Hacker News Reader

Comment by irrational | Hacker News Reader

Since birds are dinosaurs, don’t you mean “preparing to hatch like a dinosaur”?

Obviously a dinosaur will hatch like a dinosaur. Thats tautological.

The new finding is that that individual dino appeared to be hatching in the same way present day birds do. (As opposed to for example how crocodiles do.)

The article states that this behaviour was not previously observed in dinosaur fosils therefore it was not known which way they hatched exactly.

No, it says in the article that what is surprising, is that the embryo was lying in the egg like a bird, _not_ like previously found dinosaur embryos, which lied like crocodiles/reptiles.

So, it was preparing to hatch like a bird, unlike other dinosaur embryos found before.

Parent was making a pedantic comment; birds are a subset of dinosaurs. https://www.livescience.com/are-birds-dinosaurs.html

Birds are dinosaurs, but dinosaurs are not birds. If the article were about a fossilized mammalian embryo being born like a dog, you wouldn't say "since dogs are mammals, don't you mean born like a mammal?".

Dinosaurs are reptiles of the Dinosauria clade. Just because birds have an ancestry that stems from dinosaurs doesn't mean they are dinosaurs.

> Dinosaurs are reptiles of the Dinosauria clade. Just because birds have an ancestry that stems from dinosaurs doesn't mean they are dinosaurs.

In phylogenetic taxonomy: (1) that's exactly what it means, and (2) that's why Aves is within Dinosauria.

Except they're not within Dinosauria. Aves is within Sauropsida.

EDIT: I guess they're within a clade Avialae that is nested under Dinosauria. So yes, it looks like you are right.

You seem to be getting confused by Wikipedia’s treatment of lists of taxonomic categories, where it randomly excludes levels (particularly in sequences of clades) in the middle. If you read the actual description of taxonomic categories, or follow the chain, or use a source which doesn't randomly omit levels in lists, or consider why Dinosauria and one particular branch at every level below it is not marked extinct, you would see that you are wrong.

“Like an avian dinosaur” would be the modern terminology, I believe

(Edited:) Yes, but that’s just a long-winded way saying ”like a bird”. This dinosaur was not itself a bird because birds evolved only after the K–Pg event.

>the dinosaurs that survived K–Pg were not avian

Doesn't the term "avian dinosaur" in some sense mean "survived K-Pg"?

Yeah, but not the other way around. But there’s semantic ambiguity with the term “avian” – I used it to mean “capable of flight” but it can also mean “member of the clade Aves”. The dinos that survived were not flying at that time , and not all survivors were in Aves; flight evolved in Aves only after K–Pg and other dinos that survived went extinct later.

(I edited my original comment to be more precise)

That does not jibe with my reading. Which is that there were certainly flightless birds that survived K-Pg (Palaeognathae, ostrich ancestors) and the dominant flying dinosaurs (Enantiornithes) died off, but Neognathae survived and was flight-capable.

Penguins, ostriches, and emus are definitely birds, definitely avian, and definitely not capable of flight (under their own power).

But not exclusively. There were pre-K-Pg avians, too.

“Avian” or “Avian dinosaur” just means a particular branch of dinosaur that gave rise to modern birds. As opposed to “non-avian dinosaurs”.

Sure, there would necessarily have to be pre-K-Pg avians for them to have been the only ones that survived. I just don't see how one could characterize surviving dinosaurs as non-avian in any way, but they apparently meant non-flying.

Perhaps, yes. My answer was intended as a somewhat tongue-in-cheek response :)

Reply on news.ycombinator.com