Studied by 10 people
Carl Linnaeus
Founding father of taxonomy
Introduced a new system for scientifically naming organisms
18th century dude
Taxonomy
The science of naming and organizing organisms into related groups
prior to Linnaeus there was not system which led to considerable confusion regarding classifying organisms
system is still used today
organism is given a binomial name
Binomial Name
Consists of 2 parts 1.Genus name 2. specific epithet
genus name is capitalized, specific epithet is not
the binomial name is always italicized (or underlined if writing by hand) Ex / Homo sapiens /
Can a specific epithet be shared by species who are not closely related?
Yes! As long as the genus is different
the specific combination of genus name and specific epithet are not permitted to be shared by any two species
The Rule of Priority
States that once a species has officially been given a binomial name, the named cannot be changed (unless it turns out that the organism is not really a new species)
How must a biologist officially give a new species a binomial name?
They must publish a description of the new species in a widely distributed and peer-reviewed scientific publication
the published description must contain a list or combination of characteristics that makes the new species unique
Peer-reviewed Scientific Publication
Is one that is not published until it has been reviewed by other scientists to verify that the contents of the publication are legitimate and scientifically reasonable
Holotype
A specimen that is a physical example of the new species
it must be kept at a research institution such as a university or museum such that other scientists may study it
does not necessarily have to be a complete specimen (dinosaur holotypes are hardly ever complete)
in case you were wondering, there is no /Homo sapiens/ holotype. I googled it
Just because 2 organisms look different are they separate species?
No! Individuals may differ morphologically due to intraspecific variation
Interspecific Variation
Individuals that differ in morphology because they be-long to different species
Instraspecfic Variation
Individuals who belong to the same species but have different morphologies Ex Tyler an Austin look different, but still belong to the same species
Four types of Intraspecific Variation
sexual dimorphism
ontogenetic variation
individual variation
taphonomic variation
Sexual Dimorphism
When males and females of the same species look different
Ontogenetic Variation
The variation that you can see between young and old individuals of the same species
Individual Variation
The normal variation that exists among individuals of any given species
Taphonomic Vartiation
Taphonomic process like plastic deformation can change the shape of a bone
Is there a single agreed upon definition of a species
No
The Biological Species Concept
Defines a species as a group of organisms that can successfully interbreed
most common species concept
Where does the biological species concept fall short?
organisms that reproduce asexually
extinct organisms as we cannot observe breeding
Population
Is any grouping of organisms that live in the same geographic area and interbreed
single species are often divided into separate groups by geographic barriers = popualtions
one or more populations make up a species
The Morphological Species Concept
Defines a species as a group of organisms that share a certain degree of physical similarity
this is the definition that paleontologies rely on
Where does the Morphological Species Concept fall short
when faced with intraspecific variation such as
sexual dimorphism
ontogenetic variation
Lumpers
Paleontologists who require more differences before they consider two species to be distinct
Splitters
Paleontologists who require fewer differences before they consider two species to be distinct
Hesperinychus
A dromeaosaurid theropod. The holotype for this species is housed at the University of Alberta
but only the pelvis serves at the holotype
small dinosaur but paleontologists knew it was not a juvenile as the pelvis bones were tightly fused (characteristic of adult bones)
Cryptic Species
Species that look similar but are not cable of interbreeding
Charles Darwin
First to propose the theory of evolution
British naturalist
What did the theory of evolution explain?
how new species came into existence
how organisms adapted to their environment
why specific organism shared certain traits
all life on earth is related and shares a single common origin
Four main principles evolution is based on
Traits are heritable
Variation within a population
Variation of a trait must provide an advantage (differential success) over other variations
Competition --> these four principles lead to change (evolution) over time
Heritable
Means that the trait is part of an organisms genetic code and therefore has the chance to be copied to the organism offspring
Variation
Sometimes an organism has traits that are new and not copied from their parents
potential source = random genetic mutation
Variation Advantage/Differential Success
The variation in a certain trait must provide an advantage for survival for an organism such that there is a better chance that the organism reproduces and passes on that trait to their offspring
Competition
There are limited resources and therefore there is competition for these resources that permits only some organism (the ones who obtain the resources) to successfully reproduce before they die
What happens if a lot of new variations arise/persist in a population?
A new species arises
does not mean the ancestor will go extinct
new species may simply branch off from its ancestor (maybe only a single population was exposed to a new environment that caused the evolution of many new traits)
Is evolution a random process?
No! Even though random mutation may constitute the variation that leads to evolution, the variation will only persist if it posses an advantage in the organisms environment and provides reproductive success(which is not a random process)
Natural Selection
The competitive selective process by which detrimental traits are competitively discarded and advantageous traits are retained
In taxonomy how are organisms group together?
Based on their most recent shared common ancestor
Character
Any heritable trait that can be described and labeled
Shared Derived Character/Synapomorphy
A character that is present in two or more groups and their common ancestor, but is not present in an distantly related groups
What is one of the biggest challenges in determining evolutionary relationships?
Convergent evolution
Convergent Evolution
The evolution of similar traits in two different lineages
usually occurs when two linages must adapt similar environments and similar modes of life Ex the sail in Spinosaurus and Ouranosaurus
Parsimony/Occam's Razor
The simplest answer is usually the right one - always use parsimony when constructing a phylogenetic tree
Node
Where two branched diverge and shows the point at which two lineages share a common ancestor
Clade
A group of organism that share a common node
a clade must contain the ancestor of a group and all its decedents
Does the Linnaean Hierarchy work well with our modern understanding of evolutionary relationships?
No, not really
Thomas Henry Huxley
A close colleague of Darwin and one of the earliest advocates of for the theory of evolution
also the first scientist to recognize that birds evolved from dinosaurs
Archaeopteryx
Specimen that Thomas Henry Huxley designated as the 'miss-ing link" between birds and dinosaurs
Sinosauropteryx
Was the first non-avian (i.e. non-bird) dinosaur to be discov-ered with feathers
specimen in which one of the most significant shared characteristics between dinosaurs and birds was found
Yutyrannus
Largest carnivorous dinosaur found with feathers
Which group of dinosaurs did birds evolve from
Theropods
Are we certain with our definition of what is a bird?
No! There are four contending definitions
Phylogenetic Tree
Diagrams of species organized based on their evolutionary relationships
Scientists take various character traits of species, apply the principle of parsimony, and use a computer program to organize organisms in a sequence of relationships that requires the fewest instances of convergent evolution
composed of nodes and branches
53.Four bird Definitions
Archaeopteryx and all of its descendants
Feathered Dinosaurs
3.Flying Dinosaurs
4.Crown Dinosaurs (the last common ancestor of all extent birds and its decedents)
Problem with Archaeopteryx and all of its descendants Definition
New phylogenetic analysis sometimes show that Archaeopteryx is more closely related to dromaeosaurid than to modern birds
Problem with Feathered Dinosaurs Definition
As more featured dinosaur fossil, like Yutyrannus, are found, more dinosaurs are included in this definition
for example tyrannosaurus would not be considered a bird
Problem with Flying Dinosaurs Definition
It is difficult to determine exactly when dinosaurs were capable of flying (as opposed to simply gliding)
Problem with Crown Dinosaurs Definition
This definition fails to recognize many feathered and flying dinosaurs that are more closely related to modern birds than to Archaeopteryx as birds
however this is the definition favoured by most paleontologists
In sedimentary rocks where are the oldest and youngest rocks?
the oldest rocks are at the bottom
the youngest rocks are at the top
The Principle of Superposition
the tendency for rock layers to be chronolog-ically stacked oldest layers and the bottom and newest layers at the top allows scientists to infer the relative age of rocks layer but not the absolute age
How do Igneous rocks affect stratigraphy?
They may vertically cut through horizontally arranged layers of rocks
How does the building of mountains affect stratigraphy?
They may tilt, fold, or even flip rocks layers
Stratigraphy
The science of using the arrangement and composition of rock layers to interpret geological history
A Formation
A large uninterrupted sequence of rock that is made of multiple layers that all share similar properties (such as mineral composition and average sediment grain size
What does a sequence of rock changing from formation to another indi-cate?
This indicates that a large scale change occurred in the environment where the rocks were being deposited
Isotope
Is a variant of a chemical element that has an unusual number of neutrons
Radiometric Dating
Method to determine the absolute age of rocks
all matter is composed of chemical elements
these chemical elements are atoms composed of a particular number of protons, electrons, and neutrons
some of these chemical elements may exist as isotopes
some isotopes are unstable and will undergo radioactive decay
the time at which some isotopes undergo radioactive decay is a mathematically predictable rate
as rocks age the isotopes decay
using a mass spectrometer it is possible to measure the isotope ratio of a rock and this ratio can tell you how long ago a rock formed
Can sedimentary rock easily be radiometrically dated?
No. They are typi-cally composed of sediments that have already formed and were potentially already undergoing radioactive decay
Can igneous rocks easily be radiometrically dated?
Yes! As they are usually formed a new
How then do we date sedimentary rocks?
By combining radiometric dating and the principle of superposition
What is one of key tools in fossil dating?
Volcanic ash
The Geological Time Scale
A standardized series of chronological devisions that parses the Earth's history into discrete name units
Name the units in the time scale from largest to smallest (4 units)
Eons
Eras
Periods
Epochs
The Hadean Eon
4.6 - 4 BYA
Earth was covered in molten and there was a lot of volcanic activity
young earth collided with a smaller planetoid. This formed a lot of debris that was kept in by earth's gravity and eventually formed the moon
by the end of the Hadean the earth had cooled and large oceans covered much of its surface
complex organic molecules form in the early oceans (may be earth's earliest life forms)
How old are the oldest rocks on earth?
4.4 BYA
rocks discovered on the moon are even older
The Archean Eon
4 - 2.5 BYA
oldest known fossils come from this eon (are simple single-celled organisms)
cyanobacteria evolves (were capable of photosynthesis)
photosynthesis from cyanobacteria produced a lot of oxygen gas that became concentrated in earth's atmosphere
some cyanobacteria formed stromatolites = some of the best records of early life. Look like lumpy stones, but are actually layers of sticky films secreted by cyanobacterial that trapped particles of sediment
The Proterozoic Eon
2.5 BYA - 541 MYA
first multicellular organisms evolve
no bones, so fossil record is poor
later in the Ediacaran period, large life forms with some harder parts evolved (including first animal life)
The Phanerozoic Eon
541 - 0 MYA
split up into 3 eras, Paleozoic, Mesozoic, Cenozoic --> which are subdivided into multiple periods
animal life rapidly evolved into a multitude of diverse forms, including dinosaurs
The Paleozoic Era
541 - 252 MYA
animal life was restricted to primitive invertebrates living in the oceans
also had forest that covered the land, full of reptiles, amphibians, and insects
1/3 eras in the phanerozoic eon
The Cambrian Period
541 - 485 MYA
a period in the Phanerozoic Eon
marks a dramatic diversification of aquatic life = Cambrian Explosion
sponges, molluscs, worms, and many arthropods (including trilobites) evolved
a close relative of vertebrates evolved = Pikaia
Pangea
The continents collided together to form a supercontinent
happened during the Permian period
The Permian Period
299 - 252 MYA
Pangea formed
three major lineages of reptiles evolved
The Mesozoic Era
252 - 66 MYA
often referred to as the Age of the Dinosaurs
dinosaurs evolved during this time and became the dominant form of large terres-trial life
2/3 era in the phanerozoic eon
includes the Triassic, Jurassic, and Cretaceous periods
The Cenozoic Era
66 - 0 MYA
Age of the Mammals
extinction of dinosaurs (except for birds) allowed mammals to evolve larger forms and to fill many of the ecological roles
grass became abundant
3/3 era in the phanerozoic eon
The Triassic Period
252 - 201 MYA
life gradually began to recover from the End Permian mass extinction
first mammals and dinosaurs evolved during the Late Triassic
first ornithischians, theropods and sauropodomorphs appeared (all small and bipedal)
Ichthyosaurs, Plesiosaurs, Pterosaurs, and Rhamphorhynchoids evolved
Ichthyosaurs
evolved during the Triassic Period
name means fish lizard - but they are neither fish nor lizards
ancestors were terrestrial reptiles (found success by returning to water
evolved paddle-like front and hind limbs as well as a finned tail
shark-like dorsal fin
long snout with conical teeth (piscivorous diet)
never evolved gills and had to come to the surface for air
Plesiosaurs
Evolved during the late Triassic Period
are the best ones
large chest and torso
broad-paddle shaped limb
varied tremendously above their shoulders - some had short neck and huge jaws, while other had long necks and small heads
Pterosaurs
Evolved during the Triassic Period
commonly known as pterodactyls
first vertebrates to fly
branched off from the reptilian family tree
have membranous wings supported by a single extremely elongated finger (this differs from birds and bats)
Rhamphorhynchoids
Group of early Pterosaurs
common in the Late Triassic and throughout the Jurassic
The Jurassic Period
201 - 145 MYA
dinosaurs continued to diversify
peak sauropod diversity
small theropods were the dominant terrestrial carnivores
Pterodactyloid group evolved from Rhamphorhynchoids pterosaurs
The Early Cretaceous Period
146 - 100 MYA
dinosaurs continued to diversity
Mosasaurs evolved
Pterodactyloids
Rhamphorhynchoids pterosaurs gave rise to this new pterosaur group
evolved during the Jurassic Period
differed from Rhamphorhynchoids as they has short tails and had carpels in their wrist
had large head crest
were some of the largest animals to ever fly
Mosasaurs
evolved during the early Cretaceous Period
relatives of modern monitor lizards and snakes
had tail fins and limbs modified into paddles
some were very enormous
adapted for deep-sea big-game hunting
The Late Cretaceous
100- 65 MYA
considered the apex of non-avian dinosaur diversity
many famous dinosaurs evolved
at the end of the Cretaceous a large meteor collided with the earth which killed off our nonavian dino buds
What did Alfred Wegener notice?
that the eastern coastline of south Ameri-ca and the western coastline of Africa looked as if they fit together like puzzle pieces
fossils of many ancient animals could be found in both South America and Africa (animals not capable of swimming)
several geological formations in South America had seemingly identical twins in Africa
What did Alfred Wegener suggest based on his observations?
That South America and Africa were once connected and had since drifted apart
however Wegener could not offer a convincing mechanism for how the land masses could move (later on this mechanism was eventually explained)
Crust
The outermost layer of the earth
consist of ocean basins
very thin in comparison to other layers
Mantle
The layer of the earth below the crust
very thick
uppermost part of the mantle is solid and called the lithosphere
The lower part of the mantle is viscous and called the asthenosphere
Lithosphere
The upper portion of the Mantle
composed of many discrete plates that fit together
is solid
Asthenosphere
The lower part of the Mantle
is viscous and slow flowing (but not a liquid) due to the intense heat and pressure (like play-doh)
its shape may be deformed under the uneven weight of the atmosphere
Core
Layer beneath the Mantle
primarily composed of iron and nickel
subdivided into the Outer and Inner Core
Note 
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