4 ms·

Scientists find remains of huge ancient herbivore

54 points by dnetesn 8y ago

burtonator 8y ago
I was hoping this was from the pleistocene... for some reason I'm fascinated that animals like the Giant Sloth existed only 15k years ago.
- RidingPegasus 8y ago
  Shame we had to kill them all. Not to judge though, modern day humans seem to have upped the ante.
- craftyguy 8y ago
  One species of Mammoth existed until about 2.4k years ago[0]. 0. https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/2015 https://journals.uair.arizona.edu/index.php/radiocarbon/arti...
  - richardknop 8y ago
    Is it known what killed off mammoths? Was it human hunters killing them of or some natural cause? Something like climate change that caused them to not have enough food?
    - dotancohen 8y ago
      Consider that mammoth populations survived past the ice age in places that humans did not live, mostly islands north of Siberia. Now consider that those mammoths were quickly extinguished as soon as humans touched foot on those islands.
alejohausner 8y ago
This was a giant mammal that coexisted with dinosaurs. I had always thought that mammals appeared during the age of dinosaurs, but they were all tiny mouse-sized mammals.
- gus_massa 8y ago
  They were not mammals. They were more related to the ancestors of mammals than to the dinosaurs. The article calls them "mammal-like reptiles". You can see in this graph when their ancestors an our ancestor split. https://en.wikipedia.org/wiki/Evolution_of_mammals#Therapsid_family_tree https://en.wikipedia.org/wiki/Evolution_of_mammals#Therapsid... It's the third branching in this graph. For comparison, see the graph in the same page https://en.wikipedia.org/wiki/Evolution_of_mammals#The_ancestry_of_mammals https://en.wikipedia.org/wiki/Evolution_of_mammals#The_ances... . Here is the split between reptiles/dinosaurs/birds and the ancestors of mammals in the second branching. (You can "glue" the other graphic in the lowest branch of this graphic, but I'm not sure if they have a comparable level of detail.)
- Scriptor 8y ago
  Not quite mammals but mammal-like reptiles. They're related to mammals but not our direct ancestors, more like aunts and uncles in the evolutionary family tree.
- gnulinux 8y ago
  Imagine the latest common ancestor of all mammals i.e. the last individual that all mammals are related to. The species in the article would not be an N-th degree child of this individual, but it would be an N-th degree cousin of this individual.
- Arnt 8y ago
  The ones that survived the Giant Frying were mouse-sized, but bigger ones existed before then, even though they might look mouse-sized to a passing brontosaurus. (On the Giant Frying: http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/robertson2004.pdf http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/rob... )
  - nerdponx 8y ago
    There's nothing quite like a well-written scientific paper. This isn't my field at all but I enjoyed reading this immensely.
- 8y ago
calibas 8y ago
It's barely been a week since the existence of a whole new kingdom of life was confirmed (https://www.nature.com/articles/s41586-018-0708-8 https://www.nature.com/articles/s41586-018-0708-8), certainly an exciting time for biologists. Must be tough even keeping up with the latest developments.
- lake99 8y ago
  If we're talking about single-celled organisms, it's quite possible that there are hundreds of "kingdoms" living among us. The trend to abandon the Linnaean classificaton is quite prominent among those analyzing macroscopic organisms. But among those working with microscopic organisms, I've come across some of them abandoning the tree of life itself. My mind was blown when I watched the discussion between Dawkins and Venter. https://en.wikipedia.org/wiki/Kingdom_(biology)#Summary https://en.wikipedia.org/wiki/Kingdom_(biology)#Summary https://evolutionnews.org/2011/03/venter_vs_dawkins_on_the_tree_/ https://evolutionnews.org/2011/03/venter_vs_dawkins_on_the_t...
  - gus_massa 8y ago
    The last article is extremely misleading. It is true that there are variations of the genetic code. (Wikipedia says 32, including the usual genetic code that we have. https://en.wikipedia.org/wiki/List_of_genetic_codes https://en.wikipedia.org/wiki/List_of_genetic_codes ) But the variations are minor, each has only a few changes from the most used code. For example mitochondria (that are also "we") have only 4 changes out of 64 https://en.wikipedia.org/wiki/Vertebrate_mitochondrial_code https://en.wikipedia.org/wiki/Vertebrate_mitochondrial_code . So the easiest explanation is that the genetic code evolved from a genetic code ancestor. Moreover, our genetic code is probably not the original code. IIRC the guess is that initially it has only 16 slots. These slots are visible as some big squares in the curren table, but some of these slots are divided now. Most of the time a change in the genetic code is catastrophic, so it's not easy to change it. But it may be possible if it changes one aminoacidic by a similar one, or if you are extremely lucky. In the table all the changes are in mitochondria/bacteria/archaea, not in animals or plants. Since they are small, they have bigger numbers and faster generations, so they have a bigger chance of a lucky random mutation. In particular, 12 of the 32 genetic codes in the list are variations in mitochondrial code. All the mitocondria are very similar. The incorporation of mitocondrial was a very strange lucky event. Nobody think that the 12 variants of mitochondria appear independently, each one in its own tree of life, and were absorbed later independently.
mcguire 8y ago
Looks like a giant guinea pig. Nature never ceases to amaze me.

54 points by dnetesn 8y ago

I was hoping this was from the pleistocene... for some reason I'm fascinated that animals like the Giant Sloth existed only 15k years ago.

RidingPegasus 8y ago
Shame we had to kill them all. Not to judge though, modern day humans seem to have upped the ante.
craftyguy 8y ago
One species of Mammoth existed until about 2.4k years ago[0]. 0. https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/2015 https://journals.uair.arizona.edu/index.php/radiocarbon/arti...
- richardknop 8y ago
  Is it known what killed off mammoths? Was it human hunters killing them of or some natural cause? Something like climate change that caused them to not have enough food?
  - dotancohen 8y ago
    Consider that mammoth populations survived past the ice age in places that humans did not live, mostly islands north of Siberia. Now consider that those mammoths were quickly extinguished as soon as humans touched foot on those islands.

alejohausner 8y ago

This was a giant mammal that coexisted with dinosaurs. I had always thought that mammals appeared during the age of dinosaurs, but they were all tiny mouse-sized mammals.

gus_massa 8y ago
They were not mammals. They were more related to the ancestors of mammals than to the dinosaurs. The article calls them "mammal-like reptiles". You can see in this graph when their ancestors an our ancestor split. https://en.wikipedia.org/wiki/Evolution_of_mammals#Therapsid_family_tree https://en.wikipedia.org/wiki/Evolution_of_mammals#Therapsid... It's the third branching in this graph. For comparison, see the graph in the same page https://en.wikipedia.org/wiki/Evolution_of_mammals#The_ancestry_of_mammals https://en.wikipedia.org/wiki/Evolution_of_mammals#The_ances... . Here is the split between reptiles/dinosaurs/birds and the ancestors of mammals in the second branching. (You can "glue" the other graphic in the lowest branch of this graphic, but I'm not sure if they have a comparable level of detail.)
Scriptor 8y ago
Not quite mammals but mammal-like reptiles. They're related to mammals but not our direct ancestors, more like aunts and uncles in the evolutionary family tree.
gnulinux 8y ago
Imagine the latest common ancestor of all mammals i.e. the last individual that all mammals are related to. The species in the article would not be an N-th degree child of this individual, but it would be an N-th degree cousin of this individual.
Arnt 8y ago
The ones that survived the Giant Frying were mouse-sized, but bigger ones existed before then, even though they might look mouse-sized to a passing brontosaurus. (On the Giant Frying: http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/robertson2004.pdf http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/rob... )
- nerdponx 8y ago
  There's nothing quite like a well-written scientific paper. This isn't my field at all but I enjoyed reading this immensely.
8y ago

calibas 8y ago

It's barely been a week since the existence of a whole new kingdom of life was confirmed (https://www.nature.com/articles/s41586-018-0708-8 https://www.nature.com/articles/s41586-018-0708-8), certainly an exciting time for biologists. Must be tough even keeping up with the latest developments.

lake99 8y ago
If we're talking about single-celled organisms, it's quite possible that there are hundreds of "kingdoms" living among us. The trend to abandon the Linnaean classificaton is quite prominent among those analyzing macroscopic organisms. But among those working with microscopic organisms, I've come across some of them abandoning the tree of life itself. My mind was blown when I watched the discussion between Dawkins and Venter. https://en.wikipedia.org/wiki/Kingdom_(biology)#Summary https://en.wikipedia.org/wiki/Kingdom_(biology)#Summary https://evolutionnews.org/2011/03/venter_vs_dawkins_on_the_tree_/ https://evolutionnews.org/2011/03/venter_vs_dawkins_on_the_t...
- gus_massa 8y ago
  The last article is extremely misleading. It is true that there are variations of the genetic code. (Wikipedia says 32, including the usual genetic code that we have. https://en.wikipedia.org/wiki/List_of_genetic_codes https://en.wikipedia.org/wiki/List_of_genetic_codes ) But the variations are minor, each has only a few changes from the most used code. For example mitochondria (that are also "we") have only 4 changes out of 64 https://en.wikipedia.org/wiki/Vertebrate_mitochondrial_code https://en.wikipedia.org/wiki/Vertebrate_mitochondrial_code . So the easiest explanation is that the genetic code evolved from a genetic code ancestor. Moreover, our genetic code is probably not the original code. IIRC the guess is that initially it has only 16 slots. These slots are visible as some big squares in the curren table, but some of these slots are divided now. Most of the time a change in the genetic code is catastrophic, so it's not easy to change it. But it may be possible if it changes one aminoacidic by a similar one, or if you are extremely lucky. In the table all the changes are in mitochondria/bacteria/archaea, not in animals or plants. Since they are small, they have bigger numbers and faster generations, so they have a bigger chance of a lucky random mutation. In particular, 12 of the 32 genetic codes in the list are variations in mitochondrial code. All the mitocondria are very similar. The incorporation of mitocondrial was a very strange lucky event. Nobody think that the 12 variants of mitochondria appear independently, each one in its own tree of life, and were absorbed later independently.

mcguire 8y ago

Looks like a giant guinea pig. Nature never ceases to amaze me.