If I buy the idea that there was a (comet) impact into the ice sheet of North America at the start of the Younger Dryas, then I believe this is the scenario:
Comet explodes on ice sheet and sets North America on fire
Ice rapidly melts and floods across the continent at various spots destroying habitats
Melt water floods into the Atlantic and shuts down the Gulf Stream triggering 1400 year ice age
I've heard idea's that the cataclysm from the impact alone and subsequent wild fires could have accounted for these mega fauna extinctions. I've seen the evidence of the Mastodon carcass seemingly blown back with pelvis and leg fractures showing its death from a significant directional impact of traumatic force. I've read about the evidence of Mammoths in the melting permafrost with plants in its mouth showing evidence of a fast freeze death. But I don't need to believe that the vast majority of these animals died in one short period of trauma necessarily.
One thing in common to all these huge animals is that they all require an absolutely huge amount of food to survive. Take for example an elephant. Elephants may spend 12-18 hours a day feeding. Adult elephants can eat between 200-600 pounds of food a day. And in comparison then consider a deer that on average eats about 7 lbs of food a day. When you consider this, then even if the cataclysm only killed off small numbers of mega mammals in the actual event, when you consider the immense amount of devastation to the land that is the enormous acreage required as their food source, it becomes clear how vulnerable these huge animals really are.
And, while I'm not clear on all the varied evidence that previously supported the idea of the Blitzkrieg theory that suggests they were all hunted to extinction, I can see a scenario that supports that.
I imagine any large scale animals, simply by virtue of their size and numbers, all had to have a life of constant migration to find new sources of food as their immediate grazing areas became rapidly exhausted based on the much large demand they had. And because of this demand vulverability, all it would take to devastate that group would be one segment of their migration route to be devastated and all of a sudden, they become hungry, weak, and easy to hunt.
In other words, there could have been massive populations of mega mammals that survived the devastation of the impact period. But shortly after, these massive creatures would easily be confronted by a significant depletion of food sources, that might not otherwise be nearly as impactful to smaller animals. So its not so crazy to imagine that when human survivors of this continent wide cataclysm were fighting for their survival during the rapidly cooling climate on charred and destroyed land, the easiest food source would have been the biggest and therefore easiest to kill animals.
So maybe the Bliztkrieg theory isn't so crazy after all considering the circumstances that may have lead to that scenario playing out. And the mini versions of the rabbit, armadillo, sloth, etc that we see on the planet today are simply the surviving runts of the runts of the runts of the litter who had the singular advantage of not being as hungry by virtue of their size. Seems plausible.
Comet explodes on ice sheet and sets North America on fire
Ice rapidly melts and floods across the continent at various spots destroying habitats
Melt water floods into the Atlantic and shuts down the Gulf Stream triggering 1400 year ice age
I've heard idea's that the cataclysm from the impact alone and subsequent wild fires could have accounted for these mega fauna extinctions. I've seen the evidence of the Mastodon carcass seemingly blown back with pelvis and leg fractures showing its death from a significant directional impact of traumatic force. I've read about the evidence of Mammoths in the melting permafrost with plants in its mouth showing evidence of a fast freeze death. But I don't need to believe that the vast majority of these animals died in one short period of trauma necessarily.
One thing in common to all these huge animals is that they all require an absolutely huge amount of food to survive. Take for example an elephant. Elephants may spend 12-18 hours a day feeding. Adult elephants can eat between 200-600 pounds of food a day. And in comparison then consider a deer that on average eats about 7 lbs of food a day. When you consider this, then even if the cataclysm only killed off small numbers of mega mammals in the actual event, when you consider the immense amount of devastation to the land that is the enormous acreage required as their food source, it becomes clear how vulnerable these huge animals really are.
And, while I'm not clear on all the varied evidence that previously supported the idea of the Blitzkrieg theory that suggests they were all hunted to extinction, I can see a scenario that supports that.
I imagine any large scale animals, simply by virtue of their size and numbers, all had to have a life of constant migration to find new sources of food as their immediate grazing areas became rapidly exhausted based on the much large demand they had. And because of this demand vulverability, all it would take to devastate that group would be one segment of their migration route to be devastated and all of a sudden, they become hungry, weak, and easy to hunt.
In other words, there could have been massive populations of mega mammals that survived the devastation of the impact period. But shortly after, these massive creatures would easily be confronted by a significant depletion of food sources, that might not otherwise be nearly as impactful to smaller animals. So its not so crazy to imagine that when human survivors of this continent wide cataclysm were fighting for their survival during the rapidly cooling climate on charred and destroyed land, the easiest food source would have been the biggest and therefore easiest to kill animals.
So maybe the Bliztkrieg theory isn't so crazy after all considering the circumstances that may have lead to that scenario playing out. And the mini versions of the rabbit, armadillo, sloth, etc that we see on the planet today are simply the surviving runts of the runts of the runts of the litter who had the singular advantage of not being as hungry by virtue of their size. Seems plausible.