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Notes on video lecture:
The Origin of Vertebrates
Notes taken by Edward Tanguay on October 25, 2016 (go to class or lectures)
Choose from these words to fill the blanks below:
homology, lobster, endostyle, pharyngeal, clade, evolutionary, analogous, belly, synapomorphy, anus, indoskeleton, diversity, cilia, notochord, philogenetic, vertebral, oxygen, backbone, Cambrian, wings, metabolism, arm, kangaroos, lampry, metacarpals, terrestrial, narrow, dorsal, wings, pathways
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origin of vertebrates
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525 million years ago during the                  explosion
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saw the rise in organism                   
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humans, other mammals, reptiles, birds, amphibians, and fish are all part of a large            of animals called the vertebrata, or vertebrates
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vertebrates are part of a larger clade called the Chordata
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animals that have a stiff chord in their back
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a sea squirt is more closely related to humans than a clam, a jellyfish or a               
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attach themselves to a spot on the sea floor and filter food particles out of the water around them
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yet juvenile or larval sea squirts can swim freely or float in the water
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have a structure called a                   , a stiff but flexible rod made out of fibers of a material called collagen
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notochord is a useful thing to have because it provides an anchoring point for muscles to attach to and pull against
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the notochord is the beginning of the vertebrale                         
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this is different than the hard exoskeletons found in invertebrates like crabs, spiders and insects
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eventually the notochord was structurally replaced by the vertebrae of your                 
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but even you had a notochord for a little while when you were a developing embryo
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above the notochord is another one of the important features found only in chordates
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the hollow              nerve chord
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some animals like earthworms and insects have a nerve chord that is solid and located ventrally in the animal
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so it runs along the           
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but chordates have a nerve that run along our back dorsally
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it is hollow and sits above the notochord
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in humans it is enclosed by the vertebrae of our backbone
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called the vertebral column, or the spinal
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a shared ancestory between two or more different features or traits in different organisms
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a charactertistic shared by some members of a larger group, a shared derived character
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humans and birds are both vertebrates
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we inherited our skeletons from a common vertebrate ancestor
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our skeleton is homologous with that of a bird
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humans and                    are also part of a smaller group called mammals
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we share fur with kangaroos which birds don't
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convergent characteristics
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appear similar but arose separately
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results in analogous traits
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similar due to a shared function
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insects and birds both have           , but they didn't inherit their wings from a winged, common ancestor
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so insect and bird wings are                    traits
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wings of birds, bats and terrasaurs
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if we look at these animals on a simplified,                          tree
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the last ancestor these animals shared was a primitive, terrestrial tetrapod with walking limbs
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these animals didn't inherit their wings from a single, common, winged ancestor
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the wings evolved independently in this distantly related lineages
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therefore these are convergent, or analogous features
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but take a look at their        bones
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they all have the same limb bones
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a humorous, radius, carpals,                       , and phalanges
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they are arranged in the same way even though the shape of the bones are different
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the bones of the similar because they inherited them from their common ancestor
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the same feature can be homologous at one level, and analogous at another
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these features are homologous as           , and analogous as limbs
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our chordate relatives
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the notochord and the dorsal hollow nerve cord
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features found in all chordates
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therefore homologous characters within vertebrates
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in humans, the notochord is no longer present
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has been functionally replaces by our                    column
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if you were to cut a larval sea squirt in half
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you would see a series of              openings
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these are                      slits, which become the gill openings in fishes
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fishes like the shark have gills used for respiration, transferring              into the bloodstream
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sea squirts use their pharyngeal slits for eating, they bring water into the pharynx and filter food out of it
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pharyngeal slits are one of the characteristic features of chordates
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                       chordates lost their gills
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if you look at a human embryo, you'll see the beginnings of the pharyngeal slits for a little while during development
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a long groove on teh bottom side of the pharynx
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foudn in sea squirts and some larval vertebrates like the             
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the endostyle is lined witih tiny hair-like structures called           
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these spread a coating fo mucus that is secreted by cells which traps food particles
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the endostyle is homologous with our thyroid gland
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our thyroid gland regulates our                     
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in many animals, the digestive system ends in the          which is at the end of their body
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chordates have a post-anal tail
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so we share with chordates the fact that our bodies continue beyond the end of the digestive tract
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humans don't have tails when we are born, but we do have tails when we are embryos
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sea squirts and humans look very different
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took very different evolutionary                 
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but we still have some features in common during our early embryonic development
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those shared features show our shared                          history as chordate animals

Vocabulary:

clade, n. From the Greek κλάδος ("branch"), a group of organisms that consists of a common ancestor and all its lineal descendants. Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. ⇒ "Humans, other mammals, reptiles, birds, amphibians, and fish are all part of a large clade of animals called the vertebrata, or vertebrates."
homology, n. From the Greek ὁμός ("same") and λόγος ("relation"), the existence of shared ancestry between a pair of structures, or genes, in different taxa, a shared ancestory between two or more different features or traits in different organisms. ⇒ ""A common example of homologous structures in evolutionary biology are the wings of bats and the arms of primates.""

Spelling Corrections:

primative ⇒ primitive

Ideas and Concepts:

Getting to know our earliest ancestors, via tonight's Vertebrate Origins class:

"Vertebrates are part of a larger clade called the chordata, animals that have a stiff chord in their back. A tunicate, or sea squirt, belonging to the chordata clade, is therefore more closely related to humans than clams, jellyfish, or lobsters.

While adult tunicates attach themselves to a spot on the sea floor and filter food particles out of the water around them, juvenile or larval tunicates can swim freely or float in the water. The reason they are able to do this is that they possess a structure called a notochord, a stiff but flexible rod made out of fibers of a material called collogen.

A notochord is a useful structure to have because it provides an anchoring point for muscles to attach to and pull against. The notochord is the beginning of the vertebral endoskeleton and is thus different than the hard exoskeletons found in invertebrates like crabs, spiders and insects.

Eventually the notochord was structurally replaced by the vertebrae of your backbone, and even you had a notochord for a little while when you were a developing embryo."
The Origin of Vertebrates
Vertebrate Environments
Diversity of Early Vertebrate Life