One of the key things to remember is that all the continents were connected during the Triassic, which is why we find fossils of some of the early dinosaurs on literally every continent.
By the Jurassic, Pangea had broken up into the northern super continent Laurasia and the southern super continent Gondwanaland. That's why you only ever find tyrannosaurs in the Northern Hemisphere.Another key thing, if you've been to the movies, is that most of the dinosaurs in Jurassic Park are from the Cretaceous.
Dinosaurs were around for hundreds of millions of years, so not all of them were around at the same time. For example, no T Rex ever saw a stegosaurus. T Rexes are closer in time to eating at Taco Bell than they are to eating a stegosaurus.
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| Which one is the dinosaur? |
So, what makes an animal a dinosaur?
It walked with it's legs under it (on land!).
It hard hard shelled eggs.
It had leathery or scaly skin (feathers are a form of scales).
The two major divisions are the Bird Hips (ornithichians) and the Lizard Hips (saurichians).
This class dealt with the Bird Hips.
These are broken down into "Tank" dinosaurs (stegosaura) like the stegosaurs and ankylosaurs, and "Beak" dinosaurs (ornithopoda), like maisaurs and triceratops.
Let's start with the main problem: yes, birds developed from dinosaurs. We have here bird hipped, beaked dinosaurs whose name (ornithopoda) means bird footed. These are completely unrelated to birds. I kid you not, the birds developed from lizard hipped dinosaurs. Evolution is funny like that sometimes...
So, tanks! These dinosaurs all had 4 legs, ate plants and were armored like, well, tanks. Most of them had offensive weaponry in their tails, either spikes (thagomizers) or clubs.This is a good place to mention that virtually all the common dinosaur names refer to groups of animals. All the stegosaurs in the picture are stegosaurs, but they came in a bewildering arrray of spikes, plates, and sizes.
The beaked dinosaurs were even more diverse. They also were plant eaters, but most of them walked on two legs. Later versions used 4 legs again, notably the triceratops, and some could use 2 or 4 legs, rather like bears today.These included the parasauralaphus with it's hollow crest (we used tubes of varying lengths to look at how this affected sound), all the "duck billed" hadrosaurs, the maisaurs, and the weird head-butting pachycephalosaurus.
We should point out that "beaked" dinosaurs had teeth behind those beaks, although only the most advanced late cretaceous ones could chew, something that requires a quite complicated jaw. The kinds of teeth (in all dinosaurs) show what they ate, and, because virtually nothing can eat teeth, dinosaurs replaced teeth throughout their lives, and teeth fossilize easily, we find lots of fossil teeth!
Fortunately, all the kids had brought their teeth, and, being omnivores, had teeth good for many kinds of food. Humans have Swiss Army Knife mouths! We used baby carrots and our different teeth to scrape, slice, crush, and chew the carrots.We also did our "amber" experiment. The kids made molds out of clay, then we used colored acrylic epoxy and embedded a fern, an insect or spider, and a feather in each one.
The kids' fossil gift this class was a piece of petrified wood from the late Triassic.
