Lecture 10: Ceratopsian Dinos Flashcards
Ceratopsia: were they well studied? when did they first appear? Where?
Yes they were a well studied group, first appeard in late jurassic of Asia, mostly in cretaceous of North America and Asia, rare fragments from europe, great herds in alberta, Montana and wyoming.
What are ceratopsia defined by?
Defined by the presence of a rostral bone forming the upper beak
What are the main Genus’ of ceratopsia?
psittacosauridae, and the Neoceratopsia: basal neoceratopsians (including protoceratopsids and leptoceratopsids) and the Ceratopsidae
Were psittacosaurus quadrupedal or bipedal?
Biped
Were neoceratopsia quadrupedal or bipedal?
quadrupeds
What are characteristic features of ceratopsia
Rostral bone: unique bone at tip of snout leading to a parrot like beak, a skull that is narrow at the beak and flaring, deep in the cheek region
What are the features of their skull?
Frill is composed principally of paired parietal bones (on top of skull) strongly vaulted palate beneath the beak, separating nasal from oral cavity, folding of bones on tip of the head to from secondary skull roof, dental batteries
Ceratopsid diagnostic characters
shape and number of horns, and shape and size of frills and hook on back of frill, long spikes extending from frill margin
Pachyrostra
derived centrosaurines with thick bosses replacing horns
Ceratopsian discovery
1870-1880s: cope and marsh. They found parts of pelvis, some teeth and vertebrae. Horn cores from Colorado misidentified by Marsh as belonging to a prehistoric bison, skull of triceratops in wyoming
Finds in Alberta
1890’s-1910s: Lawrence Lambe (ottawa) centrosaurus, chasmosaurus, styracosaurus. Barnum Brown (new york) Anchiceratops, leptoceratops
Finds in Asia
in 1923 ceratopsian dinosaurs discovered in Gobi desert, psittacosaurus, protoceratops
Psittacosaurus
Means “parrot reptile”, parrot like beak with rostral nose, discovered in the Gobi in 1920s, hundreds of specimens, no skull frill, bipedal
Ceratopsid diversity
one of the fastest growing dinosaur famillies, over a dozen new species recognized in the past 5 years ( first asian ceratopsid, oldest north american ceratopsids) lumpers vs. splitters
How many complete and partial skulls of triceratops are there?
over 50
Torosaurus?
One of the largest ceratopsians, 7-8 metric tons, Frill is made of thin bony struts and skin, not solid bone, some think this is the fully mature ontogenetic stage of triceratops, not a different genus
Evolution
From small (1-2m) bipeds to large (5-10m) massive quadrupeds, only small and very basal ceratopsians in the late jurassic, basal neoceratopsians common in Asia through cretaceous, Ceratopsids first appear and are only found in late cretaceous, mostly in north america (rare exception in Asia)
Abundance in North America
make up ~25% of late cretaceous Canadian fauna
Feeding
herbivores, dense clusters of teeth in cheeks, teeth were replaced when worn, dental battery, sturdy coronoid process- a membrane bone on upper side of lower jaw to the back, lacking teeth. evidence for fleshy cheeks, good food processing within mouth. gastroliths found with psittacosaurus
Chewing muscles
strong muscles for high efficiency mastication, attached through the upper temporal opening to base of the frill, attached to a sturdy large coronoid process on the manidble
feeding position
Low browsing, no standing on hindlimbs, knocking down trees? diet: shrubby angiosperms, ferns, small conifers
Locomotion
comparable to rhinoceros, usually slow but able to charge, tracks are uncommon, 2-4 km/hour, max running speed 30-35 km/hr
Integument
quills or bristles on the tail of psittacosarus, scale impression from rest of body
Social behavior
interspecific: among different species, intraspecific within the same species, Interspecific: role of horns, protection against predator
