Transcript Mammals of the Badlands By Christina Hurley

Mammals of the
Badlands
By Christina Hurley
Badlands:
Geologic History
Started forming about 75 million years ago
Are composed of 6 different formations
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Pierre Shale
Yellow Mounds
Chadron Formation
Brule Formation
Rockyford Ash
Sharps Formation
Pierre Shale
Deposited 69-75 mya by shallow inland
sea
Black mud hardened to shale
Fossil clams, ammonites, and sea reptiles
have been found
Yellow Mounds
Weathered black ocean mud
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Had been exposed from formation of the
Black Hills
Example of fossil soil (paleosol)
Chadron Formation
Deposited 34-37 mya
River flood plain
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New floods would make each deposit
Known for titanotheres fossils (large,
rhinoceros-like mammals)
Brule Formation
Deposited 30-34 mya
Open savannah
Bands of sandstone show rivers
Red bands
paleosol
Oreodonts (sheep-like animals) dominated
Rockyford Ash
Volcanic Ash
Bottom layer of Sharps Formation
Serves as a boundary between Sharps
and Brule Formations
Sharps Formation
28-30 million years old
Deposited by wind and water
Volcanic eruptions from the west provided
ash
Paleontology
Hyracodon
Subhyracodon
Metamynodon
Tapiroids Colodon
Protapirus
Mesohippus
Miohippus
Archaeotherium
Protoceras
Hyaenodon
Poebrotherium
Oreodont
Nimravid
Hesperocyon
Hesperocyon
Hesperocyon
“Mongoose-like mammal”
One of the earliest Canidae family
members
Spent little time in the trees and hunted
mostly on the ground
Had retractable claws to allow ground
walking and climbing trees
“There once was a goose named Mon. He was a
mongoose.” – Allison Moon
Mesohippus celer
Mesohippus celer
Means “middle horse”
Appeared suddenly
(geologically
speaking)
Preceding horses had
4 toes, Mesohippus
only had 3
Cerebral hemispheres
notably larger
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Brain more distinctly
equine
Last 3 premolars are
like the 3 molars
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Like today’s horses
have 6 grinding cheek
teeth
Leptauchenia nitida (Oreodont)
Leptauchenia nitida (Oreodont)
Called “ruminants hogs”
Have distinctive canine teeth
High set eyes and nostrils suggest aquatic
life-style
Clawed toes indicate terrestrial habitat
Debated whether it is related to pigs or
sheep
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It’s a SHIG!
Nimravids
Nimravids
Are not saber-toothed cats, not even true
cats
Illustrates parallel evolution
Differences are:
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Paths of various nerve and blood vessels in
skull are more primitive
Lack a two-chambered auditory bulla
Teeth are more coned shaped
No modern relatives – truly extinct
B - nimravid; A, C - felids; D - marsupial
Illustration of different evolution
theories. Third being the most
current.
Conclusion
Hesperocyon – brought dogs down from
the trees
Mesohippus celer – 4 toes down to 3,
more equine like brain
Oreodont – importance still unknown
Nimravids – shows parallel evolution
References
http://fossilmuseum.net/Fossil_Sites/badlands.html
http://fossilmuseum.net/Fossil_Galleries/Mammalia/Oreo
dont/Oreodont.htm
http://talkorigins.org/faqs/horses/horse_evol.html
http://laelaps.wordpress.com/2007/06/28/just-what-is-animravid-anyway/
http://www.nps.gov/badl/upload/07Newspaper.pdf
Warren, Dean M.. Small Animal Care and Management.
2. Thomson Delmar Learning, 2002.