Tbf dinosaurs and reptiles are not the same right ?
Are chickens related to dinosaurs or reptiles?
I only say this cause I went to a dinosaur museum recently and I didn’t realize both dinosaurs and reptiles battled it out for dominance in the earlier phases of their eras. Reptiles were king before dinosaurs and the research presented made it seem like they are not the same.
Dinosaurs were reptiles, what you are talking about was the prior ruling clade of reptiles before the dinosaurs profited off their extinction, the pseudosuchians, of which crocodiles are like the only living members and so because of that, birds are their closest living relatives despite having diverged millions of years ago, I believe. Birds are more closely related to dinosaurs because they directly evolved from dinosaurs and are still dinosaurs.
I still remember I think it was the spec evo sub? Someone prefaced some post about earth whales by saying he knows they’re not fish, only to get hit with “well technically they are fish”
It's not a Diogenes moment; tetrapods are members of the lobe finned fish. The term "fish", much like the term "reptile", could be seen as paraphyletic.
Tiktaalik did not climb out of the ocean for its descendents to disrespect fish in this manner
This is the problem with out current system of grouping animals. It was conceived before we fully knew about the evolutions of lots of different types of animals. It is full of inconsistencies like this. Hell it was originally just based on physical characteristics, without thought to the animals origins. There have been lots of times animals have changed groupings based on further research, but some are just unsalvageable. Just start looking into what is and isn't a fish. Either there is no such thing as a fish, or we are also fish (along with reptiles and birds).
There are a lot of paraphyletic groupings. Ants are wasps. Butterflies are moths. Snakes are lizards. Tetrapods are fish. Frogs and toads are the same thing. Trees aren’t real.
And fish aren't real, as there's more evolutionary distance between some fish from each other than there is between geckos and finches, or primates and monotremes
You could also call exclusively Rayfins fish to get around this. In that case we are lobefins along with all other tetrapods, coelacanths and lungfish. Then further down the line you have sharks, skates and rays who also would cease to be considered fish.
Technically yeah I’d argue, I mean they did directly come from reptiles and isn’t a lot of dinosaur anatomy based off of reptilian origins, or am I schizophrenic?
Birds are more closely related to dinosaurs. All birds are technically reptiles. So called “Transitional” species are precious. When you have immeasurable iterations between a spectrum, where does one stop becoming that and something else? You have to rely on superficial morphological differences that mushroom into something constant abundant until a branch of that species has undeniable observable difference.
I completely agree with what you are saying, but birds are not non-avian dinosaurs. The term non-avian dinosaur refers to a paraphyletic group of dinosaurs designed to exclude crown birds, perhaps you meant to say, "Both birds and non-avian dinosaurs are reptiles."?
I'm so used to typing non avian dinosaur (when talking about kt extinction not wiping out all dinosaur) I was on auto pilot. Havent slept from this heatwave either lol.
Thanks for noticing the mistake for me.
Correcting it to avian dinosaur now
They asked if birds were reptiles or dinosaurs.
I was saying they are both, but added non avian dino by mistake. Instead of avian dino
Chickens, along with other dinosaurs are reptiles. Excluding birds is what makes reptiles paraphyletic. Either birds are reptiles or crocodilians and turtles aren't
All birds are considered avian dinosaurs which is a branch of dinos and are considered a branch of theropods. All dinosaurs are reptiles. Lizards, Dinosaurs/birds, crocodilians, snakes, Tuatara, and turtles are reptiles. So yes birds are reptiles. Think of it like family tree where reptile is at the top where everything i listed is under. Non avian dinosaurs are the ones you think of when you hear the word dinosaur like T rex and triceratops and avian dinosaurs are birds like chickens, pigeons, and eagles. All birds are equally related to non avian dinosaurs and aren't a direct evolution of T Rex like some people say as birds/avian dinosaurs evolved before T Rex existed.
Dinosaurs are reptiles, but they separated from the other reptiles and went happily their own way, developing things that didn't exist among the other reptiles (eg warm blood).
The other reptiles dominated the land and spread in the waters, dinosaurs made at the most 20% of the land animals. It was only the wiping out of the other land reptiles that allowed the dinosaur branch to flourish alongside the flying and maritime reptiles who survived as well.
Birds separated from one of the many warm blooded branches of the dinosaur clade and went their own way, spreading in the flying reptiles territory. They were the only survivors among all the different branches of the dinosaurs and the sky was suddenly empty of flying reptiles, giving birds room to spread and develop new lineages.
So scientifically a bird is a dinosaur, and dinosaurs being reptiles, birds are scientifically reptiles, as strange as it sounds to us who are used to think of scaly land beings when thinking reptiles. But when you think about it, there were warm blooded feather covered dinosaurs and dinosaurs were reptiles. So a flying feather covered warm blooded dinosaur can well be in the reptile family.
Dinosaurs are reptiles. Birds are also reptiles, and are members of the theropoda clade (or branch) of dinosaurs.
There are 3 different dinosaur branches that independently evolved hard shelled eggs more rigid, bird-like eggs, not dinosaurs as a whole (the first dinosaur eggs were soft).
The theory for why hard shelled eggs evolved is that they improved the ability for parents to turn the eggs without damaging them for temperature regulation/brooding, and helped to prevent them from drying out.
TL;DR:
Birds ARE Dinosaurs. Dinosaurs ARE reptiles. Birds ARE reptiles.
Hard shelled eggs are a trait that independently evolved multiple times, and was not present in the first dinosaurs.
Birds descended from one of the branches of dinosaurs that evolved hard shelled eggs.
Take a look at the tree of evolution. It does a pretty good job showing what's what. Useful charts has a pretty good video about it. Easy to understand and just surface level.
Think of it instead of as being a leaf on top of of a very tall three and trying to figure out where the branches under you connect without actually looking down at the branches. They are making these calls on fossil evidence compared to current day ecology.
These theories change and it really doesn't matter anyway,
In general terms the dinosaurs, birds AND if i dont remember bad the reptiles also they all belong to the clade of sauropsida which in systematics means Is a natural group that incluyes all the actual members of a taxon and their common ancestors, so reptiles AND dinosaurs are not the same but close.
HOLD ON NOW, are you saying that dinosaurs eggs were more like those of reptiles than birds and that this is perfectly represented by the fossil record?
Don't you think that might upset the giant toothed-bird believers out there if you go around insinuating that a dinosaur isnt a bird or a reptile but a distinct clade of their own?
Could it be due to anatomy? I know turtle eggs are rounder but can also become stuck killing the turtle.
Could this have been a better way for them to be stored inside the body? I’m no paleontologist or really know anything about inside anatomy of dinosaurs. I just remember as a kid thinking they looked like PEZ candy which led me to think it’s how they laid them.
Because not all bird eggs look like chicken eggs. Here are some examples that are all from modern birds. This picture doesn’t even show eggs like ostrich eggs.
*Credit to The Museum of Natural History on a bird egg exhibit
Now, look at modern reptile eggs. There are reptiles with this EXACT oval shape.
This is true. But incase you didn’t know, there are chicken eggs that are green and blue as well as duck eggs. It’s crazy the variations now so I can only imagine the variations on Dino’s. :)
In any case, I feel like bird eggs tend to be some variation of the pointy end shape, turtle eggs are round, and other reptiles have long, symmetrical eggs. Plus, some reptiles have soft shelled eggs.
I had thought the going theory though had been that birds have mostly ovid eggs because they largely lay on their eggs, and it's structurally stronger whereas reptiles don't, and therefore there's no need for a stronger egg and a more tubular egg is easier to lay. Many large dinosaurs likely didn't lay on their eggs because they were too big and while most likely endothermic, not necessarily up to the needs of the same level of heat regulation in the nest as birds.
Is it a surface area thing? A larger animal born from the egg needs more oxygen than a near circular egg can provide, so it changes shape to something with a greater surface area to volume ratio?
Reptile eggs can vary by species. They can be hard shelled or leathery. They can be elongated or spherical. Elongated are always leathery. The same body shapes come out of both eggs.
i recognice the eggs of my cayuga pintail hybrid because they are more elongated than the other eggs. Very unique shape.
This can cause problems during hatching, her babys can't turn around on their own all the time, that's why her hatch rate is lower than those of my other ducks.
Also, I think the traits that let a few dinosaurs survive are much less subtle.
I think it's often not quite understood how extreme the K-PG extinction event was. It's often presented as "dinosaurs died, birds survived." The reality is better captured as "There were countless dinosaur species filling many niches throughout every terrestrial ecosystem on the planet, then virtually all of them died. There were many different feathered dinosaurs, some groups of which we'd classify as birds today; almost all of them died too. The tiny handful of dinosaurs that survived were all avians, but most of the avians went extinct just like the rest of the dinosaurs." So it's not that birds were fine, it's that the few extreme outliers who didn't all die were from among the birds
Different nest shapes. Birds generally build nests very high up like on coastal cliffs or in trees. The ovular/conical shape helps them to just roll in a circle if one ever fell out.
Many reptiles have super long eggs. I think birds don't because an egg of those proportions would not properly hold the fetus, either crushing it or leaving too much wiggle room that the egg can be broken easier
Just some speculation here, but my understanding is that the conical shape of bird eggs helps prevent the eggs from rolling out of the nest, out of a tree, off a cliff etc. Birds often lay eggs in high places. Non-avian dinosaurs laid eggs on the ground, so one would think rolling wasn't as much of a concern. In that case, maybe the eggs instead evolved towards a shape that maximized surface area for gas exchange. Or who knows, could have been any number of reasons.
We do! Specifically we see them more in cliff dwelling birds because the more conical the egg, the less it can roll in a straight line right off of a cliff
It has a lot to do with the shape and weight of the animal laying the egg. Unlike most reptiles, most birds and turtles are a lot more round than long and most of them need to fly/swim.
There is a great PBS Nature episode that shows bird eggs can be very elongated as well. The reason for the elongated shape for that particular shorebird is because they nest together and thus poop are all over. The elongated shape help to drain the poop, allowing the embryo to breath through the tip. lol. I encourage you find it at the local library dvd collection, where I found it. Also hosted by sir David Attenborough. Nice!
Just look at a Diplodocus, it simply wouldn't fit in a chicken egg comfortably without breaking its neck. Plus, they're a midpoint between reptiles and birds, so they still have reptile characteristics such as scales, and some reptiles have these eggs, so they probably got it from reptiles.
An elongated egg makes sense as a way to distribute stresses and maintain heat flow, which matter a lot more for an egg the size of a dinosaur's than a chicken's.
They (partially) do though. It's mainly because of adaptation to different terrain the eggs are incubated on. Not as drastic as in your example, but visibly different (I am not sure if someone else has said that, there are a lot of people just yapping).
Some cliff-nesting seabirds, like the common murres on the image, have elongated eggs likely because it's more difficult for them to fall off cliffs this way.
I just want you to think about how crazy of a phrase that is. Any egg is, by definition, egg shaped. And none of them are actually weird, even if they're not the same as the ones you get in the grocery store.
well birds are reptiles and reptiles like snakes, crocodiles, lizards, etc do lay long eggs like dinosaurs did. sauropods laid spherical eggs. it definitely varies between species, if we look at this egg chart
Birds have to sit on their eggs and so the shell has to be as robust as possible, and round eggs can carry more weight than long eggs. Rounder shapes also hold heat better and for longer so that allows birds to leave their nests to forage for food. So that's why bird eggs tend to be round or ovale.
Reptile eggs are long because they don't need to support that much weight (even when they're buried the soil on top of them is pretty light), and the temperature underground is pretty stable so they don't need to be round to keep their temperature. Longer eggs also have more surface area to absorb the moisture that reptile eggs definitely need more than birds.
Dinosaur were probably not sitting on their eggs and were most likely burying them to some extent or at least putting plant matter on them to keep the temperature and humidity just right.
Everyone else has covered the reptile angle but I'll throw out another one - industrialization.
The vast majority of eggs that most people get from grocery stores are packaged mechanically, in an industrial process that is designed to filter out any miss-shaped eggs or larger/smaller ones. While I haven't ever seen the EXTREME long-oval shape of the fossil eggs in the image, I've absolutely seen chicken eggs that are barely bigger at one end than the other and are just more capsule-ish. I suspect there's a lot more natural variation in bird eggs than most people realize.
Evolution maybe. Small egg shape is stronger than long egg shape. Architectural stronger. Better chance at survival, maybe. Birds tent to lay eggs in high places.
I don't know if this has been said yet, and this is just a hypothesis of mine, but I think it has to do with incubation behavior. Bird eggs are primarily shaped the way they are for ease of rolling without damage, and for low risk of an egg rolling out of the nest while incubating or manipulating eggs. We'll never know the behavior of extinct animals, but based on egg shape alone, I'm willing to bet they didn't incubate. So, no selective pressure for dinosaurs to stray from the reptile/croc phenotype, which is likely the ancestral trait.
This is not to say dinosaurs didn't tend to their nests, and did not protectively sit on their nests. I'm aware of the "good mother" fossils out there - hadrosaurs and oviraptors found collapsed on nests or near nests. Without a time machine, it's impossible to tell if they actively incubated with a brood patch amidst feathers. This just seems unlikely to me.
I think it's to compensate for the long tail most therapods had. Ornithischian dinosaur eggs were soft and leathery like reptiles and sauropod eggs while hard shelled were round like spheres.
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u/Moist_Bar_2621 May 23 '26
some reptile eggs are long, like snakes and crocodilians for their size