 19/10/2015 18:29:33 »
Quote from: AdamRobinson
What event happened where there was an impact
Perhaps you are thinking of the Chicxulub crater in Mexico, which is thought to have caused the demise of the dinosaurs?
Quote
or volcano
Perhaps the Deccan Traps, a massive basalt flow in India, which is thought to have contributed to the demise of the dinosaurs.
Quote
everything was covered in nickel?
There is a group of dense nickel-iron meteorites, that tend to make it to ground level more often than some other groups of meteorites.
Quote
Or maybe it was diamond flakes?
The high pressures generated by crashing meteorites (on Earth or in space) can turn carbon into microdiamonds or nanodiamonds.
 

Online chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1879
  • Thanked: 145 times
    • View Profile
Re: What causes mass extinctions?
« Reply #6 on: 20/10/2015 18:10:11 »
What event happened where there was an impact or volcano and everything was covered in nickel? Or maybe it was diamond flakes? Has anyone read about this?

I believe you may be talking about the thin layer of iridium that was spread over the Earth from the meteorite that killed the dinosaurs. https://en.wikipedia.org/wiki/Alvarez_hypothesis#Evidence
 
The following users thanked this post: chris, evan_au

Offline nicephotog

  • Sr. Member
  • ****
  • Posts: 387
  • Thanked: 7 times
  • H h H h H h H h H h
    • View Profile
    • Freeware Downloads
Re: What causes mass extinctions?
« Reply #7 on: 26/10/2015 04:20:02 »

Of below, most 8 million - 2 million year previous hominid finds do not appear to show serious signs of people gathered e.g. alike they think of villages, settlements, stone henge, small groups.
[/size]Many appear to be a lone human with undertones of truly losing the fight for survival with all that can be picked of where they probably were for the ancient geology.
[/size]
[/size]Oceans, have so much to offer the discerning investor and developer and perhaps simply the Australopithecine family![/size]

Note: On the thought tsunami and ocean destroying toward inland,
[/size]i have often thought Hominids evolved beside the ocean on shorelines[/size], this is because of washing - "hygiene" and physical security from large land dwelling creatures that could get vulnerable in sand. Some of this idea relies on encephalisation and IQ development in the human, with the oddity of Hominids perhaps developing the ability to psycho analyse and recognise other creatures learning behavior, such as it understanding whether it is becoming vulnerable during its fossicking e,g, on sand with a weight on its feet of tonnes.[/size]I could not find reason to believe prehistoric - to fore-runner humans would ever survive well (inclusive using engineering ability) "inland" !!!If you look at a demographic of the instances of Ergasta and Erectus of 2 million years it shows clearly that hominids are found inland, but the subtlety is any specimens of hominids of any era are rare, so much so they rank far less against extinct species fossils that have less ability to reproduce or traverse(a bit guessed) in quantity and demographics of finds.
 
The following users thanked this post: AdamRobinson

Offline puppypower

  • Hero Member
  • *****
  • Posts: 559
  • Thanked: 43 times
    • View Profile
Re: What causes mass extinctions?
« Reply #8 on: 26/10/2015 11:11:11 »
Quote from: PaddyB
any major consequences of really large objects striking the oceans?
Tsunamis can carry the energy of an impact thousands of miles from the point of impact within a few hours of the impact. This is more rapid than the slower dispersal of dust through the atmosphere, but would not reach very far into the centre of continents.

Quote from: PaddyB
major impact events all refer to landing on the continents
I saw a theory that a large impact would leave a hole in the atmosphere - vacuum reaching the ground behind the descending meteorite. This would carry dust and rock from the impact out of the atmosphere into a suborbital trajectory, falling back into the atmosphere all over the planet for the next few hours.

Calculations suggested that the entire surface of the planet could be subjected to temperatures similar to a pizza oven for hours after the impact, leading to immediate global sterilisation of the surface.

Only plants and animals protected by a reasonably thick layer of soil or water would be able to survive these conditions, to emerge into a blighted and unrecognisable landscape.

This is very reasonable. The question this brings to my mind is; do we see a continuity in deeper ocean life, that shows less sign of mass extinction, due to the buffering affect of water to short terms changes in the atmosphere and surface, caused by asteroids?

Could the extinction of the dinosaurs and the rise of mammals have been the result of something simple like egg stealing? An asteroid event could have caused a cooling trend, that changes the food supply for whatever survives the blast. Eggs will make a nice interim meal. The dinosaurs would have slowed down due to the cold and can't defend against the quicker warm blooded mammals. The adults may survive, but the next generation is decimated. Mammals bear their young live and would have an advantage when conditions have restored.

 
« Last Edit: 26/10/2015 11:13:02 by puppypower »
 

Offline nicephotog

  • Sr. Member
  • ****
  • Posts: 387
  • Thanked: 7 times
  • H h H h H h H h H h
    • View Profile
    • Freeware Downloads
Re: What causes mass extinctions?
« Reply #9 on: 29/10/2015 06:01:34 »
Quote
...Given that there is more water covering the planet than solid earth there must have been many more impacts in the ocean than on land...

Once again, here is where it is better to be a bad child or maniac than a scientist to think it out and go fishing with hand grenades, as the following shows.



The principals of fluids and compression is much the same with energy transfer as with solids.
Many of the oceans creatures are not particularly edible and quite poisonous. An abundance of foodstuffs to try from such an impact that were rotten after washing up can be one problem, such too,(also) bacterial and virus development that would not normally make contact with land dwellers.

...Would give it now in thinking about it, if a meteorite (the size of created some craters that can be seen from space) hit the ocean in an extremely densely populated environment the result could be catastrophic for land dwellers , with , outside of a tsunami managing to strike from that size hit, and not actually reaching shore(tsunami wave).
....An upset ecosystem in need of more than panadol or dexsal!

Quote
The dinosaurs would have slowed down due to the cold and can't defend against the quicker warm blooded mammals.
Given that enough time had elapsed to have mammals evolve.

« Last Edit: 29/10/2015 06:11:00 by nicephotog »
 

Offline puppypower

  • Hero Member
  • *****
  • Posts: 559
  • Thanked: 43 times
    • View Profile
Re: What causes mass extinctions?
« Reply #10 on: 29/10/2015 13:14:40 »
Say we had a hot asteroid event, followed by a cooling trend due to the dust. Logically this would impact the surviving plant eater animals first due to loss of plant food. As these animals slow down from hunger, the carnivores would have a field day due to so much easy food. As the caucuses of animals decay, now the scavengers would have a field day. Do we see a mass extinction with least disruption in the scavengers?

In the oceans and lakes a similar thing would occur. The plant eaters will weaken and die. This means a field day for the carnivores. As things rot, then the cat fish, crabs and other scavengers would have a field day. The ocean scavengers would have the best chance for maintaining the most continuity. Is this observed based on using the selective advantage arguments of evolution.

Another question that comes to my mind is why did animals like crocodiles, turtles, sharks, who were there with the dinosaurs, not go extinct? These prodigy of the dinosaur are not scavengers but tend to be carnivores.
 

Offline nicephotog

  • Sr. Member
  • ****
  • Posts: 387
  • Thanked: 7 times
  • H h H h H h H h H h
    • View Profile
    • Freeware Downloads
Re: What causes mass extinctions?
« Reply #11 on: 01/11/2015 06:30:27 »
Of "dust" in such an event, maybe choking larger but primitive developed organ animals , bees have primitive lungs so keepers use smokers to weaken them by starving them of oxygen.
 

Online chiralSPO

  • Global Moderator
  • Neilep Level Member
  • *****
  • Posts: 1879
  • Thanked: 145 times
    • View Profile
Re: What causes mass extinctions?
« Reply #12 on: 02/11/2015 18:52:03 »
Say we had a hot asteroid event, followed by a cooling trend due to the dust. Logically this would impact the surviving plant eater animals first due to loss of plant food. As these animals slow down from hunger, the carnivores would have a field day due to so much easy food. As the caucuses of animals decay, now the scavengers would have a field day. Do we see a mass extinction with least disruption in the scavengers?

In the oceans and lakes a similar thing would occur. The plant eaters will weaken and die. This means a field day for the carnivores. As things rot, then the cat fish, crabs and other scavengers would have a field day. The ocean scavengers would have the best chance for maintaining the most continuity. Is this observed based on using the selective advantage arguments of evolution.

Another question that comes to my mind is why did animals like crocodiles, turtles, sharks, who were there with the dinosaurs, not go extinct? These prodigy of the dinosaur are not scavengers but tend to be carnivores.

I think the logic of this argument is too short-sighted. Even if the plants and herbivores are assumed to be the "first" to suffer, I think that it would actually lead to carnivore extinctions quite quickly. Even if we imagine that there is a "field day" for carnivores for a few months, very quickly the carnivores will be short of food if their prey is suffering.

I am fairly certain that it is often the animals at the top of the food chain that are most susceptible to extinctions (the top of the food chain will have great problems if any of the prey-preditors relationships between the plants and them is disrupted.) This mirrors what we see today: Setting aside human's role in directly killing animals (hunting/fishing) it is still the tigers, bears, sharks, eagles, tuna etc. that are most sensitive to disruptions of ecology and climate.
 

The Naked Scientists Forum

Re: What causes mass extinctions?
« Reply #12 on: 02/11/2015 18:52:03 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums