Stratigraphy and geologic Time Flashcards
true or false - the oldest rocks are found at the bottom
true
the tendency for rock layers to be chronologically stacked is called …
principle of superposition
how do people interpret geological history
stratigraphy - science of using the arrangement and composition of rock layers
define a formation
a large uninterrupted sequence of rock that is made of multiple layers and share similar properties and conditions
what does it tell us when a rock changes from one formation change to another
indicates that a large scale changed occurred in the environment where the rocks were being deposited
true or false - we cannot tell the relative age of the rock from the principle of superposition
false - we can, but we cannot tell the absolute age
how do we find the absolute age of the rocks
radiometric dating
an _____ is an element that has an unusual number of neutrons
isotope
true or false - all isotopes are stable
false - some are unstable and undergo radioactive decay
when a new rock forms, what happens to the ratio of isotopes and decay products
ratio matches that of the environment
when a rock ages, what happens to the ratio of isotopes and decay products
the ratio decreases
how can we measure the isotope ratio of a rock
mass spectrometer
what does the ratio of isotope to decay products tell us
how long ago the rock formed
true or false - sedimentary rocks are never “new”
true
true or false - sedimentary rocks can be radiometrically dated
false - igneous rocks can be
with sedimentary rocks, how can we tell how old the rock layer/fossil is
combining radiometric dating and principle of superposition
true or false - lake deposits are a key took in fossil dating
false - volcanic ash deposits are
define the geologic time scale
a standardized series of chronological divisions that parses the Earth’s history into discrete named units
the largest units in the time scale are
a) eras
b) periods
c) eons
c
describe the Hadean eon
- named after Hades, the greek god of the underworld
- rest of the universe was over 9 billion years old
- surface of the earth was partially molten and volcanic activity widespread
- earth collided with a small planet -> ejection of large mass of debris -> formed the moon
- possibly created the earliest true life forms
- rocks on the moon are older than the rocks on earth
which eon did the oldest fossils come from
a) mezezoic
b) hadean
c) archaen
c
describe the fossils that can be found in the Archaen era
- fossils are simple single celled organisms
- cyanobacteria (advanced form) -> photosynthetic, produced lots of oxygen gas -> also formed stromatolites
true or false - stromatolites are the best records of early life
true
how are the layers in the cyanobacteria created
by the secretion of sticky films that trapped particles of sedimentary
which eon did the first multicellular organisms evolved
proterozoic eon
true or false - proterozoic eon has the best fossil record of early life
false - it is quite poor
what is the name of the time span between 630 and 540 million years ago, found in the proterozoic eon
Ediacaran period
when did the first animal life come about
the ediacaran period
which eon is subdivided into three eras
the phanerozoic eon
when did dinosaurs evolve
phanerozoic eon
describe the paleozoic era
at the beginning, animal life was restricted to primitive invertebrates in oceans
What is the geologic name for the Age of Dinosaurs?
mesozoic
When was the mesozoic era?
252 to 66 million years ago
which oraganism lived during this mesozoic?
- marine reptiles: ichthyosaurs, plesiosaurs, mososaurs
- first true turtles
- crocodilians
- lizards
- snakes
- mammals
- birds
- first flowering plants
geologic name for Age of Mammals? when was it?
Cenozoic Era - 66 to 0 million years ago
Since which geologic period have mammals been around?
triassic
in which era do grasses become abundant?
cenozoic
In which geologic period do global temperatures begin to cool? When was this period?
paleogene - 66 to 23 million years ago
in the paleogene period, what forms did the mammals diversify into?
primates, bats, whales
In which period did gobal temperatures continue to cool and the first hominids evolved in Africa? When was this?
neogene - 23 to 2.6 million years ago
In which period did the earth experience several large glaciation events, the first modern human evolved, and human civilization spread? When was this?
quaternary - 2.6 to 0 million years ago
for how long did the non-avian dinosaurs exist?
135 million years
TRUE or FALSE: there is less time separating the first humans from the last dinosaurs than there is separating the last dinosaurs from the first dinosaurs (i.e. first humans closer to last dinosaurs)
TRUE
When was the triassic period?
252 to 201 million years ago
During which period did pangaea begin to break apart?
triassic
When did the first mammals and dinosaurs evolve?
late triassic
TRUE or FALSE: during the triassic, ornithischians, theropods, and sauropodomorphs were all mostly small and quadrupedal.
FALSE: small and BIPEDAL
what was the first large herbivorous dinosaur? What is its dinosaur classification?
plateosaurus (prosauropod)
When did the ichthyosaurs first evolve? What does ichthyosaur mean - why is this strange? Were their ancestors marine or terrestrial reptiles?
- triassic
- “fish lizard”, but neither a fish not a lizard; named this way because they are reptiles that took on a fish-like lifestyle and evolved fishy body form
- ancestors were terrestrial reptiles
To adapt to an aquatic life, ichthyosaurs evolved: (select all that apply)
a) paddle-like front limbs
b) paddle like hind limbs
c) finned tail
d) gills
e) shark-like dorsal fin
f) large chests and torsos
g) short tails
h) conical teeth
i) long snouts
j) piscivorous diet
a) paddle-like front limbs
b) paddle like hind limbs
c) finned tail
e) shark-like dorsal fin
h) conical teeth
i) long snouts
j) piscivorous diet
Which marine reptile group joined the ichthyosaurs in the late triassic? What is an example of this dinosaur?
plesiosaurs - e.g. elasmosaurus
To adapt to an aquatic life, plesiosaurs evolved: (select all that apply)
a) paddle-like front limbs
b) paddle like hind limbs
c) finned tail
d) gills
e) shark-like dorsal fin
f) large chests and torsos
g) short tails
h) conical teeth
i) long snouts
j) piscivorous diet
a) paddle-like front limbs
b) paddle like hind limbs
f) large chests and torsos
g) short tails
What were the first vertebrates to fly? When did they evolve? describe their wings. What early group do they belong to?
- pterosaurs
- triassic (Same time as dinosaurs)
- membranous wings supported by a single long finger
- early group: rhamphorhyncoids
Which period marked the peak of sauropod diversity? When was it?
jurassic - 201 to 145 million years ago
Which period are stegosaurs almost completely restricted to?
jurassic
when did the first ankylosaurs, ornithopods, and ceratopsians first appear
jurassic
when did the first birds, including Archaeopteryx, evolve?
jurassic
What are the most famous records of dinosaurs from teh jurassic?
- morrison formation of western USA
- solnhofen limestone of Germany
what new pterosaur group arose in the jurassic? How are they different from the rhamphorhynchoids? What is an example of a dinosaur from this group?
- pterodatyloids - e.g. pteranodon
- short tails, carpals in wrists, larger wingspan, large head crests
TRUE or FALSE: pterodactyls are the largest animals to ever fly
FALSE: pterodactyloids
What are some sauropods found at the morrison formation?
diplodocus, brachiosaurus, camarasaurus
When did the first flowering plants evolve? When was this?
early cretaceous - 146 to 100 million years ago
Which new theropods evolved in the early cretaceous?
spinosaurids, carcharodontosaurids
what are the most famous records of dinosaurs from the early cretaceous?
- yixian formation of China
- wealden supergroup of England
- cedar mountain formation of Utah
What are the 3 major reptilian groups of the Mesozoic? Which one evolved in the early cretaceous?
- ichthyosaurs, plesiosaurs, mosasaurs
- mosasaurs evolved in early cretaceous
mosasaurs evolved: (select all that apply)
a) paddle-like front limbs
b) paddle like hind limbs
c) finned tail
d) gills
e) shark-like dorsal fin
f) large chests and torsos
g) short tails
h) conical teeth
i) long snouts
j) piscivorous diet
k) long tails
l) long bodies
m) carnivorous diet
a) paddle-like front limbs
b) paddle like hind limbs
c) finned tail
j) piscivorous diet
k) long tails
l) long bodies
m) carnivorous diet
Describe the Wealden scene.
theropod Neovenator attacks a pair of Iguanodon, while the small heterodontosaurid Echinodon flees; the early ankylosaur Polacantus is well protected by its armour
Which period was considered the apex of non-avian dinosaur diversity? when was it?
late cretaceous - 100 to 65 million years ago
What are some of the main coelurosaurian theropods from the late cretaceous?
- tyrannosaurs
- ornithomimids
- therizinosaurs
- oviraptorosaurs
- dromaesaurids
- troodontids
What are the 2 groups of anklosaurs? When did ankylosaurs diverge into these 2 groups?
- tail-clubbed = akylosaurids
- clubless = nodosaurids
- late cretaceous
What are the dominant large herbivores in the northern hemisphere during the late cretaceous?
ceratopsians and hadrosaurs
What are the dominant herbivores in the southern hemisphere during the late cretaceous?
titanosaurid sauropods
Which other dinosaur group with hard dome shaped heads is from the late cretaceous?
pachycephalosaurs
what is the significant event that occurred during the Cambrian period
the dramatic diversification of aquatic animal life referred to as the Cambrian explosion
what are some examples of animals that evolved in the Cambrian period
sponges, worms, molluscs and arthropods
___ is a close early relative of vertebrates but didnt have a vertebrae
Pikaia
what is the name and group it belonged to of the top invertebrate in the Cambrian oceans
invertebrate Anomalocaris
_____ has a bizarre Cambrian characteristic and remains a mystery in terms of its habits and relationships
Opabinia
true or false - Pikaia had a hard skeleton
false
when did fish become the dominant large aquatic animals
Ordovician period
true or false - the sea levels were very low during the Ordovician period
false - they were very high
in the Silaurian period, there came the evolution of
a) jaws in fish
b) gills in fish
c) large land predators
a
with the evolution of fish with jaws, came the evolution of ____
predatory fish
the _____ are a group of early jawless vertebrates
a) Pikaia
b) Osteotracans
b) Opabina
b
when did Dunkleosteus and Tiktaalik evolve
Devonion period
what kind of fish are Dunkleosteus and Tiktaalik
tetrapods
true or false - the Dunkleosteus had huge jaws
true
describe the Carboniferous Period
- many amphibians
- first amniotes evolved
- the rotting plants from this period -> formed coal
name the single super continent
Pangea
when did Pangea form
the Permian Period
what did each of the lineages of reptiles evolve into
anapsids
diapsids
synapsids
anapsids -> turtles
synapsids -> mammals
diapsids -> snakes, crocodiles, dinosaurs
true or false - we were diapsids before mammals
false - we were synapsids
describe the environment of the Permian period
dry and desert
when did the single greatest mass extinction occur and of what
Permian period - loss of trilobites
