chapter 43 mammals
DESCRIPTION
Chapter 43 Mammals. Section 1 Origin and Evolution of Mammals. Characteristics. Endothermy - regulate own body temperature- metabolism Hair - all mammals have some hair- made of keratin Completely divided heart- four-chambered heart- no mixing of blood. Characteristics. - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 43Mammals
Section 1
Origin and Evolution of Mammals
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Characteristics• Endothermy- regulate own body
temperature- metabolism• Hair- all mammals have some hair-
made of keratin• Completely divided heart- four-
chambered heart- no mixing of blood
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Characteristics• Milk- females produce milk to feed
offspring- made of fats, proteins, and sugars– Produced by mammary glands- modified sweat
glands located on thorax or abdomen
• Single jawbone- fossils identified by bones
• Specialized teeth- for eating
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Ancestors of Mammals• Synapsids- gave rise to mammals
• Single opening in a bone behind eye socket
• Looked like modern lizards
• Specialized teeth
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Therapsid• Also gave rise to mammals
• Rich fossil record of transitional forms between therapsids and mammals exists
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Early Mammals• Dinosaurs co-existed with
mammals
• Early mammals were about the size of a mouse
• Large eye sockets suggests that early mammals were active at night
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Diversification of Mammals• Monotremes- oviparous- lay
eggs• Marsupials- viviparous- give
birth to live young- young develop in pouch
• Placental mammals- viviparous- develop in mother’s uterus- nutrition from placenta
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Monotremes
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Marsupials
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Placental Mammals
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REVIEW!!!• What is the function of hair in
mammals?
• Differentiate between monotremes, marsupials, and placental mammals.