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C O U R S E 
Dinosaur Paleobiology
Philip John Currie, University of Alberta
C O U R S E   L E C T U R E 
Notes taken on January 14, 2016 by Edward Tanguay
two key traits that distinguish ornithischians and saurischians
1. ornithischians have a hip with a pubic bone which points backwards
sometimes it has a projection that points forward, but they are usually short
resembles those of birds
this is an evolutionary convergence
birds belong among saurischian dinosaurs
plants are hard to digest
the backward-pointing public bone gave the ornithischians room for a large digestive track
2. a special bone in the lower jaw
predentary bone
no other animals have one
the predentary [pree-DEN-taree] is an extra bone in the front of the lower jaw, which extends the dentary (the main lower jaw bone), and coincides with the premaxilla in the upper jaw
together they form a beak-like apparatus used to clip off plant material
ornithischians were herbivores
gave ornithischians tool for slicing off plant stems
five main lineages
1. Hadrosaurs
Ornithopods started out as bipeds but Hadrosaurs probably walked on all four legs most of the time
had hand encased in a mitten of skin
crests on top of heads and flat heads
spikey thumb
2. Ceratopsia
four-legged dinosaurs
relatively short tails
an extreme form of skull bones coming out the back of the head
some had horns over their eyes
unlike duck-billed dinosaurs, had very narrow skulls
more like a parrot's beak
teeth had elaborated banks of teeth for sheering and crushing plant material
older forms don't have so many frills and horns as newer forms, but they still have a beak
Albert and Alaska
bony mass called a boss
above eyes
3. Pachycephalosauria
intelligent-looking because they have high-domed skulls
unfortunately, brain was not very large
most of the skull was solid bone
heads may have been used as battering rams
don't have long legs, so probably not that fast
skeleton is frail so not many exist
1920 a skeleton of Pachycephalosauria was found
4. Stegosauria
walked on all four legs
front legs shorter
skull small compared to rest of body
teeth were leaf-shaped and had narrow beak
plates or spikes along the back
bone that forms in the skin: osteoderm
earlier forms had spikes
later forms had plates
but even later forms had spikes at end of tail
5. Ankylosauria
armored dinosaurs
had osteoderms
walked on four legs
skulls were blocky
teeth were small
on some, the end of the tail had a bone which was used as a kind of club
two main branches of the dinosaur family tree
1. Saurischian Hips ("lizard hip dinosaur")
a. Sauropods ("long neck dinosaurs")
b. Theropods
common birds
2. Ornithischia Hips
a. Hadrosaurs
b. Ceratopsians
c. Pachycephalosauria
d. Stegosauria
e. Ankylosauria
armored dinosaurs