EPS SCI 17 Lecture Notes - Lecture 13: Ornithopod, Stygimoloch, Herbaceous Plant
26 May 2018
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Lec 13: The Cretaceous - The Problem of Diversity
May 17
BIG QUESTION: Many different species lived side by side, and appear to fill similar ecological
niches. How was this possible?
CLIMATE IS CHANGING
●Triassic Paleogeography
○not very hospitable to dinosaurs (as very hot and dry towards centers of land)
○equatorial deserts
○continents mostly connected together
○large fluctuations in weather due to large continuents
○temperatures much hotter than today
●Jurassic Paleogeography
○Pangea is breaking up
○subduction still occurring off the west coast of North America
○allows for more diversity in dinosaur types
●Mid-Cretaceous Paleogeography
○western U.S. as island ‘continent’
■interior seaway in North America due to high sea levels
○less fluctuation in climate, and stable tropics/subtropics into high latitudes
●Late-Cretaceous Paleogeography
○retreat of interior seaway connects east & west North America
○Antarctica starting to build ice (as it drifts farther apart) → sea levels drop and
shallow oceans begin to retreat
○also allows for more diversity
THE RISE OF ANGIOSPERMS
●angiosperms (“flowering plants”)
: occupy many habitats and grow relatively quickly.
spread through pollination (rise during Cretaceous)
○includes trees (ex. beech, maple, oak, magnolia)
○still no grasses → herbaceous shrubs fill the ground cover niche (ex. hops,
buttercups, nettles)
●Gymnosperms vs. Angiosperms
Document Summary
Not ve y ho"pitable to dino"au " (a" ve y hot and d y towa d" cente " of land) La ge fluctuation" in weathe due to la ge continuent". "ubduction "till occu ing off the we"t coa"t of no th ame ica. Allow" fo mo e dive "ity in dino"au type". Lec 13: the cretaceous - the problem of diversity. Big question: many different species lived side by side, and appear to fill similar ecological niches. Inte io "eaway in no th ame ica due to high "ea level". Le"" fluctuation in climate, and "table t opic"/"ubt opic" into high latitude". Et eat of inte io "eaway connect" ea"t & we"t no th ame ica. Anta ctica "ta ting to build ice (a" it d ift" fa the apa t) "ea level" d op and. Angiosperms ((cid:343)flowering plan s(cid:344)) : occupy many habitat" and g ow elatively quickly. Include" t ee" (ex. beech, maple, oak, magnolia)
