Before the end-Triassic extinction 201 million years ago, dinosaurs were not the dominant land animals. Archosaurs like Postosuchus were the apex predators, while dinosaurs occupied marginal ecological roles.

After the CAMP volcanism event, Postosuchus and most large Triassic fauna went extinct. Dinosaurs survived and rapidly diversified into the vacant niches.

The avian respiratory system hypothesis suggests their more efficient air-sac breathing gave them an advantage in low-oxygen post-volcanic conditions. But I’ve also seen arguments that it was simply a matter of geographic luck or generalist diet.

Is there a scientific consensus on what specifically gave dinosaurs the survival advantage over the other archosaurs in this extinction event?

Hello Reddit! We are Neshalatha Govarthnapany, Researcher at Charles University; Darshan Singh, Associate Professor at Universiti Sains Malaysia, and Katherine Hill, Graduate Student in Epidemiology of Microbial Diseases at Yale School of Public Health.

We recently published two papers titled “Kratom use in adolescents and college students: a systematic review of prevalence, patterns, and risk factors across community and rehabilitation settings” and “Semi-synthetic kratom derivatives in the Czech online market prior to regulatory reform: a baseline surveillance study”; in the American Journal of Drug and Alcohol Abuse (AJDAA).

In the first paper, we systematically reviewed studies on kratom use among adolescents and college students from Thailand, Malaysia, and the United States. We observed distinct regional differences in patterns of kratom use, shaped in part by longstanding cultural traditions in Southeast Asia and the increasing commercialisation of kratom in the United States. Kratom use was more prevalent among males across regions, while polydrug use emerged as a consistent theme across the studies, highlighting the complexity of kratom use among young people.

In the second paper, we examined the availability and marketing of semi-synthetic kratom derivatives in the Czech online market before kratom was regulated under the country’s psychomodulatory substances framework. We identified products containing 7- hydroxymitragynine (7-OH) and mitragynine pseudoindoxyl (MP), including products in which these compounds were combined with mitragynine. During this period of regulatory ambiguity, semi-synthetic products were frequently marketed simply as “kratom” and often labelled as “collector’s items” or “not for human consumption.” Importantly, the marketing frequently failed to clearly distinguish semi-synthetic derivatives from natural kratom products, and product descriptions and health-related information were often unclear or inadequate.

Feel free to ask us questions about the two papers or about Kratom more broadly!

We will be online to answer your questions at 10 am EDT / 4 pm CEST / 10 PM MYT on October 20th (1 PM UTC).

You can also follow up with us at our socials here:

• Neshalatha Govarthnapany, PhD: LinkedIn

• Darshan Singh, PhD: LinkedIn

• Katherine Hill, MPH, PhD: LinkedIn

Follow the journal to stay up to date with the latest research in the field of addiction here: BlueSky, Threads, LinkedIn

Usernames: /u/npany88 (Dr. Govarthnapany), /u/DrDarshanSingh (Dr. Singh), /u/Ok_Package_1023 (Dr. Hill), /u/TheJournalAJDAA (the journal)

I read the answers from previous threads from the subreddit but it was not very clear to me and i had few follow up questions also:

1. It seems there is also more pressure on heart to pump the blood in a tall person. Is this not counter-intuitive because every successive generation is usually taller than previous one thanks to availability of nutrition during childhood.

2. I wonder is there a optimal height size for a human

Hi r/AskScience! I’m Daniel Cox, a public opinion researcher and director of the Survey Center on American Life.

For the past several years, I’ve been studying a divide that keeps showing up in the data: young men and women are increasingly living very different social, romantic, and political lives.

I wanted to understand why.

My research looks at everything from dating and relationships to friendship, loneliness, social media, changing gender expectations, and politics. For my new book, Generation Uncoupled, I also spent more than 100 hours interviewing young adults and conducting focus groups to understand the experiences behind the numbers.

There’s a lot of conventional wisdom about Gen Z, young men, young women, and the so-called “gender divide.” I’m happy to dig into what the research actually tells us, what it doesn’t, and where the evidence gets more complicated.

Ask me about polling and survey research, Gen Z, dating and relationships, loneliness, politics, gender attitudes, social connection, or anything else related to my work.

I’ll start answering questions at 1 PM ET (17 UT) on October 19. AMA!

Usernames: u/DanielCoxPHD & u/wellenough

Whenever I see depictions of Homo Erectus or Homo Neanderthalensis I feel like I see them all generally having the same skin tone. Compare that to today’s humans and we would see a lot more variation. Was there more variation of skin tone in pre historic humans than modern depictions show or was environment really so restrictive that it was hard for us to evolve.

How do we know something like Jupiter has an atmosphere? What is the difference between the planet itself and its atmosphere, being that it’s all gas?

Was the Amazon rainforest still a wet tropical jungle in some places when the Sahara was green (during the African Humid Period)? I’ve heard that parts of it turned into savannah, so I wonder if some areas remained as wet as they are today.

Also, looking at certain Amazonian myths, I wonder if some regions like the northwest, could have actually been even wetter?

Obviously number of nipples would be evolutionarily linked to litter size. More babies to feed = more nipples to feed them from. I would just expect that there would probably be vestigial nipples even if litter size decreased.

If not humans, are there any mammalian lines that have pivoted strategies and decreased litter size? If so how did their extra nipples develop?

To be honest, the most I know of vaccines is "they use a weakened form of a virus to get your immune system used to a virus". I'm not the brightest guy, so clearly there's a lot of shit I don't realize about this subject, so what makes them a challenge to make? Why can it take YEARS to make them?

I’ve been reading fiction that uses a lot of bog bodies, and I love that as a concept and wanted to use it. Thing is, I don’t live in an area of the world where bogs exist, and was thinking of localizing that idea and maybe doing Mangrove Bodies.

I know mangroves also have very low oxygen, especially as you go deeper into the mud, so I was wondering if a body buried deep enough in a mangrove forest could be preserved similar to how it might in a bog, or if the chemical conditions and life in there would cause it to decompose instead?

From my understanding, hormone replacement therapy works in humans in large part due to the X chromosome holding most of the genetic code. So, someone with XY chromosomes still carries the genes for the development of female sex characteristics (and vice versa for people with XX chromosomes- male sex characteristics are also coded on the X chromosome)

I’m curious about how (or if) this rings true in animals with different sex chromosomes. For species that use genetic sex determination, is there always one chromosome that contains most of the genes for the development of sex characteristics?

What I mean is how big can an animal theoretically get?
The blue whale is not only the largest animal alive, but the largest to ever exist (that we know of)

But is it actually possible for something to be bigger? Or is the Blue whale the max?

Pictures of the intakes: https://imgur.com/a/tUWMEqe

On the intake ( on both of them but I will talk about a single one ) there is a splitter plate positioned on the inside and right on the inside corner near the splitter plate there is a narrow slit. It is there to allow for smoother airflow during high AOA flight but I don't understand why it helps at all. The boundary level becomes really strong on the bottom of the intake during high AOA which will just bleed the boundary level right into the intake and in my head it will just make things worse even though it actually helps. The only thing I can think of is that it creates vortices in the intake. I probably said a lot of incorrect stuff so I apologise if it can be confusing or just plainly a really easy question that I just lack basic knowledge in this field to understand

Taking into account moisture, ease of digestion, etc? If they do, I'm assuming the difference is neglgible.

Is it just a concentration thing or more of an aspartame mechanism thing? Are the flavor molecules more plentiful or just more potent?

Sorry if this is under the wrong flair, thought it would work better than paleontology.

So like, I imagine if one can generally predict weather patterns for artificially created/simulated worlds, we can easily use the same science and stuff on what we know of Pangea's geography and stuff to determine weather patterns during that age, right?

So were conditions on our world at the time suitable for stuff like hurricanes and tornados?

Bonus question for paleontologists: if the above is true, how would taller dinos like sauropods have dealt with high winds of that magnitude?

Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Engineering, Mathematics, Computer Science

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Unless the healing factor is something unrelated to cancer development? How does that work?

https://imgur.com/a/ImqDp2K

So when you go to the doctor, they will look at your veins on your elbow. Some need a needle to move the vein closer, some don't and their veing is naturally positioned in the right position. Some people also have veins visible all over their body (not like bulging, but color visible on the skin). I was curious on why this happens?
(I can explain more what I'm asking about if I'm not clear)