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Modern snakes evolved from few survivors of dino-killing asteroid (miragenews.com)
53 points by wombatmobile 12 days ago | hide | past | favorite | 49 comments

> 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?

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.

A few decades ago humans were going to smother the planet with people. Now we're dying out. Come on, there are billions of us. Demographic trends will come and go, but for now shedding a few billion people organically over the next century or so would be no bad thing.

Have you tried to forbid them to have kids?

Reverse psychology works great when they're toddlers, but they soon catch on to it.

Huh! Well, I'm going to try it anyway!

Try telling them that youre indifferent. Maybe a lateral angle will work

Which is why reverse-reverse psychology is used.

well, the ancestor lineage also was able to take steps to accomplish that goal.

Your kids can tell you that if you don't provide an arranged marriage partner for them, it'd be your fault that they couldn't find a partner and thus reproduce!

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!

> 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).

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.

No, but the maternal grandfather is still a male ancestor. Parent said "all male ancestors had a son", which is not true. The true statement is that, for any generation of ancestors, at least one had a son.

I agree that's what he probably intended, but that's definitely not what he said.

Yes that is what I intended. The line up the father side for the boys and the mother side for the girls.

There is an unbroken line of males having males and females having females, but not every male ancestor had a son and not every female had a daughter. Every ancestor had a father and mother, but it doesn't work in reverse.

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.

Is this possible evidence for a food chain collapse at this time?

I don't think there's any question that the food chain collapsed and that's what caused most of the animal extinctions.

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:


Link to the (online) paper Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction


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.

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.

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.

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.

There are plenty of weird legless tetrapods back as far as the Carboniferous. It's an ancient niche.

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

I don't know why your comment has gotten downvoted so much. Astroid impact proponents present their view as rock solid but the reality is there are holes in the evidence (like population decline prior to impact) and credible alternative theories like massive volcanic activity.

The entire field of palentology seems like an acrimonous mess.


> I don't know why your comment has gotten downvoted so much.

I did not downvote (I try to assume best intent), but to me the tone of the comment reads more like "make sure everyone falls for the first lie" rather than "this theory is not yet totally proven". The phrase "(make) everyone believe" is just to overused by conspiracy theorists these days and 'prove' or 'find more evidence' would fit much better for a scientific discussion.


What do the Q have to do with this?

Meteor impacts can't melt steel beams. Bush did Chucxulub.

Why not both asteroids and the Deccan Traps?

Given it was spewing out massive amount of gases for millions of years prior to the Yucatan impact, I don't see any conflict between the population declines prior and the Yucatan impact finishing it off.

Or the impact itself amplifying the erruption(s) and impacts.

The seismic ground shock would have been felt around the world. At the antipodes, depending on the model chosen, there might have been from 4--30m of vertical displacement.


AFAIU, this would have been nearer Australia than India, though I'm not certain, and the Indian plate and Deccan Traps could plausibly have been within or near the enhanced antipodal seismic zone.

> Astroid impact proponents present their view as rock solid but the reality is there are holes in the evidence […]

I…really thought this was going to be a joke post based on this sentence!

There is no contradiction: from a systems point of view, a single event may not have been enough to have such a massive impact. The fact is, we're not seeing a single non avian dinosaur in the fossil record after the event. Same for entire other genuses. If the system hadn't already been destabilized beforehand, we probably would have seen remnants lingering for a couple million years or more. Instead, we see a crystal clear cut off date.

There is no real doubt that the Chicxulub bolide impact occurred, caused shockwaves and tsunamis, and ejected a bunch of hot material.

Eg, quoting https://www.pnas.org/content/pnas/116/17/8190.full.pdf, "The KPg boundary ... is distinguished by impact-related debris, including a distinctive iridium anomaly, shocked minerals, ejecta spherules, microkrystites, nanodiamonds, and occasionally unaltered impact-melt glass."

(That paper is about the amazing Tanis site, where a ∼1.3-m-thick deposit records events which occurred minutes to hours after the impact, and includes pterosaur fossils and perhaps dinosaur feathers and a hip bone. https://en.wikipedia.org/wiki/Tanis_(fossil_site) )

Even if non-avian dinosaurs were killed off earlier by consequences of the Deccan traps, we know modern snakes survived, so their ancestors must have survived the Chicxulub impact.

Both - or a combination of even more incidents could be plausible. I guess it would be similar to a disastrous plane accident; usually it's not caused by a single failure, but a multitude of failures with a resulting cascade effect.

The extinction occurred exactly at the impact boundary. If you are denying a casual link then you are proposing an extreme coincidence.

The link you give is to a story about a notorious gadfly. She has not convinced the field, far from it. I get the impression there is little patience for the reasoning she has presented in her papers on the subject.

The fact that we're not 100% sure of a theory does not prevent us from building upon it. See, for example, all the work built on the basis of dark matter and dark energy. Proving this dependent theory might even help solidify the original one.

The first paragraph of the Introduction of the actual paper discusses "the asteroid story" and the evidence for it and has a dozen links to papers on the subject.


Can’t tell if that’s sarcasm

There’s no way to make sure everyone believes anything. So. No.

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

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_e... . I don't think anyone would be severely upset should this prove true.

That's still an asteroid theory.

You can also get “evidence” of species reduction pre-impact with archeological error- by accidentally classing post impact material as pre.

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.

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.

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.

Are chickens not birds?

Only in the same way a parrot is

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