Work Sample

How Big Was the Skull?

The Find• I found a ground sloth

tooth in Wilsonville, Oregon

• No other fossil material was located in that area

• It measures 22.70mm x 13.85mm

• The tooth is the third left tooth of a cranium from a Megatheriium ground sloth

http://www.fossil-treasures-of-florida.com/harlans-ground-sloth.html for the color photo of the toothB. J. Shaw: American Museum of Natural History specimen

Question

• Can I determine the size of the skull based on a single tooth?

• How could I do that?

http://apod.nasa.gov/apod/image/0507/impact13sec_deepimpact_hri.jpg

Hypothesis

• Develop a hypothesis about the outcome of your experiment based on your observations, reading, and experience

B. J. Shaw, American Museum of Natural History

Experimental Design

• Let’s figure this out together

• We need a plan• We need a data sheet• How will you analyze

these data?• Do we need to modify

our hypothesis?

B. J. Shaw, American Museum of Natural History

Collect Data

• You need to use calipers for taking precise measurements

• How to read a Vernier Scale (in mm)

Practice

• What is this measurement?

Practice

• What is this measurement?

• 8.65mm

http://www.southalabama.edu/physics/lab_setup/ph114_201/caliper%20(Small).jpg

Analyze Your Data

• Your data sheet should be an organized table for collecting the measurements

Analyze Your Data

• We discussed different ways of analyzing these data as part of our experimental design

• Is that still a good approach?– Does this make sense?

Skull Comparisons

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Species

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Analyze Your Data

• How about a scatterplot, using an estimated least-squares line?– For those of you

working with 8th graders or advanced math students, you can have them calculate it

• Any other ideas for graphing?

Nine-Banded Armadillo Skulls

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Tooth Length in mmS

kull

Len

gth

in

mm

Conclusions

• Was your guess correct?

• What is the estimated skull length?

• If you have any unusual data, give an education guess what happened (most likely, human error)

Nine-Banded Armadillo Skulls

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0 5 10 15 20 25 30 35 40 45

Tooth Length in mmS

kull

Len

gth

in

mm

For This Lab…

• Produce an 8½ x 11” or larger “poster” of this experiment

• Introduction: Background on allometry and Xenarthrans

• List your citations

• Methods: Describe your experimental design (include your hypothesis)

• Results: Include a graph of your data

• Discussion: Was your prediction correct and what did you learn

Be Creative

Have Fun

What Did You Learn?

Include 5 Sections