Modern snakes evolved from few survivors of dino-killing asteroid
miragenews.com
miragenews.com
I mean... didnt everything that is around today evolve from species that weren't wiped out?
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.
No pressure.
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!
This seems off... by counterexample, my grandfather had no sons, but three daughters (one being my mother).
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!
This discovery channel video might help put things in perspective:
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.
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.
Legless lizards and snakes some to convergent evolution. But its of course possible that other legless lizards existed before that.
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’s no way to make sure everyone believes anything. So. No.
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.
The entire field of palentology seems like an acrimonous mess.
https://www.theatlantic.com/magazine/archive/2018/09/dinosau...
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.
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.
http://www.geologyinmotion.com/2011/10/chicxulub-impact-what...
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.
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.
I…really thought this was going to be a joke post based on this sentence!
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.
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.
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.
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.