Answer: What's that in the belly of the Redondasaurus?

 It's not everyday you see a phytosaur... 

... yet, there it was in the Carnegie Museum of Natural History. Big, with an impressive set of teeth, and looking for all the world like a massive crocodile. 

This is Redondasaurus bermani. 

But what really shocked me was what looks just like ribs in its belly.  Is that a thing?  Why have I never noticed this before?    

Here's a close-up shot: 

See what I mean?  There is the backbone above, with a lot of ribs hanging off the vertebrae.  You can easily see the massive leg bones and feet. 

Here's a redrawing I made of the photo, emphasizing the "belly ribs." 

Note how they seem to be kind of U-shaped, with long, pointed arms wrapping up as if to encase the abdomen.  Note too how the ribs hanging down from above are squared-off at the ends.  The two different kinds of ribs look very, very different.  These belly ribs are mostly free-floating except for the one at the left, which attaches to a kind of sternum that runs up to the phytosaur equivalent of a collar bone.  

I don't know that I've seen that on any other animal.  Or have I just not been paying attention?  

Here are last week's two Challenges for you: 

1. What do you call that thing in the chest and belly of the Redondasaurus bermani?  

For something that I'd never seen before, I was pleased with my first query: 

     [ ribs in dinosaur belly ] 

Yes, I know that technically the Redondasaurus isn't a dinosaur (it's a phytosaur), but for the purposes of searching, I figured that the term "dinosaur" would be used on the page, if only to explain that it's not a dinosaur.

This query worked remarkably well, and told me about a word I'd never read before: gastralia, the "belly bones" of dinosaurs, such as the T. rex.  

Naturally I checked.  Just because a therapod like T. rex (that lived during the Cretaceous period, about 70 to 65 million years ago), there's no guarantee that a phytosaur (that lived during the Triassic some 252-201 million years ago) would have the same skeletal feature. There's a decent change that something might have evolved differently over the distance of 180 million years. 

A quick search for: 

     [ gastralia phytosaur ] 

leads to all kinds of interesting results, including this book chapter (from Vertebrate Evolution) with lovely illustrations of Redondasaurus and its gastralia. 

Bottom line: these additional bones are called gastralia, and were (as Regular Reader remmij pointed out), pretty clearly used as part of their breathing apparatus.

 Remmij used the search [Dinosaur gastralia and their function in respiration] and found Some video that might be helpful for understanding gastralia's role in breathing.

2. Do other animals have this thing now, or was it just an Age of the Dinosaurs skeletal feature?  

What about modern animals with gastralia?

The Wikipedia article about gastralia tells us that "Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods." That's a complicated way of saying that there's a basket of bones in the belly of the beasts... or at least of some crocodilians (alligators and crocodiles) and tuatara (a kind of lizard from New Zealand).  

But to remember the past, as we've seen already, gastralia are also part of other classic dinosaurs such as T-rex.  

As you know, there's a T-rex skeleton on the Googleplex campus in Mountain View, California.  (Discussed before in SRS.)  Here's Stan, the Google T-rex with flamingos... 

But note that Stan seems to be missing his gastralia!  Here's a better image to show the missing bones. I see ribs, but no gastralia.   

When I did an image search for [ t-rex skeletons ] I found this somewhat variable set of results: 

As you can see, about half of the reconstructed skeletons (including the one of Stan from the Black Hills) are missing their gastralia.  

A quick search for [ missing gastralia ] led me to this article from the Field Museum (Chicago) about how they recently revamped their T-rex display of Sue.  (It's worth clicking on that link--it's a really nice article about how they changed their minds about Sue's abdominal bones.) 

When fossil hunters first uncovered SUE, they found a set of rib-like bones that clearly belonged to the dinosaur, but no one was really sure where they fit in with the rest of the skeleton.

Now we know that the gastralia sit below the ribs and along the belly. Most likely, they helped T. rex breathe by pushing air in and out of the lungs (we humans have a diaphragm for this purpose). SUE’s gastral basket is the most complete among over 30 known T. rex specimens. It includes 26 of approximately 60 total gastral bones. We don't know exactly how many bones make up the gastralia since most—but not all—segments consist of two pieces. And there isn't yet a complete T. rex gastralia for us to check out and confirm how many segments do have two pieces.

So our understanding the appearance of a T-rex has changed over time. Now, if you see a T-rex without a gastralia, you know that someone has left out part of the skeleton! 

SearchResearch Lessons

This wasn't a difficult search--my very first search was pretty obvious [ribs in dinosaur belly], but it worked just fine, and I learned a very specific term--gastralia--that was useful in digging more deeply into the subject. 

It was great fun to learn that so many dinosaurs skeletons that we see in museums (and on the silver screen) are actually missing a major part of their anatomy.  But by doing quick visual comparisons, we came to learn how to see dino skeletons as part of a full ensemble.  

As a reminder of the value of checking Wikipedia articles in other languages, Regular Reader Ramón points out that in the Spanish language Wikipedia article on gastralia it tells us about the origin of the term: 

"Dinosaur gastralia were first described by Eudes-Deslongchamps in 1838 in Poekilopleuron bucklandii , but without having recognized them as dermal bones. Therefore, Osborn's description of the gastralia of a Tyrannosaurus rex from 1906 is often cited as the first description."

Even though T-rex gastralia were among the first described (over 100 years ago), they're STILL left off of many T-rex skeletons.  

Keep searching! 

SearchResearch Challenge (8/23/23): What's that in the belly of the Redondasaurus?

 I looked at the Phytosaur in real shock... 

Because there, in the dinosaur hall of the Carnegie Museum of Natural History in central Pittsburgh, was what looked to be a massive crocodile.  

This is Redondasaurus bermani. It was huge and utterly evil looking, clearly a watery death machine that was 6.4 m (21 feet) long, and lived in the rivers and swamps of Triassic North America some 252-201 million years ago.

Impressive.  

I've seen lots of assembled skeletons before.  It was big and carnivorous, but as I stood in front of the skeleton, I noticed something that I don't think I'd seen before.  

See that collection of what look like ribs in its belly?  

Here's a close-up shot: 

See what I mean?  There is the backbone above, with a lot of ribs hanging off the vertebrae.  You can easily see the massive leg bones and feet. 

But there, hanging below the backbone and ribs is something else--a kind of basket of upward pointing ribs that seems attached to the sternum.  

I don't know that I've seen that on any other animal.  Or have I just not been paying attention?  

Naturally, this led me on a merry SRS quest, which condensed into these two Challenges for you: 

1. What do you call that thing in the chest and belly of the Redondosaurus bermani?  

2. Do other animals have this thing now, or was it just an Age of the Dinosaurs skeletal feature?  

I've found the answer now after a bit of quick searching on my phone while standing in front of the beast.  I have to say, I was pretty surprised by the answer to Challenge 2.  

Another surprise was learning that the Redondosaurus is actually NOT related to any living crocodiles or alligators?  It was, as they say, a "Late Triassic clade of crocodylian-like predators."  That is, there were other kinds of Redondosaurus (collectively called the Phytosaurs) that filled the ecological niche that crocs and alligators fill in todays swamps.  They had short legs, wide, heavy bodies with rows of armored scales, long tails, and long toothy snouts. The only obvious difference between crocodiles and phytosaurs is that crocodiles have their nostrils at the ends of their snouts, and phytosaurs had them on raised hump in front of their eyes. Despite the strong similarities between phytosaurs and crocodiles, the two groups are not closely related.

Let us know what answers you found to this week's Challenge.  Of course, tell us HOW you found them.  We all want to learn from your search strategy.  

Hope you find this as interesting and entertaining as I did.  

Keep searching! 

Answer: Animal? Plant? How do you know?

Mixotrophs for the win...  

Elysia chlorotica, a sea slug that incorporates chloroplasts into its body.
P/C Patrick J. Krug, Creative Commons CC BY-NC 3.0 license, via Wikimedia Commons

Remember the Elysia cholorotica (the big green slug above, aka "Emerald green sea slug")?   

It's technically a mixotroph, but it's pretty big (up to 60 mm in length, but typically between 20 mm to 30 mm).  As you know, they feed on algae, extracting chloroplasts and then merging them into its body, making it able to both eat food AND use sunlight to photosynthesize for energy.  

We also know about other slugs (also called nudibranchs) that will steal the nematocysts of cnidarians (such as sea anemones, hydroids, jellyfish, corals, siphonophores, etc.). The slugs use them for defense, with the nematocysts stinging anything that tries to eat the nudibranch.  The nematocysts are stored in protruding cerata (those spine-looking things) on their backs.  And at the tip of each branch of the cerata, the nematocysts are stored in a small sac, the cnidosac. 

Here's a spectacular photo of an aeolid nudibranch taken by SRS friend Randall Spangler.  

The cerata on the back of this Aeolidia papillosa end with cnidosacs.  Like Elysia, they incorporate dinoflagellates that provides some photosynthesis capability.  P/C Randall Spangler. 

But the term mixotroph usually refers to really small critters--plankton--that are microscopic--much smaller than slugs. The size table from the Wikipedia article about plankton gives this as the breakdown for different kinds of small plankton.  

We're primarily interested in the smallish single-celled plankton--and only those that are carnivorous... if that means anything at the single-cell level.  

This led to a couple of questions about the microscopic mixotrophic plankton. To wit,   

1. Do mixotrophic plankton ONLY steal chloroplasts, or are their other kinds of organelles that they rip out of the prey?  If so, what else gets stolen? 

Started my search with a "fill in the blank" style search: 

      [ mixotrophs “steal the *”] 

And find this article on mixotrophs in Science Daily. 

“Traditionally mixotrophs are considered as curiosities or irrelevant. ... for the first time, [they have] mapped the presence of these "body-snatching" mixotrophs which shows that they are present in oceans all over the world.

These "body-snatchers" come in two forms. One type steal the photosynthetic factories from their prey during digestion and use these chloroplasts to make food as do plants. Other mixotrophs enslave whole photosynthetic prey communities within their body, drifting in the oceans like microscopic green houses. Marine researchers have been mislabelling 50% of these organisms as "animals" when they are actually eating and photosynthesizing within the one cell. The good body-snatchers support fisheries, while the bad ones can be highly toxic.” 

Fascinating.  Clearly, some mixotrophs steal the chloroplasts and incorporate them into their own bodies.  That's not too much of a surprise.  Unlike the Elysia, it's happening at the microscopic level, but it's the same idea.  Steal a chlorplast and live a microscopic life of luxury.  

In addition, some single cell mixotrophs ingest the whole prey organism and keep them intact, but within their body.  Plankton using this "swallow them whole" strategy are called endosymbiotic specialist nonconstitutive mixotrophs.  (You can use that phrase at your next party as you devour your very tasty living oyster.) 

Example: Noctiluca scintillans eats Pedinomonas notilucae, harboring them like a little garden of plants to generate important nutrients. 

But in my reading, I seem to remember some mixotrophs that ingested more than just the chloroplasts. 

On a lark, I turned to both Bard and ChatGPT for their opinions, asking both 

     [ do some mixotrophs steal organelles
       other than chloroplasts? ] 

Bing's version of ChatGPT told me that: 

"Yes, some mixotrophs can steal organelles other than chloroplasts. According to a Wikipedia article on mixotrophs, there are two types of eukaryotic mixotrophs: those with their own chloroplasts, and those with endosymbionts—and those that acquire them through kleptoplasty or through symbiotic associations with prey or enslavement of their organelles." 

That's fine, but it's basically what we already knew.  

Bard told me that: 

"Yes, some mixotrophs steal organelles other than chloroplasts. For example, the green hydra (Hydra viridissima) is a freshwater polyp that can steal chloroplasts from the algae it consumes. The chloroplasts are incorporated into the hydra's cells and allow it to photosynthesize. The hydra can also steal other organelles from algae, such as mitochondria and nuclei.

Another example of a mixotroph that steals organelles is the coral Pocillopora damicornis. This coral can steal chloroplasts from the algae that live in its tissues. The chloroplasts provide the coral with energy, which it uses to grow and reproduce.

The ability to steal organelles is a rare adaptation, but it is found in a variety of organisms. This ability allows these organisms to get the best of both worlds: they can photosynthesize and produce their own food, but they can also consume other organisms for nutrients.

Here are some other examples of mixotrophs that steal organelles:

The dinoflagellate Gonyaulax tamarensis can steal mitochondria from other dinoflagellates.

The ciliate Paramecium bursaria can steal chloroplasts from the green algae Euglena gracilis.

The fungus Pythium insidiosum can steal mitochondria from the plant cells it infects."

Again, we knew most of this.  But Bard also told me that some mixotrophs also steal mitochondria.  And that's a different organelle than the chloroplasts.  Interesting.  Are there others beyond mitochondria?  

So I changed my prompt to be: 

     [ do mixotrophic plankton only steal chloroplasts or are there other organelles that get ripped out of their prey?  If so, what else gets stolen? ] 

Bing/ChatGPT told me that: 

According to an article in Scientific American, Mesodinium is a mixotroph that sucks photosynthesizing organs from another organism called Dinophysis. Mesodinium takes in the organelles responsible for photosynthesis whole. Within minutes the pale Mesodinium starts to turn darker red as it fills its body with the stolen parts—chloroplasts and nucleosomes—which remain intact and functional. Mesodinium is not able to take in and use carbon dioxide as true photosynthesizers are, so it relies on its victims’ chloroplasts to accomplish that task

Bing also gave me a link to the Scientific American article with the information.  Nice job. 

The same prompt to Bard told me basically the same information, but without the details and certainly with the link to a useful article.  It did, however, mention that some mixotrophs also steal vacuoles.  

That doesn't make a lot of sense, so I checked it by reading a few papers on mixotrophs with vacuoles, and found that the mixotrophs often ingest their prey into THEIR vacuoles, not that they ingest the vacuole from the prey.  That's an important distinction that Bard got just slightly wrong. The vacuoles are where the stolen organisms are kept in the klepto-organism!    

Curious about the role of nucleosome theft in Mesodinium, I did a search for: 

     [ mesodinium mixotrophy nucleosomes ] 

and found a number of articles about how Mesodinium DOES in fact steal nucleosomes.  But why?  

In their Nature (2007) paper "Retention of transcriptionally active cryptophyte nuclei", Johnson, et al. show that the nucleosomes are "transcriptionally active,"  (that is, they're busy working within the body of the mixotroph) making substances that the chloroplasts that were also stolen just happen to need.  

Isn't that handy?  The mixotroph steals the chloroplasts AND the nucleosomes that also contain the instructions for the care and feeding of the chloroplasts.  

Alas, the nuclei only seem to last for about a month in the body of mixotroph, so they need keep eating in order to keep things running.  

So we've figured out that mixotrophs not only steal chloroplasts, but also mitochondria and nucleosomes.  

The dual presence of mitochondria and functional chloroplasts within these mixotrophic cells that have been stolen from another species of plankton suggests a high degree of biochemical similarity.  I didn't expect that degree of interoperability.  This is likely the key to their functional presence and essential endosymbiotic activity for over 2.5 billion years.

Totally amazing.  

2. How long has the concept of mixotrophic plankton been around?  Is it possible that this is relatively new understanding of planktonic ecology?  

The obvious approach here is to check out Google Ngrams for a brief history of the use of the terms that start with "mixotroph-."  

Here's that chart: 

It looks like the first uses of "mixotrophic" starts in 1900, but then really picks up in the 1970-2000, falls a bit, then really takes off around 2010.  

Of course, this is only from the Books corpus, so to get a better sense of the use of the word in the scientific literature, I turn to Scholar.Google.com and filter by date, here I'm filtering for papers published up to 1940. 

Note that there are about 34 results pre-1940.  

But ALSO note that several of those (results 3, 4, 5) are all actually from the 2000s.  (I checked: they actually are from the 2000s and are not pre-1940. Metadata problems.)  

Luckily, those date errors don't change the overall story.  Mixotroph-* came into common usage around 1950, with the other forms of the word (mixotrophy, mixotrophic) really becoming common after 1990.  Since I had completed my graduate training by 1984, it's very likely I never heard the word before running across it in that Scientific American article.  In the grand sweep of scientific history, it's a relatively recent word.  

SearchResearch Lessons 

1. Remember the fill-in-the-blank search method.  (That is, the * search.)  It can come in handy when you're looking for possible completions.  

2. LLMs can be handy tools for finding concepts and terms to further your own searching.  In all of the LLM examples here, there were problems with the text they generated.  HOWEVER, they also gave me some great ideas about what to search for next.  Be sure to check out their claims--don't just accept what an LLM tells you at face value.  (Example: Bard was deeply confused about the role of vacuoles in mixotrophy.)  

3. Bing shows citations for claims made--that's a really nice feature.  I sure wish that Bard would do the same.  (Oddly enough, for a few short weeks, Bard included citations.  It has since stopped doing that.  Don't know why, but I can guess that it was hallucinating too many references. Pity.)  

P.S.  A couple of people pointed out that they're not biologists and found reading the papers about this fairly esoteric topic to be heavy going.  One nice feature of the LLMs is that they are pretty decent at summarization.  Here's one such summary of an abstract from the  Johnson paper of above.  Here's the prompt, and Bard's nice summary... 

Dan:  I need a simplified summary of this article.  Can you give this to me at a 9th grade level? It is well documented that organelles can be retained and used by predatory organisms, but in most cases such sequestrations are limited to plastids of algal prey. Furthermore, sequestrations of prey organelles are typically highly ephemeral as a result of the inability of the organelle to remain functional in the absence of numerous nuclear-encoded genes involved in its regulation, division and function. The marine photosynthetic ciliate Myrionecta rubra (Lohmann 1908) Jankowski 1976 (the same as Mesodinium rubrum) is known to possess organelles of cryptophyte origin, which has led to debate concerning their status as permanent symbiotic or temporary sequestered fixtures. Recently, M. rubra has been shown to steal plastids (that is, chloroplasts) from the cryptomonad, Geminigera cryophila, and prey nuclei were observed to accumulate after feeding. Here we show that cryptophyte nuclei in M. rubra are retained for up to 30 days, are transcriptionally active and service plastids derived from multiple cryptophyte cells. Expression of a cryptophyte nuclear-encoded gene involved in plastid function declined in M. rubra as the sequestered nuclei disappeared from the population. Cytokinesis, plastid performance and their replication are dependent on recurrent stealing of cryptophyte nuclei. Karyoklepty (from Greek karydi, kernel; kleftis, thief) represents a previously unknown evolutionary strategy for acquiring biochemical potential.

Bard: 

Sure, here is a simplified summary of the article at a 9th grade level:

* Some organisms can steal organelles from other organisms and use them for their own benefit. This is called organelle sequestration.

* In most cases, organelle sequestration is short-lived because the organelles can't function without the genes from the organism that they were stolen from.

* The marine organism Myrionecta rubra can steal plastids (chloroplasts) from the cryptomonad Geminigera cryophila.

* M. rubra can keep the cryptophyte nuclei for up to 30 days. These nuclei are still active and help to keep the plastids functioning.

* Without the cryptophyte nuclei, the plastids in M. rubra stop working. This means that M. rubra needs to keep stealing nuclei from cryptomonads in order to stay alive.

* This is a new way for organisms to get the nutrients they need. It's called karyoklepty, which means "nucleus theft."

I hope this summary is helpful! Let me know if you have any other questions.

That was nice, Bard.  

For you humans... Keep searching! 

SearchResearch Challenge (8/9/23): Animal? Plant? How do you know?

 I love learning something that radically changes my understanding of the world... 

Elysia chlorotica, a sea slug that incorporates chloroplasts into its body.
P/C Patrick J. Krug, Creative Commons CC BY-NC 3.0 license, via Wikimedia Commons

If you're a regular SRS reader you might remember our discussion a while back about how some animals incorporate other animal parts into their body.  (SRS "Internal Incorporation" May 5, 2021)  

In that post I showed one of the best examples of this, Elysia cholorotica (the big green slug above, aka "Emerald green sea slug") which feeds on algae, and in the process, extracts their chloroplasts (NOT digesting them) and then merging them into its body, making it able to both eat food AND use sunlight to photosynthesize for energy.  

That's very cool. 

And we know about plants that eat insects (Venus flytrap, sundew, pitcher plants, etc.), so the idea of plants eating animals for nutrients, and the inverse of that--animals eating plants to steal body parts--isn't a huge surprise. 

However...  I always thought that plants were plants (mostly photosynthesizing) and animals were active eaters of other organisms. That's sort of the classical breakdown--plants sit still in the sunlight, animals move.  Sure, some animals (e.g., corals, mussels) sit still and let currents bring food to them, but mostly that's the split.  Plants are still, immobile, fixed to a location.  Animals move around and get their food.  

I also had learned that most plankton in the ocean were either phytoplankton, which are plants, and zooplankton, which are animals. The natural order of things was that zooplankton eat the phytoplankton.  

Like other plants, phytoplankton take in CO2 and release oxygen. As a result, phytoplankton account for about half of ALL photosynthesis on Earth, making them one of the world’s most important producers of oxygen. 

But then I read something that deeply surprised me:  In a Scientific American article ("The Perfect Beast," April 2018) I learned about mixotrophs, single-celled plankton that are neither really animals nor plants, but a weird mix of the two.  They're just one cell, but they can attack and feed on other unicellular plankton, including those that have chloroplasts, which they then use just like Elysia chlorotica.  

That's a bit of a surprise--that body part incorporation happens at the single-cell level, with some single-cell plankton stealing chloroplasts from other single-cell green algae. 

But then the article went on to say that around 50% of ALL single cell organisms in the sea are mixotrophic--that is, half of all the unicellular plankton can attack and eat others, making the ocean a scene of constant, unrelenting warfare.  

The big surprise to me was that I'd never heard of the word "mixotrophic" before.  It's such an unusual word that I'm pretty sure I would have remembered it.  So, how did I miss it? 

That's the part I love about my reading--I'm constantly learning new things, including deep ideas that overturn my long-held beliefs.  There's that moment of frisson when you realize that what you know needs to be updated--to change in a way that you never thought possible.  

Like many of you, I used to think that unicellular plankton were either plants or animals with a clear division between them and that the majority of unicellular plankton were quietly hanging out in the water column, photosynthesizing and making oxygen for the world.  

Ah, now... apparently the unicellular world is red in tooth and flagella, with one-celled organisms finding, attacking, and consuming others, and stealing body parts. 

These are plants that actively hunt down other mobile plankton.  "Plants that hunt,"  or are they "animals that photosynthesize."  Either way, the neat divisions break down, which is kind of reflective of our times.  The more you know, the less clear the categories really are.  

As I read the article, several research Challenges came immediately to mind.  Can you help me answer these?  

1. Do mixotrophic plankton ONLY steal chloroplasts, or are their other kinds of organelles that they rip out of the prey?  If so, what else gets stolen? 

2. How long has the concept of mixotrophic plankton been around?  Is it possible that this is relatively new understanding of planktonic ecology?  

Of course, I'd love to know the answers to these Challenges, but just as important, be sure to let us know HOW you figured out those answers.  What SRS methods did you use?  We all want to learn how to do this kind of deep research. 

Keep searching! 

Answer: How do you know what to still believe?

What we believe to be true...   

Dall-E. [ digital art young man looking at a skull on the desktop ]

... changes over time. 

That's good because it generally means that we, as a culture, are figuring things out.  It's easy to come up with a list of things that we no longer believe to be true.  

But the bigger Challenge for today is this:  How can we SearchResearchers come to understand how an idea is changing over time?  If we learned something a while ago (say, when you were half the age you are now), should you still believe that this is true?  

In the Challenge last week I gave two examples of psychology discoveries that might (or might not) be thought of as true.   

A.  In 1977, a famous paper by Richard Nisbett and Timothy Wilson ("Telling more than we can know") argued that people cannot introspect about cognitive processes.  

Is that true?  Or, more in keeping with this week's Challenge--does the field of psychology still believe this to be true? 

B.  In 1996, another famous social psychology result is that if you primed people with ideas and words about growing old (such as feeble, worried, Florida, elderly, forgetful) then they will walk more slowly after exposure to such materials.  See: "Automaticity of Social Behavior: Direct Effects of Trait Construct and Stereotype Activation on Action" by  John A. Bargh, Mark Chen, and Lara Burrows (1996).

Is that true?  Or, more in keeping with this week's Challenge--does the field of psychology still believe this to be true?  

With all that as background, let me pose the Challenge with this caveat: Our Challenge is not whether or not both of these results are true or not, but really what techniques should you know to be able to determine if something is still widely believed or not?  

1. Can you find out how well has these two results have withstood the test of time?  Is it still considered to be true?  Is it something we should be teaching in our psychology courses today?  What SearchResearch process would you use to figure this out?  

First off, here I'm going to talk about ideas in the sciences, and not about political or informal knowledge.  (That's a whole other ballgame, though some of the ideas here will carry over to that kind of investigation.)  

A big issue for much of humanity is that some kinds of knowledge get hardwired into the culture and is difficult to displace with more up-to-date knowledge.  (That's kind of the point of Kuhn's Structure of Scientific Revolutions, new knowledge doesn't just diffuse gently into a culture, but has to go through a kind of revolutionary phase where it's not widely believed, but then a major shift happens.)  

For instance, when I was young, a common treatment for burns in the home was to smear butter all over it.  That was part of "common knowledge," and widely accepted.  (It is NOT the best way to treat a household burn.)  

In the case of social psychology results from above, they both seem to defy "common knowledge."  Nisbett and Wilson's paper tells us that people seem unable to talk about what they're actually thinking--does that sound right to you?  While Bargh's paper tells us that simply priming people with "old words" actually changes their behavior (especially visible in their walking speed).  

To verify the current thinking about these two papers, I'd start by doing a few searches for articles about the original papers and claims: 

A. Search for the claims made in the original papers.   In particular, make sure you’ve got the right search terms (what’s in the popular press may not be what's written about in scholarly articles). Use author names and the terms that they use.  For instance, Nisbett uses phrases like "introspection" and "cognitive processes."  Bargh uses terms like "automaticity" and "stereotype activation."  Start your searches with authors + key phrases that are not likely to have other meanings.  

And, of course, when you find a hit, read it carefully.  Does the newer article support the findings or contradict them?  Does it give new insights or shift in interpretation?  

B. Search for follow-up articles with the "in" search pattern.  In particular, look for ones that use the title of the original paper (or finding) in THEIR title.  For instance, I found this article, What's next for psychology's embattled field of social priming,  by searching for [Bargh "social priming"].  Another method is to find articles by searching for an explicit mention of the first paper  (For example, a search like this, where I'm searching for the lead-in word "in"  [“in Telling more than we can know”] leads to many articles about that original paper.)  

C. Try an LLM – you might get some clues.  My prompt to Bard (which gave a reasonable answer) was: 

[ In Telling More Than We Can Know, Nisbett and Wilson (1977) demonstrated the limits of one's ability to introspect about the nature of cognitive processing. But work has been done since then.  How well has this idea lasted over the past 40 years.  Is this result widely believed now?] 

Bard response: The idea that people are not very good at introspecting about their own cognitive processes has held up well over the past 40 years. There have been many studies since Nisbett and Wilson's (1977) seminal paper that have replicated their findings and extended them to other areas of cognition. For example, one study found that people are not very good at explaining why they made a particular decision, even when they are given all the information that was available to them at the time of the decision (Wilson, Dunn, Kraft, & Lisle, 1989).

This result is widely believed now among cognitive psychologists. It is one of the reasons why so much research in this area is focused on using indirect methods to study cognition, such as reaction time tasks and eye tracking. These methods allow researchers to measure people's cognitive processes without relying on their introspections.

However, it is important to note that the idea that people are not very good at introspecting about their own cognitive processes is not absolute. There are some cases where people are able to provide accurate reports of their thoughts and feelings. For example, people are generally good at reporting the content of their memories (Schacter, 1996).

Overall, the idea that people are not very good at introspecting about their own cognitive processes is a well-supported one. It has been replicated in many studies and is widely believed among cognitive psychologists. However, it is important to note that this is not an absolute rule, and there are some cases where people are able to provide accurate reports of their thoughts and feelings.

It didn't tell me much that I didn't know, but Bard's response DID point me to two additional papers (Wilson et al., 1989; and Schacter, 1996). Unfortunately, the Schacter paper is all about illusory memories, that is, how people THINK they're accurately reporting their memories, but actually are not.  (In other words, Bard has it totally backwards.)  

But despite getting the claim about people being "generally good at reporting the content of their memories," I read Schacter's paper about how people totally do NOT understand the accuracy of their memories... which is exactly what Nisbett was saying.  

My point, though, is that the LLMs can still give you interesting pointers into the literature, even if they don't get the meaning right!  

D. Use Scholar’s “cited-by” feature to see subsequent articles that refer to the original. If I look at the Scholar entry for  “Nisbett and Wilson Revisited” article, I see this: 

Naturally, if you look at the other papers that cite this one, at least a few of them will provide color commentary on how the ideas have withstood the test of time.  

E. Check books as a historical record.  To use Google Books this way, just search for the authors or the key ideas of the papers and see where that takes you.   Here's a search for Nisbett and Wilson.  Here you can see some of the collected opinions of how that original research result from 1977 plays out in current texts.  (Including a book by T. D. Wilson from 2004).  

F. Search for overviews of the field (or authors).  Just searching for [overview <key terms>] often gets you what you need.  Here's that search in Scholar: 

You can get a hint from this that the field of priming research is having a bit of a struggle these days.  It's clear that replicating those studies from the 1990s is turning out to be more difficult than people suspected.  The results were clearly remarkable and changed the field of social psychology, but with subsequent work, it's turning out to be hard to reproduce the effects originally supported.  Upshot: there probably is a real effect of priming, but the behaviors primed are perhaps not as strong and surprising as we once thought.  

As I said, my goal wasn't to teach you about these results in particular, but about how to do follow-ups on work that has been previously published.  In summary: 

SearchResearch Lessons 

A. Search for claims made in the original papers.  Be sure to keep the authors and key concepts in the search.  

B. Search for follow-ups using the "in+title" pattern.  Works more often than you'd expect.  

C. Try an LLM to ask your question.  But as always, verify whatever it tells you.  It might get something totally wrong... 

D. Use Google Scholar's "cited-by" feature. It's a pretty amazing capability to look at other articles that have used those paper in their arguments.  It might be worth checking out a few of those citing papers to see what they say about the original.  

E.  Remember to check books on the topic. It's amazing to me how often I can find a book with commentary on ideas from the past.  

F. Search for overviews of the topic.  Using the simple search pattern [overview + <key terms>] will often get you an article that overviews / summarizes the entire topic.  

Hope you find these search tips useful.  Try them on your next topic!  

Keep searching!