BIOL211 Study Guide - Amnion, Dermal Bone, Dentin

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Published on 18 Apr 2013
School
University of Waterloo
Department
Biology
Course
BIOL211
Professor
CONCEPTS
Are dinosaurs endothermic?
Endothermic
- no growth rings in bones
- active running animal limb
anatomy
- fewer dinosaurs (predators)
than prey
- stable isotopic composition is
consistent with high body
temperatures
Ectothermic
- no living reptiles are
endothermic
- no elaborate nasal bones to
conserve moisture and heat
Mass Extinctions of
Vertebrates
- end of Cretaceous Period (65 mybp)
most recent mass extinction
- at least 5 mass extinctions during vertebrate
evolution
- most severe was end of Permian era (250 mybp)
due to volcanism and wildfires
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Time Periods
Metatherian versus Eutherian
reproduction
- eutherians are placental mammals in uterus (i.e.
shrew)
- metathera are marsupial mammals in pouch (i.e.
opossum)
Mesozoic Continents
- marsupials originated in North America, invaded
Eurasia, South America, Antarctica, and Australia
- Eutherians originated in Eurasia and displaced
marsupials invated South America late and never
made it to Antarctica / Australia until introduced
there by humans
- One marsupial (the opossum) recently reached
Ontario after reinvading North America from South
America
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Microlecithal Eggs
(example: Amphioxus)
Zygote to Blastula
- Radial, complete,
equal cleavages
- Leads to hollow space
(blastocoel)
Gastrulation
- invagination, creates
endoderm and
ectoderm with
mesoderm in middle
(on dorsal part of
endoderm)
Neurulation
- notochord will
develop at mesoderm
- notochord induces
formation of neural
tube
- embryo is now a
neurula
Mesolecithal Eggs
(example: Amphibian)
Zygote to
Blastula
- complete, markedly
unequal divisions
- larger cells on one side
(vegetal pole), blastocoel
towards animal pole
- more yolk, bastula is
several cells thick, small
blastocoel
Gastrulation
- gastrocoel highly
modified to
accommodate all the yolk
- splitting of coelom
instead of evagination
Neurulation
- mesoderm formation
starts dorsally at
notochord and is
partitioned into 3
sections on each side
Macrolecithal Eggs
(Example: Reptiles)
- incomplete cleavage;
eventually lead to patch
of flat cells called a
germinal disk
- blastula = layer of cells
on a mass of yolk
- separation of germinal
disk into two layers,
rather than process of
involution
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Document Summary

Active running animal limb anatomy fewer dinosaurs (predators) than prey stable isotopic composition is consistent with high body temperatures. No elaborate nasal bones to conserve moisture and heat. At least 5 mass extinctions during vertebrate evolution. Most severe was end of permian era (250 mybp) Eutherians are placental mammals in uterus (i. e. shrew) Metathera are marsupial mammals in pouch (i. e. opossum) Eutherians originated in eurasia and displaced marsupials invated south america late and never made it to antarctica / australia until introduced there by humans. Gastrulation (blastocoel) invagination, creates endoderm and ectoderm with mesoderm in middle (on dorsal part of endoderm) Blastula complete, markedly unequal divisions larger cells on one side (vegetal pole), blastocoel towards animal pole. More yolk, bastula is several cells thick, small blastocoel. Gastrocoel highly modified to accommodate all the yolk splitting of coelom instead of evagination.

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