There were no aquatic dinosaurs, there were Mosasaurs, Plesiosaurs, and Pliosaurs (plus a couple smaller groups) none of which were part of Dinosauria.The dolphin skeleton is very different from the emu skeleton.

Variations to the plan are just adaptations to different environments. The commonality is due to having a common ancestor in the Cambrian about 500 million years ago Thanks for the reply, but if I may say so you’re being a bit picky: a. Originally Posted by One beer So, from what you say, am I right in thinking that all animals with internal skeletons were/are derived from the same basic skeletal form?If so, I find that very interesting indeed. All are different from the ray/skate skeletons.

Paleoichneum did not trash you.In fact, s/he never mentioned you at all.If you feel personally insulted by someone correcting your posts, then you are going to have a hard time on a discussion forum. Mammals are modified versions of therapsid skeletons, which are modified versions of amphibian skeletons, etcI think one of major things to do is start thinking of us as modified fish, and not of everything else as modified humans. Originally Posted by One beer Ok, fair enough. Accuracy is important.

Has no other internal skeleton form ever appeared on earth – only derivations of the same one?OB I think that’s one part of the human body plan that works quite well. How come no other skeleton types or designs evolved?OB Oncea major success evolves it is tricky for any other solutions to get a look in. Once a significant advance is made the carriers of that genetic variation out compete any alternative ones. Originally Posted by One beer
It’s just that you got my hackles up because you spent 4 lines trashing me… Originally Posted by sealeaf There is probably no particular environmental drawback to having 6 toes In Norfolk it is almost mandatory. Throwing helped us to do more hunting. »The ability to throw at very high speeds is unique to humans. This has always seemed to me to be a bit of an « afterthought », but it obviously works alright.

I realised that we must have all come form a common ancestor, but my question was why? Why are there not any other animals with different skeletons on earth either alive today or in the fossil record?Just to be clear; when I say different,I mean completely different, not just different sized elements of the same basic 206 bone structure. That’s my two cents worth. There were no aquatic dinosaurs, there were Mosasaurs, Plesiosaurs, and Pliosaurs (plus a couple smaller groups) none of which were part of Dinosauria.The dolphin skeleton is very different from the emu skeleton. Expansion of knowledge is important.

Has no other internal skeleton form ever appeared on earth – only derivations of the same one?OB Almost all basic animal body plans are derivitives of one of the body plans which emerged in the early to middle Cambrian. No need for the put downs.Is the middle one a skate/ray?OB The post garnered three or four Likes, so apparently others disagree with your assessment. Have no fossils . of other skeleton forms ever been found? …was a question, (well, four questions).Simple answer (to the first part) would have been yes, with pictures of some examples.

I’m sorry you feel Paleoichneum’s « couple of points » were picky. The emu’s hand and finger bones have grown to very different sizes to the dolphin’s in order to form wings, (albeit an emu can’t fly any more). Your declared fascination with the subject might have been expected to generate gratitude for all of the post, not just parts of it.

Is it the most efficient way of doing it though – perhaps this arrangement gives a high degree of shock absorbancy?OB Both are very different from the sea turtle skeleton. Both are very different from the sea turtle skeleton. I do understand your points, but i was pointing out that its a fair bit more complicated then you are suggesting. Paleoichneum was not trying to put you down, but add to your knowledge. It’s a science forum.

Looking at early Devonian fish and early Carboniferous amphibians show that generally speaking mammals have a simplified modified version of the older plans. There really has been no other opportunity or major extinction event large enough with the right conditions for a non-chordate endoskeleton to emerge. The skeletal form here on earth is clearly a very successful arrangement. Originally Posted by One beer I realised that we must have all come form a common ancestor, but my question was why?

Why are there not any other animals with different skeletons on earth either alive today or in the fossil record? I thnk sealeaf has probably nailed this. Accuracy is important. Are these modified ribs, or does it have a different, unique skeleton to ours? I don’t know what the skeleton of a ray is like.

The skate is interesting – it has those bones in it’s side flanks. I’m sorry you feel Paleoichneum’s « couple of points » were picky. The number of digits on the limbs sees to be more variable.

Is it actually different to ‘ours’ or just very extensively modified?OB Every « book about dinosaurs » I opened as a kid showed pictures of animals on the land and in the sea, so I think that if I called them ‘aquatic dinosaurs’ you would know what I meant.Secondly, to quote myself: Has there been no other skeleton form on earth, and if not do we know why? Is ‘ours’ just so successful that everything else died out. A dolphin does seem very different to an emu and a sea turtle, but their skeletons have all the same bones, just that each bone is a different size or fused with others to specialize the specific role of the animal. The post garnered three or four Likes, so apparently others disagree with your assessment.

Cats have very small collarbone that dont do much, and in combination with the looser binding of the skeletal elements can usually squeeze through a space they can fit their head through, something the vast majority of us cant do. OK, yes lobsters and crabs too have external skeletons – I was not saying they didn’t – but surely you understood my point?b. We can throw much faster than our closest living relative – the chimpanzee – which can only reach speeds of 20mph compared to 90mph that many professional athletes can reach. »BBC News – Origins of human throwing unlocked »The ability to throw was one of a handful of changes that enabled us to become carnivores, which then triggered a host of changes that occurred later in our evolution, » Lieberman said. « If we were not good at throwing and running and a few other things, we would not have been able to evolve our large brains, and all the cognitive abilities such as language that come with it. I suppose the planet defined, it in a way?I wonder if the skeletal form on other planets would be the same or completely different?For example, our upper limbs are connected via shoulder blades which ‘float’ on top of our rib cages, held in place with muscle, cartilage and the collar bones etc. Have no fossils of other skeleton forms ever been found? …was a question, (well, four questions).Simple answer (to the first part) would have been yes, with pictures of some examples.

I would probably locate the upper limbs to the backbone with a more positive joint – onto the vertebrae – via something similar to a pelvis like the lower limbs are. The molecules in any pecursor system would simply be food for one or other of our relatives. The chordate plan was successful because it included a brain and it allowed for the development of an internal support (spinal chord), increasing the potential size of the organism.

OK, I was not aware that snakes had a vestigial pelvis, but don’t they have many more vertebrae and ribs than the mammals, so surely it’s a different skeleton, or is it a modification of ours?c. Originally Posted by Alec Bing Well, shoulder flexibity makes it easier to reach overhead, to throw things and to use your arms for attack or defense. They don’t get criticized for this, yet I get criticized for not knowing the correct word. Every « book about dinosaurs » I opened as a kid showed pictures of animals on the land and in the sea, so I think that if I called them ‘aquatic dinosaurs’ you would know what I meant.Secondly, to quote myself: Has there been no other skeleton form on earth, and if not do we know why? Is ‘ours’ just so successful that everything else died out.

Originally Posted by One beer . It’s a science forum. It’s the same reason new forms of life stand little or no chance of emerging by abiogenesis. insects are not the only animals with external skeletons.Why are snakes excluded from this, as they also have a pelvis, especially in some fossil groups. Originally Posted by One beer Thanks for the reply, but if I may say so you’re being a bit picky: – but surely you understood my point? OK, but you surely knew what I meant? let’s not be aplayground bore here.

I think the answer involves the basic process of evolution. They are all adaptations of the general chordate body plan. of which the amphibians and fish are much closer to the ancestral from then lizards so going with the 206 count is not really the right starting point. But there must be some good reason for the current loose arrangement to have evolved.OB I pointed out inaccurate information that was seemingly used in the opening question. Aquatic dinosaurs, OK, but you surely knew what I meant? let’s not be a playground bore here.d. I probably didn’t phrase my question very clearly.

A bat and a giraffe too each have the same basic skeleton, but the bat has very long thin finger bones to form wings, and the giraffe has very long neck vertebrae, but still only seven of them.e. All vertabrates are decended form one common ancestor with a skull, vertral column, and four limbs. Well this is exactly my point. No need for the put downs.Is the middle one a skate/ray?OB I’m not trying to be demeaning, just trying to inform. yes the middle is a skate Expansion of knowledge is important.

Accuracy is important. Expansion of knowledge is important. Point taken, but on here there are many posts written by folk who cannot spell, cannot correctly capitalize, or structure sentences. I probably didn’t phrase my question very clearly.

It’s just that you got my hackles up because you spent 4 lines trashing me before even starting to answer my (badly put) question.The skate skeleton certainly looks like an « alien », and completely different. It most likely is not the most efficient. After that point, major nodes of modification radiation have occured in each body plan over the eons, while several body plans, such as the marrellomorph and dinocaridid arthorpods, and the hallucigeniid ?onychophorids? have gone extinct. Most lizards and fish have many more vertebra then mammals, so all you need do is remove the pelvis and you have a snake. There is probably no particular environmental drawback to having 6 toes.

Ok, fair enough. The commonality is due to having a common ancestor in the Cambrian about 500 million years ago The skate is a modified version of a shark skeleton. Well, when something works… They don’t get criticized for this, yet I get criticized for not knowing the correct word. Thank you.

Point taken, but on here there are many posts written by folk who cannot spell, cannot correctly capitalize, or structure sentences. Thank you. Ah, well that could be the reason for movable upper limb joints right there.If I was designing a skeleton. The post garnered three or four Likes, so apparently others disagree with your assessment. Originally Posted by One beer It’s a science forum.

Is it actually different to ‘ours’ or just very extensively modified?OB I did not say anything about you, or trash you. But there must be some good reason for the current loose arrangement to have evolved.OB Well, shoulder flexibity makes it easier to reach overhead, to throw things and to use your arms for attack or defense. So, from what you say, am I right in thinking that all animals with internal skeletons were/are derived from the same basic skeletal form?If so, I find that very interesting indeed.

I’m sorry you feel Paleoichneum’s « couple of points » were picky. It’s just that you got my hackles up because you spent 4 lines trashing me before even starting to answer my (badly put) question.The skate skeleton certainly looks like an « alien », and completely different.