World of Dinosaurs/Dinosaur Clades

SAURISCHIANS.
"lizard hips"
This clade includes theropods and sauropods.
Theropods.
Sub-clades within Theropods.
These are groups that we want to be able to distinguish and read about in cladograms.
Sauropodomorphs.
"Lizard foot-shaped-ish". Long-necked dinosaurs are in this clade.
Some of the most basal dinosaur fossils we have might be sauropodomorphs - paleontologists argue about this as they keep finding new fossils.
A good example is "Eoraptor" ("dawn thief").
Definitely a basal sauropod is the big, goofy "Plateosaurus" ("flat lizard").
Sauropods.
The more derived long-neck dinosaurs are proper sauropods.
Surprising things about Sauropods include:
Within Sauropods we can consider two sister clades.
Diplodocoids.
"Two beams".
These are long, long, long long dinosaurs!
Diplodocoids have long faces and peg-like teeth.
We will pay attention to two Diplodocoids in this class.
"Diplodocus", a classic example of the clade.
"Barosaurus", a Diplodocoid common in Utah from Jurassic rocks. It's on display in the Natural History Museum of Utah.
Macronaria.
"Big nose"
These are tall, bulky dinosaurus.
We will pay attention to two Macronarians in this class.
"Brachiosaurus", a classic example of the clade. It lived late in the time of dinosaurs.
"Camarasaurus", a Macronarian common in Utah from Jurassic rocks. There are LOTS of them in Dinosaur National Monument.
ORNITHISCHIANS.
"Bird Hips"
Welcome to a very important dinosaur category that has a very silly name!
Ornithischians include:
What traits distinguish an Ornithischian dinosaur from other dinosaurs?
Genosaurs.
"Cheek Lizards"
This clade includes the most recognized plant-eating dinosaurs, except for the long-necked Sauropods.
Chewing is a derived trait in dinosaurs, and this is the clade that gets it!
Genosaur clades include:
Thyreophorans.
"armor bearer"
Derived thyreophorans are easily recognized by their gnarly body armor: Stegosaurus, Ankylosaurs, etc.
Dinosaur body armor is made from scutes (pronounced "scooooooooooots", as in "Hey let's get some of those scooters and go to Yoko."), which are bones that grow right out of the skin!
Our favorite basal thyreophoran is "Scutellosaurus", aka "scute lizard" aka "skin bone lizard".
Eurypoda.
"wide foot" Honestly I don't understand this name because their feet aren't, like, that wide, but I guess compared to the more basal dudes like "Scutellosaurus" it fits.
Lots of traits distinguish this clade but the coolest one is their bony eye sockets. Although scutes grow out of skin, on the skulls of these animals that scutes can tend to collide and grow along with the skull bones. Also a lot of the skull bones fuse together and get thick and wide, which is very different from the theropods and sauropods. A consequence of this that's easy to see on a skeleton in a museum is the fused bony socket around the eye - it's serious.
Also - obligate quadrupedalism. Eurypods walk on four legs, unlike basal thyreophorans and other basal dinosaurs.
But then the two main groups of eurypoda go very weird and different directions with the whole scute business.
Stegosaurids.
"roof lizard" Stegosaur dinosaurs have big plate-shaped scutes on their back.
Different species of stegosaurids are distinguished easily by their wacky combinations of plates and spikes. Some have spikes on the tail, some have spikes on the shoulders, and all look like no one was taking their lunch money easily.
General observations and interpretations about stegosaurids:
Ankylosaurids.
"fused lizard"
Ankylosaurs look a little less flashy than stegosaurs from a distance, but they have lots of wacky derived features with ecological interpretations.
Cerapoda.
"horn foot"
What's this? An extra clade that is a NODE joining the branches that lead to duckbills and to horn-faces.
Duck-bills and horn faces have these features in common, which they get from a last-common ancestor:
The name horn-foot can refer to the hoof-like toes that form in the derived members of this clade.
By now we are starting to notice that a lot of clades are named for DERIVED traits that show up in their famous members, so sometimes the name of the clade doesn't match to the trait that shows up on the branch leading to that node and joining all those animals via mutual inheritance.
Ornithopods.
"bird foot" "(are we sick of bird-this and bird-that yet? sheesh!!)"
Better-known as Duck-Billed Dinosaurs!
Duckbills and iguanadons have derived features for eating plant material.
Duckbills and Iguanadons probably mostly walked on two legs, but could also support their weight on their front legs.
The ecology of derived duck-bill dinosaurs is really well known from some excellent fossil examples of nests, and even from whole-body fossils from settings where the soft-parts preserved a bit, like a mummy.
Marginocephalia.
"edge heads"
This group includes very recognizable and less-familiar animals. What they have in common is stuff on the edges of their heads.
There are two main sub-clades in Marginocephalia.