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