Dinosaur questions
- Thread starter SchwEnt
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It may have been possible for some dinosaur species to interbreed, but it likely was not common, the same way interspecies breeding isn't common today.
- Remember that a small percentage of the animals died in circumstances conductive to fossilization. There were probably many species that haven't been discovered yet and won't be discovered any time soon. Theories about organization, including species divisions will probably continue to evolve for quite some time. Many aspects of their behavior and biology will never be certain.
- There's been some suggestions dinosaurs were warm blooded, which would preclude them continuing to be classified as reptiles. This includes evidence of them tending their young, stegosaurus having generous circulation in their spinal crests (cooling purposes similar to an elephant's ears) and many species having similarities to birds in their pelvic area.
- There have been suggestions that specimens once thought to be two different species were in fact adolescents and full grown adults of the same species.
I've seen a dog try to mate with a shoe, so I'm pretty sure dinosaurs did at least try, especially if they had less evolved mating preferences. Their chances of success were probably similar, but it depends how we define the boundary between their species. It might be so that for us as observers the two interbreeding species seemed to be the same one. It's like asking whether T. Rex interbred with T.Rex.
Fossils of dinosaurs are plentiful, while all remains of say the Neanderthals fit in the trunk of a Mini.
And most of them were most likely not warm-blooded, except for transitional species that became birds. Birds have to keep their eggs warm from the moment they are laid, and there is no indication dinosaurs did the same. Scale-covered skin is probably not good for the job, anyway. Spinal crests can also heat the animal up faster on a cool morning, or they might have been the result of sexual selection.
Well, we know that many Coelurosaurs, a broad group of predatory dinosaurs, were covered with either hair-like proto-feathers or true feathers.
In addition, we have found a Heterodontosaur that was covered in quill or hair-like covering as well - Tianyulong. And Heterodontosaurs are not at all closely related to the other feathered dinosaurs. So this could imply either that:
A. Feathery or hair-like covering evolved at least twice among dinosaurs who were otherwise scaly
B. Proto-feathers evolved once and was lost in larger species (similar to how elephants, rhinos, and hippos are mostly naked today)
Now, considering the fact that pterosaurs, the flying reptiles that are among the nearest cousins to all dinosaurs, were also covered in hair, then it's possible that not only were dinosaurs primitively fuzzy, but that the common ancestor of pterosaurs and dinosaurs was as well.
But again, maybe these coverings evolved multiple times independently. But, to explain pterosaurs we have to postulate three independent emergences of hair or feather-like integuments among archosaurs (the group that includes dinosaurs (including birds), pterosaurs, and more typically "reptilian" creatures like crocodiles).
I should add that it is plausible that any of these hairy or feathery creatures was endothermic or warm-blooded. Notice the two possibilities raised above have different implications. In one, warm-bloodedness evolved twice or more among dinosaurs, and three times among dinosaurs and pterosaurs. In this scenario, a couple of branches of dinosaurs including Coelurosaurs and Heterodontosaurs would have been endothermic while other dinosaurs would have been cold-blooded. In the alternative theory, it evolved once, in the ancestor of dinos, which would make warm-bloodedness the primitive condition for the entire group - which would still not preclude the possibility it was lost in some lineages thereafter.
In addition, we have found a Heterodontosaur that was covered in quill or hair-like covering as well - Tianyulong. And Heterodontosaurs are not at all closely related to the other feathered dinosaurs. So this could imply either that:
A. Feathery or hair-like covering evolved at least twice among dinosaurs who were otherwise scaly
B. Proto-feathers evolved once and was lost in larger species (similar to how elephants, rhinos, and hippos are mostly naked today)
Now, considering the fact that pterosaurs, the flying reptiles that are among the nearest cousins to all dinosaurs, were also covered in hair, then it's possible that not only were dinosaurs primitively fuzzy, but that the common ancestor of pterosaurs and dinosaurs was as well.
But again, maybe these coverings evolved multiple times independently. But, to explain pterosaurs we have to postulate three independent emergences of hair or feather-like integuments among archosaurs (the group that includes dinosaurs (including birds), pterosaurs, and more typically "reptilian" creatures like crocodiles).
I should add that it is plausible that any of these hairy or feathery creatures was endothermic or warm-blooded. Notice the two possibilities raised above have different implications. In one, warm-bloodedness evolved twice or more among dinosaurs, and three times among dinosaurs and pterosaurs. In this scenario, a couple of branches of dinosaurs including Coelurosaurs and Heterodontosaurs would have been endothermic while other dinosaurs would have been cold-blooded. In the alternative theory, it evolved once, in the ancestor of dinos, which would make warm-bloodedness the primitive condition for the entire group - which would still not preclude the possibility it was lost in some lineages thereafter.
The Neaderthals were just a subspecies of Human that lived for several hundred thousands of years while the Dinosaurs were an entire group of animals that existed for over a hundred million years. Of course there are more Dino bones.
However, the sparse comment means most dinosaurs that ever existed never were fossilized. There were probably entire groups of dinosaurs we will never know about.
J
Jetfire
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Until we put new tires on the DeLorean and go back...
This is like asking if Cro-Magnons and the Neanderthal got busy. The rule is that if it moves...
Comes up with a message that it won't play outside the UK.
The had weak engines, but could certainly reach 88 miles an hour, they topped out at around 110 miles an hour.
What they didn't have were speedometers that went past 80 miles an hour but only due to certain laws and restrictions in the 80s.
As someone else noted any fossilisation requires a pretty remarkable set of circumstances which is why it helps to have a species around for millions of years and many fossils result from disasters like landslides, flash floods, etc.
I don't understand where your second claim comes from as there have been brooding dinosaurs found more than once so your claim that there's no indication they did the same is completely false as is the idea that all dinosaurs had scaly skin, though someone else addressed that point.
Evidence suggests that dinosaurs were quite active animals and given they lived in every part of the globe it's unlikely they were ectothermic animals.
Evidence suggests that they originally evolved in the tropical environment of a super continent nowhere near the poles (that's why you find them on every continent now), in a climate so warm that to be ektothermic was no disadvantage. The disintegration of that continent, and exposure to colder climates later on turned some subspecies warm blooded, encouraged the growth of feathers, brooding, and upbringing. Only eight different species of dinosaur fossils have been found on Antartica so far, none of them younger than 100 million years. When it started to get real cold. No problem for todays population of warm-blooded birds and mammals.
The only family of animals with a more complete fossil record than dinosaurs is even far older, trilobites. Almost 50,000 species have been identified.
The only family of animals with a more complete fossil record than dinosaurs is even far older, trilobites. Almost 50,000 species have been identified.
Well, Antarctica wasn't always really cold and there were dinosaurs recently discovered from the late Cretaceous that lived near the North Pole. Ectothermy isn't that big a disadvantage today unless you're trying to live in places where it's cold year round. In fact there are a lot of advantages such as not needing to eat as much to stay alive or using energy to heat your body. None of this has much bearing on whether or not any dinosaurs were ectothermic.
What you're missing is that those species of dinosaurs living near the poles lived in ecosystems that were, as far as the fossil record shows, devoid of ectoterms like crocodiles, turtles, etc. This is highly suggestive that the environment was too cold for contemporary non-avian reptiles but not too cold for dinosaurs. The fact that dinosaurs but not "reptiles" could live in these high latitudes is suggestive of the fact that they were in fact warm-blooded to some degree.
People have been known to try inter-species breeding today. But perhaps that's better left to a different discussion...
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