Why a Pterosaur Is Not a Dinosaur | Hacker News Reader

Why a Pterosaur Is Not a Dinosaur

smithsonianmag.com

68 pointsnonbel75 comments

“Dinosaur” is a word for a specific group of creatures united by shared characteristics and which had their own evolutionary history—it is not a catch-all term for anything reptilian and prehistoric"

Fascinating, didn't know Pterosauria split off from Dinosauria so far prior to either's evolution.

> Calling a pterosaur a dinosaur is an error of the same order of magnitude as saying that our species is a marsupial

I'd say it's more like the error of calling a tomato a vegetable. While it's true that from a phylogenetic perspective that pterosauria aren't dinosaurs, they still have many basal characteristics (relative to today's flying dinosaurs, the aves) that give them a certain dinosaur-like quality in the imagination. Besides, they're contemporaneous with the true dinosaurs. Grouping them with the dinosaurs is understandable. The grouping is incorrect under one classification scheme, but correct under another.

BTW: this site screws up copy and paste, appending marketing junk to any text copied to the clipboard. I wish it were possible to prohibit these clipboard shenanigans.

Tomatoes are vegetables. And yes, I see there is a comment lower down that tries to point out that tomatoes are fruits. But guess what, they're not mutually exclusive. That is because fruits are a scientific term, and vegetable is a common or culinary term. From Wikipedia:

"Vegetables are parts of plants that are consumed by humans as food as part of a meal. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, leaves, roots, and seeds. The alternate definition of the term vegetable is applied somewhat arbitrarily, often by culinary and cultural tradition. It may exclude foods derived from some plants that are fruits, nuts, and cereal grains, but include fruits from others such as tomatoes and courgettes and seeds such as pulses."

That makes sense to me. But, how about mushrooms? Do people consider mushrooms to be vegetables, or are there three different over-arching categories of food, meat, vegetables, and fungus? I'd argue that distinguishing between vegetables and funguses isn't very important, and that it'd be safe to lump all funguses into vegetables for purposes of food. I don't know if that's typically what's done, however.

If there's going to be three categories, I would think meat, seafood, and vegetables (including funguses) would be more useful than going by scientific kingdom.

People are strange and inconsistent. They name things without knowing their full history, and then those names sometimes persist well after they are known to be incorrect.

Mushrooms are not vegetables; they are fungi. Fish are vegetables, as long as they have scales and fins.

Seafood is meat, and mushrooms are their own thing (like a vegetable but not)

> I wish it were possible to prohibit these clipboard shenanigans.

It is in Firefox, at least:

  about:config 

  dom.event.contextmenu.enabled = false

  dom.event.clipboardevents.enabled = false

Great tip!

Thanks!

Besides black6's solution, my alternative is to use developer tools to copy the text directly from the DOM tree.

Tomatoes are vegetables under any classification scheme.

https://en.oxforddictionaries.com/explore/is-a-tomato-a-frui...

Nope, tomatoes are technically fruits, though they are commonly considered vegetables.

Just like pterosaurs are technically not dinosaurs, but are commonly considered to be in our culture.

> tomatoes are technically fruits

Tomatoes are quite obviously fruits. Most of the industrial tomatoes are tasteless because they're harvested well before they're properly ripe, but a ripe tomato harvested at the appropriate time is obviously (and tastes like) a fruit.

It's almost as if vegetable is an overly broad (and as such not particularly useful) designation in the common lingo, much like dinosaur ;)

How is this related to what I said? Fruits and vegetables are not mutually exclusive.

Fruit is a botanical classification (at least the way you're using it) whereas vegetable is a culinary one.

When they were building their taxonomy, why did not they name its level, that includes both what they now call "dinosaur" and pterosaurs "dinosaur", and come up with a different name for their "dinosaur", if it is a common conception?

You seem to think the word was in use prior to the development of taxonomy, but the word "dinosaur" began as a specific taxonomic term, coined by Richard Owen. From the outset, it was recognized that not all Mesozoic reptiles were dinosaurs.

If conformance to common usage is an important taxonomic principle, then maybe taxonomists should put the label "fish" in their taxonomies so that whales and cuttlefish are included, as these were commonly regarded as a type of fish prior to the development of scientific taxonomy? This example shows why this principle does not work in general: "fish" would then include a great many species - including ourselves - that are not regarded as fish by anyone.

Well, for starters, as you can see from the graphic, you'd be getting a lot more than just "pterosaurs" if you did that, given that they are in fact quite distantly related, with several other layers of non-dinosaurs inbetween.

The goal of creating the taxonomy was presumably to create clear categories for research and scientific publications. I doubt they cared what an average person called a dinosaur, like the author of this article seems to, so the issue you're worrying about probably didn't seem important.

It's almost as if the conception didn't come to be until _after_ the names for these things existed!

I doubt that specialists are keen to adapt their terminology to reflect popular usage and would much prefer things to work the other way around. It looks like the word we should be using is 'avemetatarsalians'?

If one can't pedantically correct people then why even bother being an expert.

I think the "common conception" comes from Land Before Time and Jurassic Park, it seems almost everything we learned about dinosaurs from those movies is wrong.

Edit:

I just looked it up and discovered both were made by Steven Speilberg...

Nah, pterodactyls and such were commonly taught to children to be dinosaurs before Jurassic Park and Land Before Time came out.

Source: was child before 1988.

Where do you think it originated then?

To be fair to Jurassic Park, I'm not sure its pterodactyls were explicitly claimed to be dinosaurs, and much of the film talked about non-dinosaur extinct species being resurrected as well (eg, ancient plant life).

Maybe it wasn't the filmmakers intent, but they have plausible deniability here. :)

Exactly. I am pretty certain, no such claim was made by the movie. And although it mixes a bunch or eras together, it does not claim to have just brought back dinosaurs.

Can you link to a source with some detail on what was wrong with those films? Particularly Jurassic Park?

https://www.theguardian.com/science/2009/feb/08/jurassic-par...

Or search: "Jurassic park wrong about dinosaurs"

This doesn't seem very strong to me.

OK, so I have been misinformed about velociraptor - I'll picture it smaller and with feathers. And brachiosaurus might not have been able to made a sound or stand on hind legs.

But I don't think that these relatively small details have left a generation woefully misinformed about dinosaurs.

If there are major things wrong with the film - if, for example, dinosaurs weren't as "bird-like" as the film made them seem (that seemed to me to be a major overture), then sure, I'd really like to read about that.

Look up what A t-rex looks/acts like now. No roaring, running, licking, had feathers and freckles:

https://www.mirror.co.uk/news/uk-news/rex-was-ginger-freckle...

https://www.nbcdfw.com/news/local/T-Rex-Likely-Could-Not-Roa...

https://www.scientificamerican.com/article/t-rex-couldnt-sti...

https://www.manchester.ac.uk/discover/news/tyrannosaurus-rex...

Ehh, they're using the name "Dinosauria" as evidence that people use "dinosaur" wrong. I'd say they're misunderstanding the word "dinosaur".

It's a bit like (though in reverse) how "canine" is often used for the Canis genus (dogs), but is easily confused for "canid" (the Canidae family) which includes foxes and tanukis.

This reminds me of the "fun fact" that people throw around about tomatoes being a fruit.

Really there are two sets of terms - culinary and botanical. Botanically tomatoes are a fruit yes, but they are also a vegetable. And in the culinary context you would never use a tomato like a fruit.

The English language is defined by it's usage, and the same word can mean different things in different contexts. Dinosaur is used commonly to refer to Pterosaurs in the "general" context, so a Pterosaur is a Dinosaur in that context. If you were instead a biologist talking in the context of academia then a Pterosaur would not be a Dinosaur.

I'm nitpicking but tomatoes are (sometimes) use as a fruit in culinary context: https://en.wikipedia.org/wiki/Tomato_jam

To be pedantic, the first Wiki link in that article goes to the Fruit preserves article[0], which begins with: "Fruit preserves are preparations of fruits, vegetables and sugar, often stored in glass jam jars."

So while tomato jam is a type of fruit preserve, not all fruit preserves are made of fruits (despite the name).

[0] https://en.wikipedia.org/wiki/Fruit_preserves

I enjoy thinking of salsa as a fruit salad.

It is a fruit.

The whole vegetable push was initially for taxes.

(https://www.goodhousekeeping.com/home/gardening/a20705757/ar...)

(https://www.businessinsider.com/supreme-court-tomato-is-vege...)

Also, the average Joe around the world is really really bad in plant related food classification. Given that a lot of cookbooks are written by non-culinary experts, I would take such culinary information with a grain of salt as to proper naming and classification. Culinary experts do refer to strawberries, tomatoes etc accordingly.

What is the scientific definition of a vegetable?

Culinary: Edible part of a plan that is not, or does not contain seeds (i.e. not a fruit).

Biology/Botanology: does not exist. Only the definition of fruit is of interest. Thus something that a cook would call a vegetable are classified into finer categories (e.g. leaves, roots etc).

> The English language is defined by it's usage

Speaking of which: I've been anxiously awaiting the day when dictionaries finally give up and declare "it's" as a valid spelling of "its".

> in the culinary context you would never use a tomato like a fruit

I'm not sure what it means to use something "as a fruit" in culinary context, but tomatoes are definitely used in many contexts that other fruits are. Tomatoes, avocados, lemons, limes, grapefruits are all used raw in similar savoury salad-y contexts, and there are plenty of fruits that are also cooked with.

On a tangential note, I'm still trying to wrap my head around the notion that a flying reptile the size of Quetzalcoatlus (believed to have wingspan on the order of 10 meters) could ever get airborne.

This has made me wonder if it's possible that juvenile Quetzalcoatlus could fly but adult Quetzalcoatlus could not. Natural selection would presumably select towards smaller and smaller wings on adults, but maybe this could be offset by a serious evolutionary advantage bestowed on juveniles from being able to fly.

I don't know of any bird existing or extinct with this kind of lifecycle, but maybe you can find something similar in insects?

No, pterosaurs had wings built out of hand bones, and hands develop their size early in vertebrates. Therefore if you've got the right proportions to fly as a grownup, you should be able to as a kid. Whether that was right to birth is still debated, but certainly they could fly from being young.

By contrast birds and bats use arm bones in their wings, and so cannot fly until nearly an adult. That imposes child care needs on the parents that are pretty severe if you are large.

Now when species compete, they usually don't do it head on. Instead each specializes on what it does better. Pterosaurs couldn't do much about the fact that feathers are more efficient flight surfaces than their hair. But they had one advantage - it was easier for them to grow big. And that is why at the end of their time, the last niche that they held was a freakishly big carrion eater. (And dinosaurs could make for some freakishly big carrion for them to eat!)

> No, pterosaurs had wings built out of hand bones, and hands develop their size early in vertebrates. Therefore if you've got the right proportions to fly as a grownup, you should be able to as a kid. Whether that was right to birth is still debated, but certainly they could fly from being young.

You've got the GP's question exactly backwards - they aren't questioning whether the juveniles could fly, only the adults. If you develop the full hand size early in life, and that supports flying with 20kg of mass, a 15kg juvenile is going to have a much better time of things than a 50kg adult. (Numbers pulled out of my ass, I'm not sure what the actual ones would be)

Bat's have hand wings. Their order Chiroptera means hand wing. Their wings are elongated hands and fingers.

https://www.researchgate.net/figure/Anatomic-structure-of-ba...

They may have been able to fly because, perhaps, the air pressure was different back then. 2 bar or more

http://levenspiel.com/wp-content/uploads/2016/02/DinosaurW.p...

Going back even further, there's giant insects. Bugs today are limited in size to the efficiency of their respiratory system. They don't have lungs like vertebrates. Air just sorta diffuses through their bodies. I you raise insects in a high oxygen environment, after a few generations they get bigger. The size of bugs before the dinosaurs indicate a higher oxygen content.

https://www.livescience.com/1083-oxygen-giant-bugs.html

I'm under the impression that a higher prehistorical concentration of oxygen in the atmosphere is widely accepted at this point. Higher atmospheric pressure is not something I've heard anything about though.

Wikipedia has a nice graph showing high and low estimates for the historical oxygen level: https://en.wikipedia.org/wiki/Geological_history_of_oxygen#/....

I don't think anybody is claiming that Earth gained extra nitrogen (how would it?). So, while it lost oxygen, it also had to lose some air pressure.

I imagine there was some huge pressure loss at the oxygen catastrophe.

My thought would be, when the asteroid hit, it blew away a large chunk of atmosphere with it.

You also need to account for CO2.

There is almost no CO2 on the atmosphere.

The idea of older individuals being flightless is specifically addressed in the Plos article linked at the top. Basically, the large individuals still have lots of flight-optimized characteristics that you would expect to have atrophied if they weren't flying.

From the referenced article [https://journals.plos.org/plosone/article?id=10.1371/journal...]:

> It is possible, however, that giant pterosaurs represent old, flightless individuals of a species that were capable of flight when younger, their flight anatomy simply being retained from a previous stage in their life history. However, if the maximum flight sizes suggested by Sato et al. [17] and Chatterjee and Templin [19] are correct at 41kg (5.1 m span) or 70 kg (6.65 m with ‘heavy’ estimates), then the largest azhdarchids would have grown up to six times the mass and twice the wingspan of their terminal flight size. It seems unlikely that enormous azhdarchids would continue to develop their physiologically expensive flight apparatus, and coincidentally with a mechanically appropriate scaling regime, throughout such extensive growth under flightless conditions. The same point is true, though to a lesser extent, for large Pteranodon that also bear obvious flight characteristics despite having exceeded the suggested wingspan limits of flight. If anything, the scaling regimes of pterosaur wings dictate that the flight characteristics of giant pterosaurs (the size of their deltopectoral crests, robustness of their joints) - become more exaggerated with size and age (e.g. [76]), precisely the opposite of what would be expected in animals that lost their flight ability as they grew older.

This doesn't help me understand the physics of large flying reptiles, but it does make a plausible argument that they were in fact real.

Useless fact but since where talking about naming things. The word helicopter is a combination of helix and pteron (spiral wing). https://en.m.wiktionary.org/wiki/helicopter

Greek helix (genitive helikos) + pteron "wing" (from PIE root pet- "to rush, to fly").

https://www.etymonline.com/word/helicopter

That page says 'helix : "a spiral thing", a word used of anything in a spiral shape (an armlet, a curl of hair, the tendril of a vine, a serpent's coil)' - though all these examples are helices, not spirals; I suspect the author(s) didn't know the difference.

Well you piqued my interest, what's the difference?

I note that Wiktionary, and the Oxford Pocket Dictionary (which I believe is what Google use), consider them to be synonyms.

For example this from the latter's definition of "spiral" -

"winding in a continuous curve of constant diameter about a central axis, as though along a cylinder; helical. synonyms: coiled, helical, helix-shaped, corkscrew, curling, winding, twisting, whorled"

A spiral is 2D, like the Archimedean spiral. A helix is 3D, like a spring, or DNA's double helix. Calling them Archimedean helix or DNA's double spiral would make no sense.

Dictionaries aren't a great place to find the actual meaning of words. :-) ..mathematical terms, anyway.

Mathematics isn't a great place to find the actual meaning of words, either, if by actual meaning you mean the meaning understood by the general native-speaking population.

As with the "dinosaur" definition; it's about domain.

"Spiral staircase" isn't wrong, it's that within geometry words have a greater specificity.

Related : a ladybug is not a bug. [1] Scientific nomenclature and common language often disagree!

[1] https://theamericanscholar.org/a-bug-is-not-a-beetle/#.W5-t5...

This article is incorrect, a pterosaur may not be a dinosauria but it definitely is a dinosaur.

Dinosaur has become a generic term. You can even refer to humans who have old-school ideas as dinosaurs.

Metaphorical use doesn't count as turning something into a generic term. You can call obstinate humans buttheads, and yet, etc.

This is more in the 'a gorilla is not a monkey' or 'a dolphin is not a fish' category. Getting this sort of thing wrong is going to get you torn apart by gangs of roaming five-year-olds on your next natural history museum visit.

Even though mammals are a subset of the descendants of things that are unquestionably fish, we don't call mammals fish, and we do call things fish that are of separate ancestry, so I feel there is kind of an arbitrary double standard here if we get pedantic about dinosaurs. There's no question that in general, categories of living creatures don't have to be monophyletic.

"Fish" is a bad category, or to be more precise from https://en.wikipedia.org/wiki/Fish#Taxonomy

> Fish are a paraphyletic group: that is, any clade containing all fish also contains the tetrapods, which are not fish. For this reason, groups such as the "Class Pisces" seen in older reference works are no longer used in formal classifications.

I think we mostly agree, because you wrote

> There's no question that in general, categories of living creatures don't have to be monophyletic.

But I think that the main effort is to make all the categories monophyletic, and drop/replace the other one when possible. Some non monophyletic categories are very useful in practice and they are keep to make communication easier.

The problem is that if you try to make "fish" a monophyletic category you must put "dolphins" inside them, because the dolphins are distant descendants of some fish (as you and me and all mammals).

But Pterosaur and Dinosaur are sibling categories, neither of them descend of the other. Using much smaller categories, it is like comparing penguins and orcas (both are black and white, both swim, both have to breath air, both eat fish), but neither of them descend of the other.

I disagree along with the sibling comments. While as it is apparent from the comments to this posts the misconception of pterosaurs/pterodactyls etc classification exists, there were never dinosaurs. I am guessing at some point, in certain parts or all around the world people start making the connection, it existed prior to humans, it must be a dinosaur (or you know they share a suffix). It is similar to a zebra and an alligator have four legs so they must be the same. The average Joe has a pretty distorted image of dinosaurs to begin with (e.g. raptors, T.Rex).

Think it like this: assuming you try to discuss about digital storage with a grandparent or old relative. And they say that an SSD is a HDD (sorry late can't think of a better example). To them it makes no difference they save stuff at the end of the day or something like that so might as well be the same. To you they function, are designed and behave differently. So to you a pterosaur is a long dead species, so might as well classify it as a dinosaur. To people who spend a bit of time to familiarize themselves, it is like calling humans marsupials [0].

[0] https://www.smithsonianmag.com/science-nature/why-a-pterosau...

I disagree. When used to call a human a dinosaur, it is an abstract term. People are fully aware that the referenced person is not actually a prehistoric reptilian. I think referring to all such prehistoric creatures as dinosaurs is problematic because it doesn’t allow for the same obvious distinction. How could one otherwise know if the article refers to all prehistoric reptiles or Dinosauria?

You're confusing the use of the word as a name for a group of animals with a its use as a metaphor.

I was half-joking; but I do think that when it comes to language, if the majority of people believe something to be true then that consensus is enough to make it true. Languages evolve constantly and the correct use for terminology should be determined by the majority of people.

Day-to-day terminology and scientific terminology don't necessarily have to match. There are examples of this in most fields of science and engineering; sometimes complex concepts have to be simplified for regular people.

The article linked at the top of this one is quite readable, a few technical terms aside. I recommend it. The referenced part about how pterosaurs launched is very near the end.

because pluto isn't a planet? I mean sure, inside the discipline knowing the distinction between an integer and an ordinal number matters, but outside? Less sure.

I'm going to keep mentally filing pterosaurs in dinosoar memory. I think 99% of the non-obsessives older than 12 will do likewise. Pluto came back from the dead, after all...

Pelicans seem to evolve from pterosaurs but ostriches seem to have come from theropods. Since those are both birds, I would guess pterosaurs and theropods are just as closely related as pelicans and ostriches.

Not quite. Birds, in general, appear to have evolved from a subset of theropods. They are in the same clade.

https://evolution.berkeley.edu/evolibrary/article/evograms_0...

https://blogs.scientificamerican.com/tetrapod-zoology/50-mil...

I'm really curious about where you learned that.

Natural history museum in LA. They have a big exhibit on theropods and pterosaurs and show the birds that possibly evolved from them. Birds are dinosaurs under all the usual biological classification schemes. Similar phenotypes, similar genotypes.

Are you sure it was "evolved from" and not "looks like"?

Because pterosaurs have no living descents, and all birds descended from therapod dinosaurs (even if birds were already widespread before the end of the Cretaceous).

Yeah it might seem that way but pelicans don't come from pterosaurs.

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