Script for
Bones - Present and Past
This slideshow is designed for primary or higher. It is compares skeletal features of different animals and how you can use that to identify different fossils. Note the use of term Charlie refers to a human replica.
Slide 1.
Introduction
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Ask students to describe the images: a mammoth and a human.
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Explain that present-day bones help us to understand past bones (fossils) of
both humans and other animals. Today we are going to look at both modern and
fossil bones.
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Bones and teeth are common vertebrate fossils.
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The
"present is key to the past" is a simple but important statement in
paleontology. Paleontologists look at present day organisms to help
interpret fossils. "Paleo" means old and "onto" means life. Present day
organisms help us to understand the life and environment of past organisms.
Slide 2.
Key Concepts
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Key concepts: Vertebrates make bone
tissue in the present and in the past.
Understanding vertebrate’s skeletal components can help unravel past
vertebrates. Each bone has a
function in making the organisms work.
Slide 3.
Classification of Animalia
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Ask the students if they know what type of animals have bones. The Phylum
Animalia is divided into two groups, the invertebrates and the vertebrates. Ask
if they know how many groups are in the vertebrates? It is five, the fish,
amphibians, reptiles, birds and mammals.
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Go through the different groups of vertebrates and go over some characteristics
of each. Drag the representative of each group into the boxes.
Slide 4. What
is a vertebrate?
Fish
– Reproduce by laying eggs in the water. Can point out one big difference
between a fish skull and a mammal skull is that the fish have their eyes on the
sides of their heads rather than the front of their heads.
Amphibians
– Reproduce by laying eggs in the water, but can go on land as adults. This frog
skull has very large eye sockets, they have large eyes so that they can look out
for predators. Point out the frog’s pelvis. It is much more elongate than
humans. Animals that walk on four legs have a pelvis that is more elongate than
an animal that walks on two legs.
Reptiles
– Reproduce by laying eggs (most) on land. Look at the limbs of the reptile,
they are off the side. This is called a sprawled gait. It is different than
mammals, which have a more upright stance.
Birds
– Birds reproduce by laying eggs on land. Birds have hollow bones; this helps
them to be lighter for flight.
Mammal
– This is what we are. Mammals reproduce by giving live birth on land. Most
mammals have eyes that are on the front of the skull, and most walk on four
legs. Note the length of the horse pelvis.
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Bones protect our organs. Ask which organs are being well protected by the bones
in the image. It is the heart, lungs and liver. Bones also give us structure/a
framework to overcome gravity. Gravity in part makes our bones strong, because
we are always fighting it by being upright.
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Bones make blood. The heart pumps the blood, but it is not made there. Blood is
made by bone marrow. It is a substance that is found in the center of some
bones. Ask if all bones are solid all the way through. Some of our big bones,
like limbs and hips have openings in the center, this is where the marrow is.
The bones themselves also have many small holes. These holes are for blood
vessels to come in and out of the bones.
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Bone store minerals. Bones are made of minerals that combine the elements Ca, P
and O. Ask students how we grow. We get minerals from the food we eat, then our
blood transports those minerals to the bones.
Slide 6. Axial
and Appendicular skeleton
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Can you live if you lose a hand, arm, leg or foot? Yes. These are parts of the
appendicular skeleton; these bones help us to move and we have two sets of them
(i.e. two arms, two legs). These are the
Appendicular Bones.
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Can you live if you are cut in half the long way? No. The bones in the center of
our bodies is the axial skeleton. These bones protect our organs.
These are Axial Bones.
Slide 7.
Composition of bones
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Bones are not uniform all the way through, they have layers of tissue.
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The outer layer is called the periosteum.
It is a membrane that covers the bones and contains blood vessels.
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The compact (cortical) bone tissue, it is very dense and strong. The compact
bone protects our organs and gives the bones strength and structure.
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The spongy bone tissue is in the interior of the bone; it is not nearly as dense
as the compact bone. The spongy bone is filled with bone marrow.
Bone marrow in humans produces 200
billion new red blood cells every day, along with white blood cells and
platelets. It also contains stem
cells.
Slide 8.
Types of Bones
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Long bones – Limb bones
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Short bones – Hand and foot bones
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Sesamoid bones – Knee cap, and small bones in the hands and feet. They protect
the joints and provide smooth surfaces for the muscles to move over.
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Flat bones – Ribs, pelvis, part of the skull
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Irregular bones – Vertebrae (protect nervous system)
Slide 9
– Bones have Names
All the bones have names. Every
species of animals have set number of bones.
As vertebrates grow the number changes.
For examples, an adult human has 206 bones, but a child will have more
until their growth stops. Basic terms include:
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Skull and Mandible – The mandible is the lower jaw bone and often not connected
to the rest of the skull when it is found as a fossil
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Sternum – The sternum is a flat bone in the center of the chest, it connects to
the ribs
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Scapula – These are the shoulder bones. They are flat bones that help us move
our arms
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Humerus – The upper arm bone, it attaches to the scapula with muscles
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Radius and Ulna – lower arm bones. Provide range of motion and together they
provide strength.
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Pelvis – These bones are large. They are bowl shaped in humans (because we walk
upright). The pelvis connects to our sacrum and our legs. Point out the round
area where the femur attaches on the cow pelvis. Often when the pelvis is
fossilized it is in two pieces.
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Femur – Upper leg bone. This is the longest bone in the body
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Tibia and fibula – Lower leg bones. Just like in the arm there are two bones in
the lower limb. Here it provides strength (rather than range of movement).
Here you can also ask how many bones are in the hand. It is 26. How many bones
are in the foot? Also 26. Babies have more bones than adults. Why is this? Bones
fuse together as we age.
Remember, many animals have the same name of bones if they serve the same
function. It is easy to compare and
contrast when you know the human skeleton, from present day vertebrates to past
vertebrate.
Slide 10. Muscles,
Joints and Bones
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How are bones held together? Bones are held together at joints by muscles and
ligaments. We would not be able to move without the muscles, which are attached
to bones.
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Some bones, such as the patella (knee cap) also help to protect the joints.
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Hold up the cow limb bone, point out the bumps/grooves/ridges on the surface.
These are areas where muscled attached. When we look at a fossil we can get an
idea of where the muscles were attached and what they did by looking at these
surface features on the bones. After the pattern of muscles has been determined
by the patterns on the bones, we can then figure out how the skin draped over
the muscles, and whole organisms can be reconstructed just starting with the
groves on bones!
Slide 11.
Arm bone and muscles
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This helps to show how bones and muscles need to work together for our bodies to
move.
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The bicep muscle is on the front of our upper arms, it allows us to move our
lower arm up. Have the students place one hand on their bicep and their arm at
the elbow. They should feel the bicep get shorter. The bicep is using force to
move the lower arm up.
The triceps muscle is on the back of our upper arms, it allows us to move our
lower arm down. Have the students place one hand on their triceps and extend
their arm at the elbow. They should feel the triceps getting shorter. The
triceps is now using force to move the lower arm down.
Slide
12.
Bones and Joints
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Notice the movement of the joints. There are three joints moving, hip-upper leg,
upper leg-lower leg, lower-leg foot.
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Many different muscles are working with these bones to allow all of these joints
to move.
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There are some joints that humans do not have that four-legged animals have,
such as those in the tail bone. Point out Charlie’s sacrum and coccyx and hold
up the cow sacrum. The cow sacrum is very big and deep. It needs to be very big
because muscles from the tail attach to it. We have a smaller sacrum and a very
small coccyx (tail bone) because we do not have a tail.
Slide 13.
Age of Bones
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Our bones change as we age. When we are babies we have more bones, that begin to
fuse as we grow.
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As we grow, bone is added to shafts of the bones, when we stop growing the shaft
of the bone fuses to the end of the bone (the portion near the joint).
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Compare mammoth with human femur and locate the head
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The photo of the femur head of Columbian mammoth is a young mammoth whose head
did not fuse to the rest of femur.
One of the ways you an tell the age of bone when it died.
Slide 14.
Horse Bones
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Leg bones of horses include cannon bones, the metacarpals and phalanx are part
of leg (look at picture to left for more information.
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Horses are ungulates so they have a hoof
(or modified toe nail)
Slide 15.
Columbian Mammoth Bones
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Toe nails rather than hooves
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Skeleton similar to elephant
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The Columbian mammoth is an extinct species of mammoth that inhabited North
America as far north as the northern United States and as far south as Costa
Rica during the Pleistocene epoch. It was one of the last in a line of mammoth
species, beginning with Mammuthus
subplanifrons in the early Pliocene
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Tusk up to 13 feet in length, larger than the wooly mammoth which lived in
cooler climates
Slide 16.
Tyrannosaurs Dinosaur Bones
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Arms were distinct from feet. Look
at picture that compares human with T. rex arm.
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Pelvis helps to determine type of dinosaur
Slide 17. Fossilization
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First an organism has to die. All the “gooey” soft stuff will be eaten away
either by animals or bacteria, and a hard part will remain. It is then buried.
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The fossil is then exposed either by erosion or someone excavating the site.
Notice that fish (a vertebrate) can be
identified but if you look at the snail shell, it had a hermit crab inside.
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Fossils help paleontologists tell a story, but sometimes the clues do not tell
the entire story.
Slide 18.
Information from fossil bones
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Bones can tell a story. Each
individual bone can tell you what part of the animal and many times can lead to
identification of the animal. It
also may tell you how and where it got buried, including if it was eaten or its
owner died of a natural death.
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Just one piece of bone can allow a paleontologist to dream of what might have
been
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Fossils can provide more information than just the name of an organism. It can
tell you how the organism became a fossil. When a land organism dies, its body
is usually picked over by other animals and bones are scattered around. The
bones can be eroded by different weather conditions.
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A dinosaur grave site is like a crime scene. The paleontologist tries to
interpret how the organism’s remains came to this area. This is called the study
of taphonomy. Paleontologists can determine if the bones were transported
or whether the organism died at that site. Finding an entire skeleton of a land
organism is rare, especially the large dinosaurs and mammals.
Slide 19. Stegosaurus
Gravesite
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This is because on land fossils do not get buried as fast, so they are exposed
to scavengers and the elements.
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Often the bones get spread out and only fragments remain. It can be hard to tell
what the animal was by the fossil fragments.
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Difficult to determine if organism is extinct and nothing to compare with
Slide 20.
Mammoth
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Mammoth were similar to elephants.
They had six sets of teeth, and around age 60 they lost their teeth and could
not eat the 800 pounds it would take.
They usually went to a river to live out its life and then get buried
within the sediments of the river.
· There is also examples of mammoth that fell into limestone sink holes and got buried in Hot Springs, South Dakota
Slide 21.
Dreaming of Bones
Remember some of these bones might have been someone’s dinner!
Let’s go look for bones.