Today we’ll be discussing some interesting aspects about Dinosaurs and the Extinctions that ended their reign on the planet. Interesting stuff. Also knocks out one more class this quarter to have documentation for.
The first dinosaur we will talk about today is Pachycephalosaurus (which I assume means hard headed or thick skulled lizard). For those that have seen JP movies the following image will remind you of what it looked like with skin and CG ;).
These little…well relatively little, they weren’t exactly things you could step on as a human, are pretty interesting when you take a look at their builds.
The top vertebrae in their spinal column locks in to the skull into what is called the “occiput”, this connection means that with their head down they (as the image above shows) have a perfect spinal alignment. Likewise their spine even has interlocking mechanisms so that if there is an impact they don’t slip out of place. They have pretty thugged out hips that are fused to that part of their spine which suggests that it transfers kinetic energy from their spine down through their legs and out to the Earth. From the evidence provided the appear to basically be bipedal versions of what class? That’s right:
While I imagine the Pachycephalosaurus is far more well kempt (they were picky about their looks…ok that’s probably not true), this is likely our modern analogy for the little buggers. However as stated in class (the real one I’m in not this fake study one I’m teaching), their heads don’t seem like they’d be suited for two dude dino’s to be headbanging to get some…well…banging done later. The rounded nature of their head means that they’d have to hit spot on to each other to not risk doing serious damage (which doesn’t seem to be the goal in most mating fights unless you are a pissed off hippo).
However that sort of pointed skull would be perfect for directing the full weight of the dinosaurs energy into say…the ribs or even a leg bone of a dinosaur. It would more than likely break it which is really all they need to do to stop an attacker from trying to gobble them or their family up.
Their skulls are even built in such a way that kinetic energy should travel around their brain instead of into it, so while you might think these guys would bash themselves retarded in fights they actually could have held up quite well with whatever cognitive level dinosaurs had.
In the same clade but a little further up we have the Ceratopsia, if that sounds to you like Triceratops then you are in luck because that’s essentially what I’m about to talk about.
Firstly we are transitioning from mouthy looking mouths to beaky looking mouths. They had wide cheeks, and dental batteries inside their beaky mouths. If you have seen an elephants tooth you’ll know what a dental battery is (it is what it sounds like I suppose). Interestingly the frill on the neck is not something they all had.
We’ll start with the Psittacosaurus which sounds like something out of Pokemon, and frankly looks like something out of pokemon. This is likely the earliest of the group, with bipedal motion but large front arms suggesting they could have easily been used for walking as well (a transitionary animal). Cute little buggers. Beat, cheeks, and the gambit except no frill.
Next you have the Protoceratops which gets us closer to the stereotype for the species. These buggers were something like the size of a hog, which means they still could have killed you if they wanted to. The males apparently had a bump on their nose (perhaps a future horn) that made them sexually dimorphic from their lady friends, I suppose this is handy for poking some lady Protoceratops that just won’t pay attention to you. In their front legs their long narrow scapulas may have functioned as another joint which is kinda neat.
Above is a skeletal layout of a member of the Ceratopsidae. Again we are looking at sexual dimorphism in the skulls of these animals, specifically the frills and horns, interestingly also it looks like not only predators were trying to pwn the frills but so were other Ceratopsidae. The frills were highly vascularized which means they probably had a covering over them. They tend to be lightly built with holes in their structure (skeletally). Their frills likely had multiple uses from mating rituals, to defense, to heat discharge. Truly a functional flap.
One final note on these fellas is that the bones in the back of their skull were not only fused for support but also ended in a ball joint which helped it swivel nicely. Cool stuff.
So lets move on to the idea of Endothermic and Ectothermic organisms. For those of us who went through public school you have hot blooded and cold blooded. Basically you have Endothermic creatures which generate their heat internally, they tend to also be called Homeothermic which means they are basically the same temperature all the time. Humans for instances are Endothermic and Homeothermic, so are basically all mammals.
Your other set of animals are Ectothermic, their heat is generated externally and they are considered Poikilothermic, which means their temperatures vary. Basically when it comes to dinosaurs we are not sure if they were Endothermic or Ectothermic, however the ones we are finding with feathers are almost certainly Endothermic as they use the feathers to insulate. On the flip side you have massive dinosaurs who might have cooked if they didn’t have optimized systems. Albeit really there isn’t much to say that a giant ectotherm would do much better.
Also certain dinosaurs have been found dead covering their nests, which suggest warm blooded (keeping the eggs warm).
And with that we’ll stop this part of studying for today because I have to go read a silly book for an exam I have tomorrow.