Transcript The Fossil Record

Chapter 13 Quiz
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Chapter Quiz on Tuesday, Oct 14th.
Read over notes
Read pages: 268-285
I recommend you do the chapter review questions
Questions to expect:
• Multiple choice
• Short answer
• Maybe a (couple of) long answer question(s)
• Any questions/want some clarifications?
The Fossil Record
Oct. 9th/2014
Mr. Sangra
Learning Outcomes
• How fossils form
• Fossil Evidence
• What the fossil record tells us
How Fossils Form
• Depends on chance
• What are some environments that fossils can be found in?
• In cold places, animals fell in crevasses in ice
• Some were trapped in snow fields
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Some stuck in peat bogs
Quicksand (one of my fears!)
Tar pits
For fossilization, the material surrounding animals helped
preserve them
Rare Fossils
• What is this? What makes this fossil rare? How did it fossilize?
Rare Fossils
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What is this? What makes this fossil rare? How did it fossilize?
It’s an octopus!
Because it’s composed entirely of muscle and skin
When it dies, it quickly decays and liquefies into a slimy blob
or is eaten
• This corpse landed untouched on the sea floor
• The sea floor was free of oxygen, so there were no scavengers
• Both Anoxia (absence of oxygen) and rapid sedimentation rate
prevented decay
• Pushes the origins of modern octopus by
tens of millions of years
Oreodont (hogs) –
Promerycochoerus sp.
• Skull 10 inches long. North American. Resembled You can buy
it for only $1,350.00!
Where are they found?
• Most fossils are found in sedimentary rock.
• How are sedimentary rocks formed?
• When exposed to rain, heat, and cold. This breaks rocks into small
particles of sand, silt, and clay.
• The particles are carried by bodies of water
• Rivers, streams, lakes, seas
• Sink to bottom because they are heavy
• Organisms can become embedded in the sediment layers
• Sediments pile up, pressure on the lower layers compresses
sediments slowly turning them into rock
It’s Sad-imentary
• Preserving fossils depends on luck.
• Sedimentary rocks form in certain bodies of water.
• Organisms in deserts or mountains may never fossilize.
• Many die without leaving a trace.
Fossils
• Paleontologists: scientists who study fossils.
• Fossil record: represents the preserved collective history of
the Earth’s organisms. Not complete, but paints a good
picture.
• The fossil record also tells of major changes that occurred in
Earth’s climate and geography. How?
• Shark teeth found in Arizona indicate there was a great,
ancient sea.
• What happened to the sea?
Laramide Orogeny
What’s next?
• Fossil record activity!
Why didn’t the skeleton go
to the party?
He had no body to go with!
Activity – What you’re going to
do
You’re the world’s top palaeontologist and you’ve just
discovered 7 fossilized skulls of hominids. Your job is to:
1. Sort through the images you’ve collected and match the
similar images together.
2. Describe features of a given specimen as either similar to,
different from or the same as those present in another
specimen.
3. Recognize the sequence pattern in which several human
skull features appeared over time.
Oldest--------------------->Recent
What species is this?
Oldest--------------------->Recent
It’s a chimpanzee!
It is ~ 500,000 – 1 myo
A. africanus
• 3.9 – 2.6 mya in Southern Africa
• Long arms
• Strongly sloping face that juts out from underneath the braincase
• Pronounced Jaw
• It’s pelvis, femur, and foot bones show it walked
bipedally
• Shoulder and hand bones also indicate they were
adapted to climbing
A. boisei
• 2.3 to 1.2 myo
• Eastern Africa (Ethopia, Kenya, Tanzania, Malawi)
• Adapted for heavy chewing
• Strong midline on top of skull anchored the
temporalis muscles (large chewing muscles) from
top of braincase to jaw
• Chewing focussed on molars and premolars
• Flaring cheekbones gave a very wide and dishshaped face creating a larger opening for bigger
jaw muscles to pass through and support massive
cheek teeth that were 4x larger than human teeth
Homo erectus
• 1.89 million and 143,000 years ago
• Northern, Eastern, and Southern Africa
• Western Asia (Dmanisi, Republic of Georgia)
• East Asia (China and Indonesia)
• Oldest known early humans to have had modern
human-like body proportions
• Had long legs and shorter arms compared to size
of torso
this is considered an adaptation to life lived
on the ground
• Lived 9x longer (species timespan) than humans
Homo neanderthalensis
• Also called Neanderthal
• 200,000-28,000 years ago
• Europe and south-western to central Asia
• Our closest extinct human relative
• Large middle part of the face
• Angled cheek bones
• Huge nose for humidifying and warming cold, dry
air
• Shorter and stockier bodies than ours
• Adaptation to living in cold environment
• Larger brains than ours
• Make tools, fires, lived in shelters, made and
wore clothing, skilled hunters
• Buried their dead! No other (earlier) primates did
this
Cro-magnon or
Early Modern Human
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40,000 years ago
Fossils discovered in France hence the name
Thought to be a different species but aren’t
Now called Early Modern Humans
Early humans evolved about 200,000 years ago
Evolved in Africa
Homo sapiens
• 200,000 years ago to present
• Anatomically, modern humans have a lighter
build of their skeletons compared to earlier
humans
• We have very large brains (~1300cc)
• Skull is thin-walled, high vaulted with a flat and
near vertical forehead.
• Much less heavy brow ridges and prognathism
(low jaw)
• Jaw less heavily developed; smaller teeth
• http://humanorigins.si.edu/evidence/human-fossils/species
Hominid Evolutionary Tree
Homo ergaster and
Australopithicus afarensis