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56 Cards in this Set
- Front
- Back
The three periods of the Mesozoic.
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Triassic, Jurassic, Cretaceous
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The Triassic denotes _________ million years ago.
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250 mya
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The Jurassic denotes ___________ million years ago.
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200 mya
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The Cretaceous denotes __________ million years ago.
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140.
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Name two significant events in the Mesozoic.
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Pangaea breaks up
Sea-level change |
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At its peak warmth, ca. 100 my ago, Mesozoic climate was
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2 to 6 degrees C warmer at the Equator
> 20 degrees C warmer at the poles. |
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ca. _______ my ago lush ferns and alligators resided in Siberia.
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100
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Dinosoaur skeletons have been found north of ______________
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the arctic Circle in Alaska.
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What is the primary cause believed to have causes global warming during the Mesozoic?
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higher atmospheric CO2 levels – possibly by a factor of 4 from present levels
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what is the evidence of higher atmospheric CO2 during the mesozoic?
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Paleomagnetic evidence that sea floor was spreading faster at that time (can estimate the spreading rate by looking at the magnetic patterns on sea floor – spacing of magnetic reversals; faster rates would have resulted in faster subduction rates of carbonate sediments, which would have lead to increased rates of CO2 production and increased CO2 from mid ocean ridges
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Other possible influences/causes of warming during Mesozoic...
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During the height of the Mesozoic, equator-pole temperature contrast was only 20 to 30 degrees C, while today it is 50 to 60 degrees, so circulation was different – more mixing back then.
Absence of Polar ice, changing albedo of regions, warming them |
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Two reasons for the higher sea-level in the Mesozoic:
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climate warms
increased tectonic activity |
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Early Mesozoic dominated by ______, _______, __________, and others not widely seen today
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ferns, cycads, ginkgophytes
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Modern gymnosperms (e.g. conifers), first appeared in their current recognizable forms in the ___________.
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early Triassic
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By the middle of the __________, the earliest angiosperms (flowering plants) had appeared and began to diversify - became dominant.
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Cretaceous
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From the Carboniferous--Permian = _________ plants
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big spore bearing plants
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During the Mesozoic the evolution of _________ plants was seen.
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pollinating
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Early Mesozoic -Cycads,.Ginkgoes, Seed Ferns, Conifers =
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seeds, but no flowers
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Cretaceous = what kind of plants?
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Flowering plants (angiosperms) with enclosed seeds
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Name the four reptile groups of the Mesozoic.
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Anapsid, Diapsid, synapsid, euryapsid
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Describe anapsid.
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one orbital lobe, no temporal lobe
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describe synapsid.
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one orbital lobe, one temporal lobe (lower cranium)
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describe diapsid.
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one orbital lobe, two temporal lobe.
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describe euryapsid.
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one orbital lobe, one temporal lobe (higher cranium)
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Anapsids gave rise to the ___________.
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synapsids and diapsids
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diapsids gave rise to the ___________.
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euryapsids.
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synapsids gave rise to the ______________.
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therapsids.
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therapsids gave rise to the ____________.
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cynodonts.
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cynodonts gave rise to _______________.
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mammals.
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a pelycosaur (fin back) is an example of a _____________.
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synapsid.
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What was the first bird?
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Archaeopteryx
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List the four criteria of a dinosaur:
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1. belong to the mesozoic era
2. reptiles 3. terrestrial 4. parallel gait (not sprawling) |
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List the two groups of Dinosauria:
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Saurischian and Ornithischian.
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Two groups of Saurischian:
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Theropoda and Sauropodomorphs
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Theropods =
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Tyrannosaurus
Deinonychus |
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Sauropodomorphs =
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Diplodocus
Apatosaurs |
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The five groups of Ornithischian:
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Ceratopsians
Stegosaurs Ankylosaurs Pachycephalosaurs Ornithopods |
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Ceratopsians =
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Tricerotops
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Ornithopods =
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Maiasaurus
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What are some of the proposed causes of the Cretaceous/Tertiary (K/T) Extinction?
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Asteroid impact
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Effects of the asteroid impact that caused the Cretaceous/Tertiary (K/T) Extinction?
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volcanic activity
climate change sea level changes |
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Predatory dinosaurs =
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theropods
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Theropods =
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Ceratosaurs and Tetanurans
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Tetanurans =
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Carnosaurs and Coelurosaurs
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very large Tetanurans w/ short necks and small forelimbs
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carnosaurs
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small Tetanurans, long-necked w/ long forelimbs
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Coelurosaurs
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Primitive theropods
Skeletal elements in hind limb fused Sacrum totally fused & is fused to ilium Adaptations for fast running w/ narrow gait Includes Dilophosaurus and Coelophysis |
Ceratosaurs
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Non-ceratosaurian theropods
Ancestors to birds in this group Have bird-like features All teeth are in front of orbit Second fenestra opened in front of eye Hind limb modified for speed Expanded distal end of pubis bone |
Tetanurae
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Lightly constructed skull w/ ridge in front of orbit
Rounded rostrum (face) Medially flattened tip of lower jaw |
Allosauridae
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Three groups of Carnosaurs:
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Tyrannosauridae, Allosauridae, and Gorgosaurus
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D-shaped x-section of teeth in premaxillary
Opening in the jugal bone Very small forelimbs w/ 2 functional fingers |
Tyrannosauridae
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Small, long-necked theropods
Evolutionary novelties Extra fenestra in the palate Elongate forelimbs >50% of hind limbs Long slender hand with long second and third digits Arctometatarsalian ankle |
Coelurosaurs
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Coelurosaurs include which groups?
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Ornithomimosaurs
Dromaeosaurs Oviraptorosaurs Troodontids |
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Resemble flightless birds ; no teeth (beak?)
Very lightly built skull w/ very large orbits and shallow snout |
Ornithomimosaurs
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Large head w/lots of serrated teeth
Long forelimbs w/elongate 3 fingered hands Tail w/ ossified tendons Very large claw on digit 2 |
Dromaeosaurs
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Early reptiles vs. Amphibians =
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reptiles = more massive hip girdle, larger hind limb, larger forelimb, stronger vertebral column, more massive shoulder girdle.
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