Why were the dinosaurs the only ones to go extinct?

[steenkh]

I have read a lot about the possible catastrophe that caused the dinosaurs to go extinct. The meteor that killed them off did not only have the direct effect of the impact, but is also supposed to have blanketed the Earth for years, causing most plants to die, and freezing down the planet for a while.

My question is, what about all those plants that need lots of light? did they not die off at the same time? Have they all evolved later from the survivors? The dinosaurs died because their food sources dried up, but lots of other animals were dependent on the same food sources: mammals, birds and reptiles all survived. How come?

Were there aquatic dinosaurs, and if so, why did they go extinct when fishes, turtles, and crocs apparently were unharmed?

 

[Bikewer]

Go to YouTube and watch the "Radiolab" segment.."Apocalyptical". All will be explained.

The extinction event, per the latest thinking was not a matter of many years of global cooling as was previously thought but rather a sudden and violent event that occurred over only a few hours.

Species that survived would have been acquatic, burrowers, cave-dwellers, etc. Plant life above ground would have been largely incinerated but roots, seeds, etc. would re-grow.

 

[Myriad]

Regardless of the details of how the extinction event played out, the simple answer is that it was not only dinosaurs that went extinct. An estimated three quarters of the extant species went extinct, including plants, mammals, insects, and aquatic species (such as ammonites that had been around for eons prior to then).

 

[Jrrarglblarg]

Paleoatmosphere is difficult to study but it appears it was far different before and after. Total air pressure and oxygen partial pressure were both higher. Actual loss mechanisms are poorly understood (I've been googling this occasionally since Google was invented and there are darn few papers written) but actual loss has been hypothesized - some of our atmosphere, highly oxygen rich, was knocked off completely by the impact.


Plants and animals that couldn't survive and adapt to a lower oxygen availability died. Ones that could survive and adapt did so.

 

[Jrrarglblarg]

Go to YouTube and watch the "Radiolab" segment.."Apocalyptical". All will be explained.

The extinction event, per the latest thinking was not a matter of many years of global cooling as was previously thought but rather a sudden and violent event that occurred over only a few hours.

Species that survived would have been acquatic, burrowers, cave-dwellers, etc. Plant life above ground would have been largely incinerated but roots, seeds, etc. would re-grow.

This presentation of theory is well produced does not appear to be well supported. I've listened to this story a couple times.

 

[Damien Evans]

They weren't (and they didn't, the buggers wake me up with their singing from time to time). Mososaurs, Plesiosaurs, Pliosaurs, Ammonites, Pterosaurs and many other orders of both plant and animal life were wiped out in addition to the Non-Avian Dinosaurs.

https://en.wikipedia.org/wiki/Cretaceous–Paleogene_extinction_event

 

[steenkh]

Thank you. There is much here that I was not aware of.

I am not convinced of the theory that only above-ground species would be hit, because first of all I have often heard that the actual extinction took place over many hundred thousands of years, and secondly that aquatic species should all have survived if they were far enough from the impact site.

 

[MikeG]

Thank you. There is much here that I was not aware of.

I am not convinced of the theory that only above-ground species would be hit, because first of all I have often heard that the actual extinction took place over many hundred thousands of years, and secondly that aquatic species should all have survived if they were far enough from the impact site.

That is a very long way from the current thinking.

 

[Cainkane1]

Dinosaurs were surface dwellers whereas burrowing mammals and other protected animals were not. When the catastrophes occurred the extinction event mainly included just those creatures who were exposed the most to the event.

 

[Jrrarglblarg]

That is a very long way from the current thinking.

Yes. Even with a skeptical view of the "apocalyptical" theory, the atmospheric conditions worldwide changed sufficiently to cause mass extinctions within the first hours, months and years.

 

[Segnosaur]

I have read a lot about the possible catastrophe that caused the dinosaurs to go extinct.

They went extinct? News to me.

I have a couple of dinosaurs related to the theropods at home right now... granted, they're totally covered with feathers now, and have bills instead of teeth. You might know them as 'birds', which are often classified as dinosaurs.

The meteor that killed them off did not only have the direct effect of the impact, but is also supposed to have blanketed the Earth for years,

There is also a theory that the impact sent tons of debris into space, which, over the next few hours, would have reentered the atmosphere all over the earth and heated things up all around the world (not just local to the impact).

My question is, what about all those plants that need lots of light? did they not die off at the same time? Have they all evolved later from the survivors?

Probably yes. You would have had seeds underground, and some smaller plants in sheltered areas to maintain at least some species.

The dinosaurs died because their food sources dried up, but lots of other animals were dependent on the same food sources: mammals, birds and reptiles all survived. How come?

The animals that would have survived were: 1) able to burrow or go to water temporarily to avoid the initial heat from the impact and the debris reentering the atmosphere, and 2) small enough to require minimal food, so they could survive for the few decades on whatever plants were able to survive, until the environment started to return to normal.

Were there aquatic dinosaurs, and if so, why did they go extinct when fishes, turtles, and crocs apparently were unharmed?

There were no "aquatic dinosaurs", but there were large marine reptiles (like plesiosaurs) that are often mistakenly considered dinosaurs.

The asteroid would have affected the food chain in the seas as well... since the marine reptiles were larger than (for example) crocs, they would have been more affected by changes in food sources. A croc is smaller, and will better able to find food to survive.

that aquatic species should all have survived if they were far enough from the impact site.

Well, as I pointed out, the impact possibly threw debris into space, which would have come down all over the planet, heating up the atmosphere upon re-entry. Water was going to heat up everywhere, not just near the impact.

 

[Giordano]

Regardless of the details of how the extinction event played out, the simple answer is that it was not only dinosaurs that went extinct. An estimated three quarters of the extant species went extinct, including plants, mammals, insects, and aquatic species (such as ammonites that had been around for eons prior to then).

^This.

 

[Gawdzilla Sama]

"Nuclear winter" or no "Nuclear winter"?

 

[Giordano]

They weren't (and they didn't, the buggers wake me up with their singing from time to time). Mososaurs, Plesiosaurs, Pliosaurs, Ammonites, Pterosaurs and many other orders of both plant and animal life were wiped out in addition to the Non-Avian Dinosaurs.

https://en.wikipedia.org/wiki/Cretaceous–Paleogene_extinction_event

^ This, too! Some types of dinosaurs were wiped out. Others continued to evolve and did quite well.

 

[ceptimus]

It surprises me that frogs and other amphibians managed to survive an extinction event that wiped out so many species - I would have thought that amphibians would be more susceptible to extinction than the smaller varieties of dinosaur. I wonder how the amphibians managed it?

 

[Gawdzilla Sama]

It surprises me that frogs and other amphibians managed to survive an extinction event that wiped out so many species - I would have thought that amphibians would be more susceptible to extinction than the smaller varieties of dinosaur. I wonder how the amphibians managed it?

They can hibernate.

 

[Segnosaur]

It surprises me that frogs and other amphibians managed to survive an extinction event that wiped out so many species - I would have thought that amphibians would be more susceptible to extinction than the smaller varieties of dinosaur. I wonder how the amphibians managed it?

They can hibernate.

More likely....
- They can spend a significant time in the water, avoiding severe heat from the asteroid impact and any debris re-entering the atmosphere. I don't think smaller dinosaurs were necessarily aquatic, so they'd be trapped on land, in the open
- They were smaller, so would have had lower food requirements than the smaller dinosaurs. (If food is scarce, you can maintain a larger breeding population and more genetic diversity if each individual requires fewer calories.)

 

[Gawdzilla Sama]

More likely....
- They can spend a significant time in the water, avoiding severe heat from the asteroid impact and any debris re-entering the atmosphere. I don't think smaller dinosaurs were necessarily aquatic, so they'd be trapped on land, in the open
- They were smaller, so would have had lower food requirements than the smaller dinosaurs. (If food is scarce, you can maintain a larger breeding population and more genetic diversity if each individual requires fewer calories.)

Crocs can hibernate up to three years. If conditions are conductive to feeding they tend to bunker down. This leads me to think that the same thing happened back then.

 

[macdoc]

Realize as well that current evidence is that subsequent basalt flows were triggered by the impact so it really depends on what range of time you want to consider extinction event.

Did dinosaur-killing asteroid trigger largest lava flows on Earth?

By Robert Sanders | APRIL 30, 2015

The asteroid that slammed into the ocean off Mexico 66 million years ago and killed off the dinosaurs probably rang the Earth like a bell, triggering volcanic eruptions around the globe that may have contributed to the devastation, according to a team of UC Berkeley geophysicists.

I was conversing with one of the scientists that discovered the crater and mentioned it always bugged me for years that there "should" be a link between the impact of that size and lava flow....I used the phrase the bolide "rang the earth like a bell" .....and any impact would stress weak parts of the crust....
He emailed me back and said watch for a paper next month ....sure enough ....the author used the same anaolgy and has some good evidence and thesis.

Also interesting out of New Jersey ...a dinosaur extinction boneyard.

Behind a Shopping Center in New Jersey, Signs of a Mass Extinction
By KENNETH CHANGJAN. 4, 2016

MANTUA TOWNSHIP, N.J. — Behind a Lowe’s home improvement store here, scientists are methodically scraping and sifting through a quarry pit that may contain unique insights to the mass extinction that eliminated the dinosaurs.
Back then, about 66 million years ago, the oceans were higher, and this part of southern New Jersey was a shallow sea, 10 to 15 miles offshore from an ancient mountain range that rose from the water. Today’s quarry pit was once the sea bottom, and one particular layer about 40 feet beneath the surface contains a bounty of fossils.

more

http://www.nytimes.com/2016/01/05/s...in-new-jersey-signs-of-a-mass-extinction.html

You really have to decide what the time frame of the extinction event to consider as the knock effects went on for a very long time...those lava flows for millions of years....are they also part of the event??? as that altered the earth's weather and biomes dramatically over time but the time frame was long enough for evolution to sort things as well.

 

[Segnosaur]

Re: Why amphibians survived and small dinos did not...

More likely....
- They can spend a significant time in the water, avoiding severe heat from the asteroid impact and any debris re-entering the atmosphere. I don't think smaller dinosaurs were necessarily aquatic, so they'd be trapped on land, in the open
- They were smaller, so would have had lower food requirements than the smaller dinosaurs. (If food is scarce, you can maintain a larger breeding population and more genetic diversity if each individual requires fewer calories.)

Crocs can hibernate up to three years. If conditions are conductive to feeding they tend to bunker down. This leads me to think that the same thing happened back then.

Another difference between crocs and small dinos... they can eat fish.

While many marine species (including some fish) went extinct, some survived. Being able to eat fish would have given them more sources of food (something a terrestrial dinosaur would not have had access to.)

Plus, there is also the fact that Crocs spend much of their time in water; this would help them survive the intense heat globally after the impact.