6 ms·

Modern snakes evolved from few survivors of dino-killing asteroid

53 points by wombatmobile 5y ago

jjcon 5y ago
> A new study suggests that all living snakes evolved from a handful of species that survived the giant asteroid impact that wiped out the dinosaurs and most other living things at the end of the Cretaceous. I mean... didnt everything that is around today evolve from species that weren't wiped out?
- eesmith 5y ago
  I think the question is more did a "handful" of snake species survive or did "many" survive? That is, when did the diversification we see in modern snakes start? From the paper: > Historically, squamates were believed to have experienced minimal extinction at the K-Pg boundary ... So far, molecular divergence time analyses of snakes recover conflicting patterns ... Given this uncertainty, we attempted to improve our understanding of the timescale of crown snake diversification and the methodological factors that affect these inferences. ... Our results suggest a potential diversification of snakes near the time of the K-Pg transition.
  - erhk 5y ago
    Is this possible evidence for a food chain collapse at this time?
    - enkid 5y ago
      I don't think there's any question that the food chain collapsed and that's what caused most of the animal extinctions.
- simonh 5y ago
  I tell my kids that if they don't give me grandchildren, they'll be breaking a 4 billion year record of 100% reproductive success. Every single one of their ancestors, back to the first DNA molecule succeeded at having offspring. Let's not break that record. No pressure.
  - psychoslave 5y ago
    Have you tried to forbid them to have kids?
    - simonh 5y ago
      Reverse psychology works great when they're toddlers, but they soon catch on to it.
      - erhk 5y ago
        Try telling them that youre indifferent. Maybe a lateral angle will work
      - hyperpallium2 5y ago
        Huh! Well, I'm going to try it anyway!
      - bbarnett 5y ago
        Which is why reverse-reverse psychology is used.
  - koolba 5y ago
    It’s even more specific! You can tell a son that all their male ancestors had a son! And you can tell a daughter that all their female ancestors had a daughter! No pressure indeed!
    - perpetualpatzer 5y ago
      > You can tell a son that all their male ancestors had a son This seems off... by counterexample, my grandfather had no sons, but three daughters (one being my mother).
      - frankbreetz 5y ago
        Your mother is not a male ancestor. Parent was just saying there is a line of all males for men and all females for women.
- kjaftaedi 5y ago
  Bacteria species, sure, but having full on land animals survive an event like that is worthy of note. This discovery channel video might help put things in perspective: https://youtu.be/bU1QPtOZQZU https://youtu.be/bU1QPtOZQZU
jimmyed 5y ago
Wait, aren't we planning to make sure everyone believes the asteroid story first before building additional stories on top of it?
- codefreakxff 5y ago
  Can’t tell if that’s sarcasm There’s no way to make sure everyone believes anything. So. No.
  - Out_of_Characte 5y ago
    It wasn't. There's definitely an extinction-level event near the rumored asteroid but the evidence is not overwhelming. asteroid hits are very very time specific one second you're fine, the next an asteroid is supposedly killing more than half of all life on the planet. yet 'some' reduction in species is rumored to have happened before the impact which negates the asteroid theory
    - eesmith 5y ago
      Which "rumored asteroid" do you refer to? You don't think an asteroid caused the Chicxulub crater? There's an awful lot of evidence in support of it. How else do you explain a 180 km crater, the iridium layer, the shocked stone, the ejecta spherules, etc? There are several relevant asteroid theories. Since you say "negate", I assume you mean the theory that the asteroid was the sole cause of the K-Pg extinction event? Shrug. Okay. Perhaps there were multiple causes; volcanism, marine regression, and extraterrestrial impact. https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event#Multiple_causes https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e... . I don't think anyone would be severely upset should this prove true. That's still an asteroid theory.
    - AbrahamParangi 5y ago
      You can also get “evidence” of species reduction pre-impact with archeological error- by accidentally classing post impact material as pre.
- 5y ago
yesenadam 5y ago
Link to the (online) paper Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction https://www.nature.com/articles/s41467-021-25136-y https://www.nature.com/articles/s41467-021-25136-y p.s. Werner Herzog visits Chicxulub in his latest documentary, about meteors and comets and their effect on human cultures, Fireball: Visitors from Darker Worlds, which I thought was pretty great.
netcan 5y ago
IIRC, this was already the standard story of snake evolution. I believe the remaining mystery revolves around which lineage they evolved from. Skinks, monitors and I believe Plesiosaurs are proposed as possibilities... At present, there are multiple lineages of non-snake, legless lizards. That basic body plan is relatively abundant, probably was then too. One of these lineages started to diversify into snakes after KT. Large fauna extinctions probably made small prey more abundant, so it's a good time to be a snake. A lot of snakes are mammal specialists, which also succeeded after KT. Snakes may have started to proliferate in response to the post KT abundance small burrowing mammals.
- pfdietz 5y ago
  There are plenty of weird legless tetrapods back as far as the Carboniferous. It's an ancient niche.
- nickik 5y ago
  But didn't snakes evolve from something with legs? There are a number of snakes, specially historically with legs and some where the leg bones are still there. Legless lizards and snakes some to convergent evolution. But its of course possible that other legless lizards existed before that.
  - netcan 5y ago
    There are modern species of snakes with vestigial legs today, pythons, boas... Leglessness in lizards not very uncommon. It evolves regularly, before and after the snake lineage likely originates. One species of such creatures became the ancestor of snakes. I think (not an expert) that the lineage of that creature is still speculative... with a still-wide range of candidates. Not sure if Plesiosaurs are still a contender, but if it is then it gives Plesiosaurs the same relationship to snakes that birds have to dinosaurs.
yawaworht1978 5y ago
Birds are said to be the closest to dinosaurs, followed by crocodiles, alligators and reptiles. Next in line are chicken, turtles and parrots. Crazy to imagine how homo sapiens evolved from that selection. Other sources say crocodiles and alligators bare the closest, their fossils haven't changed in 70 million years, which is before the big extinction date, means they looked the same then and now. Another interesting thing, if true is, that sharks are older than any dinosaurs, other sources say today's sharks descended from relatives that swam alongside dinosaurs in prehistoric times. Haven't looked too closely and am no expert on the matter.
- nickik 5y ago
  Are chickens not birds?
  - margalabargala 5y ago
    Only in the same way a parrot is
- nerdponx 5y ago
  I was under the impression that some small early mammal species would have survived, and later diversified into the wide range of mammals we have today, including primates like us.
- Tagbert 5y ago
  All lineages go back to the time of dinosaurs and earlier. (Ultimately they all appear to converge on the last common ancestor) Any species tend to only last for 1-2 million years. If they don’t go extinct, they give rise to one more more descendant species. This produces a chain of ancestry where species give birth to more species. Sharks, as a group, certainly arose before the time of dinosaurs. The current species of sharks evolved recently from earlier species of sharks. There were multiple groups of reptiles prior to the time of the dinosaurs. Some of those reptiles produced descendants that later became mammals. Some of those reptiles produced descendants that became crocodiles, turtles, and dinosaurs. Humans, as mammals descended from those early mammals that first appeared before the “age of dinosaurs”. Mammals lived alongside dinosaurs for hundreds of millions of years. When the dinosaurs went extinct, the global disruption that cause that extinction removed most of the species living at that time. The survivors then found room to evolve into new niches in the ecologies as those ecologies recovered. Reptiles like the ancestors of modern crocodiles survived. Birds were the only group of dinosaur to survive and chickens and parrots are modern examples of that bird group. The mammals that survived evolved into newly opened up ecological niches and many lineages branched out from those survivors. The primates, including humans, were one such group. I hope that this, high level summary, helps clear things up a little for you.
nikkinana 5y ago
Bullshit. Just bullshit.

53 points by wombatmobile 5y ago

> A new study suggests that all living snakes evolved from a handful of species that survived the giant asteroid impact that wiped out the dinosaurs and most other living things at the end of the Cretaceous. I mean... didnt everything that is around today evolve from species that weren't wiped out?

eesmith 5y ago
I think the question is more did a "handful" of snake species survive or did "many" survive? That is, when did the diversification we see in modern snakes start? From the paper: > Historically, squamates were believed to have experienced minimal extinction at the K-Pg boundary ... So far, molecular divergence time analyses of snakes recover conflicting patterns ... Given this uncertainty, we attempted to improve our understanding of the timescale of crown snake diversification and the methodological factors that affect these inferences. ... Our results suggest a potential diversification of snakes near the time of the K-Pg transition.
- erhk 5y ago
  Is this possible evidence for a food chain collapse at this time?
  - enkid 5y ago
    I don't think there's any question that the food chain collapsed and that's what caused most of the animal extinctions.
simonh 5y ago
I tell my kids that if they don't give me grandchildren, they'll be breaking a 4 billion year record of 100% reproductive success. Every single one of their ancestors, back to the first DNA molecule succeeded at having offspring. Let's not break that record. No pressure.
- psychoslave 5y ago
  Have you tried to forbid them to have kids?
  - simonh 5y ago
    Reverse psychology works great when they're toddlers, but they soon catch on to it.
    - erhk 5y ago
      Try telling them that youre indifferent. Maybe a lateral angle will work
    - hyperpallium2 5y ago
      Huh! Well, I'm going to try it anyway!
    - bbarnett 5y ago
      Which is why reverse-reverse psychology is used.
- koolba 5y ago
  It’s even more specific! You can tell a son that all their male ancestors had a son! And you can tell a daughter that all their female ancestors had a daughter! No pressure indeed!
  - perpetualpatzer 5y ago
    > You can tell a son that all their male ancestors had a son This seems off... by counterexample, my grandfather had no sons, but three daughters (one being my mother).
    - frankbreetz 5y ago
      Your mother is not a male ancestor. Parent was just saying there is a line of all males for men and all females for women.
kjaftaedi 5y ago
Bacteria species, sure, but having full on land animals survive an event like that is worthy of note. This discovery channel video might help put things in perspective: https://youtu.be/bU1QPtOZQZU https://youtu.be/bU1QPtOZQZU

jimmyed 5y ago

Wait, aren't we planning to make sure everyone believes the asteroid story first before building additional stories on top of it?

codefreakxff 5y ago
Can’t tell if that’s sarcasm There’s no way to make sure everyone believes anything. So. No.
- Out_of_Characte 5y ago
  It wasn't. There's definitely an extinction-level event near the rumored asteroid but the evidence is not overwhelming. asteroid hits are very very time specific one second you're fine, the next an asteroid is supposedly killing more than half of all life on the planet. yet 'some' reduction in species is rumored to have happened before the impact which negates the asteroid theory
  - eesmith 5y ago
    Which "rumored asteroid" do you refer to? You don't think an asteroid caused the Chicxulub crater? There's an awful lot of evidence in support of it. How else do you explain a 180 km crater, the iridium layer, the shocked stone, the ejecta spherules, etc? There are several relevant asteroid theories. Since you say "negate", I assume you mean the theory that the asteroid was the sole cause of the K-Pg extinction event? Shrug. Okay. Perhaps there were multiple causes; volcanism, marine regression, and extraterrestrial impact. https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event#Multiple_causes https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e... . I don't think anyone would be severely upset should this prove true. That's still an asteroid theory.
  - AbrahamParangi 5y ago
    You can also get “evidence” of species reduction pre-impact with archeological error- by accidentally classing post impact material as pre.
5y ago

yesenadam 5y ago

Link to the (online) paper Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction https://www.nature.com/articles/s41467-021-25136-y https://www.nature.com/articles/s41467-021-25136-y p.s. Werner Herzog visits Chicxulub in his latest documentary, about meteors and comets and their effect on human cultures, Fireball: Visitors from Darker Worlds, which I thought was pretty great.

netcan 5y ago

IIRC, this was already the standard story of snake evolution. I believe the remaining mystery revolves around which lineage they evolved from. Skinks, monitors and I believe Plesiosaurs are proposed as possibilities... At present, there are multiple lineages of non-snake, legless lizards. That basic body plan is relatively abundant, probably was then too. One of these lineages started to diversify into snakes after KT. Large fauna extinctions probably made small prey more abundant, so it's a good time to be a snake. A lot of snakes are mammal specialists, which also succeeded after KT. Snakes may have started to proliferate in response to the post KT abundance small burrowing mammals.

pfdietz 5y ago
There are plenty of weird legless tetrapods back as far as the Carboniferous. It's an ancient niche.
nickik 5y ago
But didn't snakes evolve from something with legs? There are a number of snakes, specially historically with legs and some where the leg bones are still there. Legless lizards and snakes some to convergent evolution. But its of course possible that other legless lizards existed before that.
- netcan 5y ago
  There are modern species of snakes with vestigial legs today, pythons, boas... Leglessness in lizards not very uncommon. It evolves regularly, before and after the snake lineage likely originates. One species of such creatures became the ancestor of snakes. I think (not an expert) that the lineage of that creature is still speculative... with a still-wide range of candidates. Not sure if Plesiosaurs are still a contender, but if it is then it gives Plesiosaurs the same relationship to snakes that birds have to dinosaurs.

yawaworht1978 5y ago

Birds are said to be the closest to dinosaurs, followed by crocodiles, alligators and reptiles. Next in line are chicken, turtles and parrots. Crazy to imagine how homo sapiens evolved from that selection. Other sources say crocodiles and alligators bare the closest, their fossils haven't changed in 70 million years, which is before the big extinction date, means they looked the same then and now. Another interesting thing, if true is, that sharks are older than any dinosaurs, other sources say today's sharks descended from relatives that swam alongside dinosaurs in prehistoric times. Haven't looked too closely and am no expert on the matter.

nickik 5y ago
Are chickens not birds?
- margalabargala 5y ago
  Only in the same way a parrot is
nerdponx 5y ago
I was under the impression that some small early mammal species would have survived, and later diversified into the wide range of mammals we have today, including primates like us.
Tagbert 5y ago
All lineages go back to the time of dinosaurs and earlier. (Ultimately they all appear to converge on the last common ancestor) Any species tend to only last for 1-2 million years. If they don’t go extinct, they give rise to one more more descendant species. This produces a chain of ancestry where species give birth to more species. Sharks, as a group, certainly arose before the time of dinosaurs. The current species of sharks evolved recently from earlier species of sharks. There were multiple groups of reptiles prior to the time of the dinosaurs. Some of those reptiles produced descendants that later became mammals. Some of those reptiles produced descendants that became crocodiles, turtles, and dinosaurs. Humans, as mammals descended from those early mammals that first appeared before the “age of dinosaurs”. Mammals lived alongside dinosaurs for hundreds of millions of years. When the dinosaurs went extinct, the global disruption that cause that extinction removed most of the species living at that time. The survivors then found room to evolve into new niches in the ecologies as those ecologies recovered. Reptiles like the ancestors of modern crocodiles survived. Birds were the only group of dinosaur to survive and chickens and parrots are modern examples of that bird group. The mammals that survived evolved into newly opened up ecological niches and many lineages branched out from those survivors. The primates, including humans, were one such group. I hope that this, high level summary, helps clear things up a little for you.

nikkinana 5y ago

Bullshit. Just bullshit.