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Notes on video lecture:
Vertebrate Environments
Choose from these words to fill the blanks below:
scraped, sources, scavenge, 150, anoxic, geology, brackish, inhabited, saltier, beaches, photic, shoal, pelagic, ripples, land, mollusks, chert, reefs, sediments, less, fossils, plankton, shallow, exquisite, features, shales, sinks, 200, flatter, layers, continental, slopes, marine, mud, tidal, carbonate, light, Cambrian
what kinds of environments the earliest vertebrates                   
paleontology is blending of
biology
              
to understand how and why certain                  evolved, we need to interpret the rocks that fossils are found in
this tells us what kinds of environments the animals lived in
depositional environments on          are more common
depositional environments in the ocean are less common
since life began in the oceans, we need to understand this habitat and its depositional environments
most common place to find fossils of              organisms like fish, corals, crustaceans, or clams
the continental shelf
in the                waters off the coasts of continents
               are high energy environments
delicate fossils can be broken and eroded
continental              and the deep ocean are hard for us to reach
how to tell what the environment was like when the fossil animals were alive
geologists interpret rocks in two ways
what the rock is made of
what kind of sedimentary structures were preserved when the rock was deposited
there are also fossils in                    rocks
made up of at least 50% calcium carbonate
mostly limestone
limestone is made up of the shells of marine animals such as                 
key fossil localities
rivers
most energetic near their                in highlands
most rivers transport and deposit sand and mud
some with strong currents move gravel
lens shaped sand or gravel channel deposits are an indicator of a fluvial environment
as rivers travel over gradually                land, change to meandering rivers with shallower, wider channels
able to transport          material
rivers end up at an ocean, sea, or large lake
empties into sea at a delta or an estuary
here you find carbonate sediments
water here is                 , i.e. not as salty as ocean water
some animals and plants are adapted to live in this type of water
heavily influenced by actions of the tidal current which produces sedimentary structures
herringbone cross-stratification
alternating parallel             
this means the sediments were probably deposited in a            environment
horizontal beds are called cross beds
inclined layers are cross-strata
sediment was being deposited fast in order to preserve the cross-stratification
waves also affect cross-stratificaton
wave base
deeper during storms
shallower during fair weather
many fossil localities were deposited below storm wave base
usually have             
rocks with the most                are from the shallowest environment
barrier islands
spits
small point of land running into the sea, or a long, narrow            extending from the shore into the sea
lagoons
areas of quiet, low-energy water
fine sediments can be deposited here
water evaporates and concentrates minerals
can become                than ocean water
forms evaporate
calcite
calcium carbonate
gypsum
anhydrite
calcium sulfate
halite
sodium chloride
usually what we mean when we say salt
interbedded with       
if we find these minerals, there is a good chance we are looking at what used to be a shallow lagoon
good environments for preserving               
because the water is still
are still and salty
not a lot of things can live in them
becomes             , i.e. little oxygen
this means if an animal falls into the lagoon and sinks to the bottom, there aren't many animals living their to                  the carcass
small grain size tells us that the waters were very still
good for preserving details
here we find some of the most                    fossils every found have come from lagoon or lagoon-like environments
Archaeopteryx
deeper continental shelf environments
Man on the Hill
preserves 415 million year old vertebrate fossils
accumulated in deep water on the continental shelf
the environment was close enough to land for fine                    to be deposited
but far enough offshore that most of the sedimentation was carbonate
ripples became less common
carbonate platforms
where you find marine fossils
the              zone
where            penetrates
a few centimeters to        meters deep, depending on the clarity of the water
plankton
float and form the basis of the marine food chain
here we find           
corals thrive in nutrient-rich water
the steeper the slope, the less stable
plate corals
make the most use of the least light
in deeper waters, chances of finding vertebrate fossils becomes relatively small
turbidites
deposits that can form in many environments
occur in deep water
Burgess Shale
most famous                  fossil locality area in the world
famous for the exceptional preservation of the soft parts of its fossils
likely deposited by a turbidity current
ocean floor
here we don't find many vertebrates
find mostly skeletons of                 
these animals are               
spend their lives floating in the water column
          
fine-grained silica-rich microcrystalline or cryptocrystalline sedimentary rock that may contain small fossils
most of the sea floor in earth's history has been melted and recycled into new crust, taking its fossils with it
the old ocean crust still in today's ocean is about        million years old
not that old compared to the oldest                        rocks
over 4 billion years old
when an oceanic plate means a continental plate, the oceanic plate           
the oceanic crust is subducted beneath the continental crust
most marine fossils come from continental shelf deposits
when oceanic plates meat a continental plate, some contents get                off

Ideas and Concepts:

Our best fossils and the geological localities which produced them, via tonight's Vertebrate Origins class:

"The Archaeopteryx [German:Urvogel, "original bird"], [Greek:ἀρχαῖος (ancient) πτέρυξ (feather)], is a genus of bird-like dinosaurs that is transitional between non-avian feathered dinosaurs and modern birds. It lived in the Late Jurassic around 150 million years ago, in what is now southern Germany during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now.

Over the years, twelve body fossil specimens of Archaeopteryx and a feather that may belong to it have been found. All of the fossils come from the limestone deposits, quarried for centuries, near Solnhofen, Germany. The initial discovery, a single feather, was unearthed in 1860 or 1861 and described in 1861 by Hermann von Meyer. It is currently located at the Humboldt Museum für Naturkunde in Berlin. The first skeleton, known as the London Specimen was unearthed in 1861 near Langenaltheim, Germany.

The reason we have these exquisite fossils of the Archaeopteryx is because they lived near lagoons, or areas of quiet, low-energy water. These are areas were fine sediments are deposited, where water evaporates and concentrates minerals, and thus becomes saltier than ocean water.

Since this leads to a waters with a high-salt concentration, it becomes anoxic, i.e. has little oxygen, and thus not many animals can live here. This means if an animal falls into the lagoon and sinks to the bottom, there aren't many animals living there to scavenge the carcass. Also, the small grain size tells us that the waters were very still and thus good for preserving details. This is why some of the most exquisite fossils every found, such as the Archaeopteryx, have come from lagoon or lagoon-like environments."
The Origin of Vertebrates
Vertebrate Environments