Evolution of Hominini ~ Part Two

This entry starts here at Evolution of Hominini ~ Part One

We spent a week taking measurements of our Smithsonian ancient human skull models, and recording our measurements. We graphed them and drew what we saw so that we could compare some things...

From most recent to earliest species, here is our documentation:

Homo sapiens- the largest braincase, smallest snasal opening and teeth

Homo heidelbergensis - a predecessor to Neanderthal. He's got a big nasal opening!

Homo erectus ~ not a bad looking species!

Homo rudolphensis ~ brain case is much smaller than more recent species!

Australopithecus africanus ~ a tiny brain case (but still larger than many mammals!) and
a huge jaw

Graphing out and comparing the nasal opening

More graphing of the width of the face and size of the jaw

Graphing out the size of the teeth. When you compare Taung Child's teeth (A. africanus) to
Homo sapiens' (us) teeth, it's remarkable. Taung had a tiny brain and huge teeth. We are the
opposite.

Here's everyone lined up so you can compare. Clearly, the earliest hominin has the smallest brain and largest jaw. Over time,
brains get larger and jaws and teeth get smaller. 

Devonian Gorge, Iowa City

In the early weeks of April, we trekked up to Iowa City to the big MAPS Rock and Fossil Sale in Iowa City. It's the largest gathering in the Midwest, and we try to go every other year.

While in the neighborhood, we take a 20 minute detour to the Devonian Gorge, an amazing area where fossils can be found. The site is protected, and collecting is prohibited.

In 1993, a flood breached the dam wall above the gorge, and washed out what was just grassy camping and picnicking area. The flood was such a gusher that it removed ALL of the soil down to bedrock. This event exposed a treasure of fossils embedded in the bedrock, all from Devonian times.

Now you can walk the gorge (it's not very large and the walk is well under a mile on easy, even surfaces) and see geological features marked along the way.

We just love going there and each time we visit, we apply a new layer of geological knowledge to what we see. I'll never get tired of visiting!

The Evolution of Hominini ~ Part One

This is part one of a two part blog entry. Please see The Evolution of Hominini ~ Part Two here!

As part of my Big History class with a local homeschool co-op, I taught a class about hominini (hominins, or what we used to call hominids) from Australopithecus to Homo sapiens. In case you are curious about the usage of hominin vs. hominid, here is a great explanation!

The class was great fun, and we were very fortunate to have a particular educational resource from The Smithsonian Human Origins program. Last year, The Smithsonian exhibit visited our public library and left a gift of laser printed hominin skulls to be used for education. I checked the skulls out and ....well, it was a gleeful time! Only other anthropology geeks will understand why this is so exciting! :D

Using the wonderful DK book,  Evolution: the Human Story to show the kids what the hominins might have looked like!

I only have one hour with my homeschool co-op class, so sometimes it feels like I'm crunching a lot into a short time. As it was, the kids were able to take measurements of the skulls and draw conclusions from those measurements by comparing them.

Some basic trends are that hominin skulls (the cranium) get larger over time. The jaw and teeth get smaller. The foramen magnum (hole where spine goes into the skull) moves from back to center bottom. The nasal openings get smaller, and jaws move under the skull as the frontal cortex becomes larger. We know about these trends, but when you actually measure the skulls of hominins through time, you can see the trends as well as feel them with your hands! This is why I love hands on work. 

A skunk skull (modern), Australopithecus skull, and modern Homo sapiens skull. Compare the position of the foramen mangum (where the brain stem exits the skull). In the skunk, it is located toward the back of the skull, as its head is thrust forward like a typical quadruped. The Australopithecus (Taung Child) foramen is moving below, and by the time we get to modern humans (and in fact well before) the foramen is centered directly under the skull. This is the trait of upright walkers or bipedal hominins!

We used calipers to measure the skulls. As always, being on a budget means I'm creative. I found a template for making cardboard (or cereal box) calipers that worked wonderfully. And then the kids got to keep their calipers since they were so easy to make and were plenty.

Here is a link for the cardboard calipers. These work great!

I used the wonderful DK Publishers book, Evolution ~ the Human Story, to show the kids what each hominin might have looked like in real life. It's so hard to understand when looking at bones. The eyes and delightful expressions in the models' photos really bring them to life, and tap into the kids' interest. 

Australopithecus compared to a modern Homo sapiens. The jaw (upper maxilla) becomes much smaller over time, and retreats under the enlarging frontal cortex (forehead). You can see how the brow ridge shrinks and also retreats under the frontal cortex, and how much larger the cranium becomes. Just a few million years of evolution...

These are the lovely Smithsonian Human Origins skulls that I was able to check out from the library. They are laser printed, although they are very nice and accurate models. Each one is a near replica of its real fossil.
From left to right: Australopithecus africanus (Taung Child), Homo rudolphensis (similar to H habilus or 'Handy Man'), Homo erectus (one of whom is known as 'Java Man' and is related to H. ergaster or 'Turkana Boy"), Homo heidelbergensis (Heidelberg Man) who is a predecessor to Neanderthal, and finally a modern Homo sapiens (this one is Fish Hoek).
Seriously, I can't get over what an amazing resource these skulls are!

We are still all unfolding in this universe! And feeling a bit silly.

In the next post, I will show more information about each hominin skull, how we charted the measurements, and what we concluded from them.

Here is a nice list of what to measure and what to look for on each skull.

Link For Indiana.edu skull measurements 

© 1999 ENSI (Evolution & the Nature of Science Institutes) www.indiana.edu/~ensiweb

This material may be copied only for noncommercial classroom teaching purposes, and only if this source is clearly cited.

HOMINID CRANIUM COMPARISON CHECKLIST
Martin Nickels

PLEASE READ THESE 5 STATEMENTS BEFORE BEGINNING THIS ACTIVITY:

1. Work in groups of 3-4 students so that everyone can be involved in the activity.

2. BE SURE (!) TO TAKE TURNS doing different measurements and observations.

3. When taking a measurement, use the SLIDING CALIPERS (except for #11 & #12 which may require the HINGE calipers) and remember to...

4. ALWAYS MEASURE IN MILLIMETERS [mm] and round off to whole numbers.

5. PLEASE DO NOT ADD ANY PENCIL OR PEN MARK "TATTOOS" TO THESE CRANIA, OR STICK YOUR FINGERS IN THEIR EYE ORBITS OR NOSES!

-----------------------------------------------------------

I. BRAINCASE: (7 items #1-7)

1. Does the FOREHEAD (frontal bone) look more vertical OR flatter when the skull is held in normal anatomical position [NAP] (i.e., with the eyes oriented forward)?

2. Is a SUPRAORBITAL BROWRIDGE present?

3. If present, is the BROWRIDGE DIVIDED in the middle, or CONTINUOUS?

4. What is the SHAPE OF THE BRAINCASE (front to back) when viewed from above?

5. Is a SAGITTAL CREST present?

6. In NAP, is the FORAMEN MAGNUM oriented more downward OR more to the rear?

7. Is the MASTOID process relatively flat OR does it noticeably protrude (project)?

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II. FACE: (5 items: #8-12)

8. Are the NASAL BONES raised (arched) OR flat?

9. Measure the MAXIMUM BREADTH (width) of the NASAL OPENING [mm].

10. Measure the MAXIMUM HEIGHT of the NASAL OPENING [mm].

11. Measure the LENGTH of the MAXILLA (the upper jaw) [mm]. (Measure down the middle of the palate from the front edge of the foramen magnum to either between or just in front of the two central incisors to determine how much the face projects forward.)

12. Measure the BIZYGOMATIC BREADTH using the hinge caliper if necessary [mm]. (This is the width or breadth of the face from the widest part of one zygomatic arch to the widest part of the other zygomatic arch.)

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III. DENTITION: (6 items #13-18)

13. SHAPE OF THE DENTAL ARCADE: Do the tooth rows diverge towards the back OR are they more straight-sided and parallel to one another?

14. When viewed from the side, are the INCISORS angled out OR are they vertical?

15. Measure the COMBINED WIDTH or BREADTH of the 4 INCISORS together.

16. Does the CANINE tooth project above the chewing surfaces of the other teeth?

17. Is a CANINE DIASTEMA present?

18. Measure the COMBINED LENGTH of the LEFT 2 PREMOLARS and 3 MOLARS together by measuring from the back of the last molar to the front of the first premolar to determine the length of the chewing surface of the "cheek teeth". [mm]. (NOTE: Measure the right side if the left side is missing any of these 5 teeth.)

Read about Evolution of the Hominini ~ Part Two here.

The Walk of Life ~ Part One: From the Pre-Cambrian to the Silurian

 

I've been teaching an awesome Big History class at my local homeschool co-op this past year, and our last class culminated in a walk through the timeline of life.

The idea is to have fossils, pictures, and figures that represent prevailing or significant life that existed in each time period. They are put in a specific box for that time period, and then spread out on a walk so we can 'walk through time'.

I've been putting these boxes together for some years, and originally used them .... six or seven years ago with our Universalist Unitarian church summer camp! The boxes have evolved (just like the life within) and will likely continue to get tweaked.

For the most part, fossils used are contemporary to their time period. But sometimes it is hard to find or afford the exact fossil. So sometimes I use a fossil from a different time period to represent a fossil or life form from a different time. One example would be the turtle fossils in the Permian box. It is difficult to find any reptile fossils (for a price this mama can afford), so I used turtle shell fossils that were very inexpensive from a more recent period. I explained to the kids that in the Permian, some reptiles had osseous skin, or bony skin tissue, that later evolved into a full turtle shell. There are also a few figures in the boxes that I will replace with nicer figures as time goes on.

I've collected pictures from old National Geographic magazines, old text books, free clip art (especially DK Publishers) and from other places on the web. I do not sell or make any profit from this program, so I hope that on the occasion that I've borrowed an image it is OK.

The walk started on a woodland path where our co-op meets (an old Girl Scout camp), and my daughter helped me stage the boxes throughout the path, in order from oldest to most recent time periods. We left the boxes on the path and as the group of kids and I walked the path, we would come upon each box. Each kid got to open a box and lay the items and labels out on a large tray so we could talk about them.

Heading down the woodland path to find the first box....

The kids unpacking the Anthropocene box along the woodland path! 

Each box contains a smaller box with a list of items, small specimens, and pictures. Larger items simply go into the larger box, or separate smaller boxes (that fit inside the large box) where needed.

The list, taped inside each blue plastic box. That way I make sure items don't get shuffled around accidentally.

Here are the contents of each box, in order.

PRECAMBRIAN BOX
Contains glitter in water for cyanobacteria, a cyanobacteria picture, a stromatolite fossil, and stromatolite picture. 

I am now accepting donations of cyanobacteria. :)

Moroccan stromatolite. Inexpensive and easy to find at fossil shows.

CAMBRIAN BOX
Contents: Brachiopods, trilobites and pictures, a modern arthropod specimen (crawdad claw), fossil hash with brachiopods and cute, little trilobites!, and three amazing crafted figures of wiwaxia, opabinium, and a chiton. 

Go here to find these awesome plastic models! I ran into the creator at a MAPS fossil sale this year.

PALEOCASTS

fossil 'hash' with brachiopods and teeny, tiny trilobites!

brachiopods, the one on the right was found in a creek in Central Illinois by my daughter

Seriously, the coolest ever!
PALEOCASTS

ORDOVICIAN BOX
Contents: Graptolite fossil and picture, chain coral fossil, cephalopod picture and two fossils (ammonite, and orthoceras), jawless fish picture and a modern fish vertebra.

Chain coral

graptolites

cephalopods

jawless fish and vertebra

SILURIAN BOX
Contents: Cooksonia plant picture, crinoid stem pieces and hash, crinoid 'sea lily' picture, bryozoan, and insects. (I would like to elaborate more on insects in the future.)

crinoid bonanza! We have a lot of these in Central Illinois, although this hash specimen is from Indiana

bryozoan

insects

These are just cool because they are real insects encased in plastic resin. I found them on super clearance at Toys R Us!

My next blog entry will cover the Walk of Life ~ Part Two: From the Devonian to the Anthropocene!