Questions and Answers
What classifies a mammal? (Select all that apply)
What are the 3 subclasses of mammals?
Prototheria, Metatheria, Eutheria
What are Prototheria?
Egg laying mammals
What are Metatheria?
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What are Eutheria?
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Where is the only place in the world that has all three subclasses of mammals?
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Why are there so many more marsupials in Australia than placentals?
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Where did marsupials originate and then migrate?
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Why did marsupials do well in Australia but not South America?
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What happened to Australia during the Pliocene?
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Describe Australian rodents.
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What are the two major groups of Australian rodents?
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Why did 90% of megafauna die off after humans arrived?
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Where did monotremes evolve?
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What are reptilian characteristics?
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What are mammalian characteristics?
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Is a platypus a mammal?
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What do platypuses eat?
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What is the purpose of the male venomous spur in platypuses?
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What is the short-beaked echidna?
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Where are marsupials found?
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What do Dasyuridae eat?
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How many species are found in the Dasyuridae family?
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Why is the Tasmanian devil extinct on the mainland?
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How is the Tasmanian devil being stopped from going extinct?
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How does the virus get spread within Tasmanian devils?
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Describe the Numbat.
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What animals are killing off the Numbats?
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What was the Thylacine?
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How did the Thylacine go extinct?
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Describe Bandicoots.
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Describe the pig-footed bandicoot.
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Describe the bilby.
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Study Notes
Classification of Mammals
- Mammals are characterized by having fur, feeding their young on milk, possessing a single lower jaw bone, being warm-blooded (endotherms), a left-curving main artery from the heart, and a diaphragm.
Subclasses of Mammals
- Three subclasses:
- Prototheria (monotremes) - egg-laying mammals.
- Metatheria (marsupialia) - pouched mammals.
- Eutheria (placentals) - mammals with a well-developed placenta.
Geographic Distribution of Mammals
- Australiasia, encompassing Australia and New Guinea, is the only region where all three subclasses of mammals coexist.
- Marsupials likely migrated to Australia before it became an isolated continent, leading to their dominance there.
Evolution and Migration
- Marsupials originated in the Northern Hemisphere (North America and China), spread to Antarctica, South America, and then Australia.
- In Australia, marsupials outcompeted placentals due to slower reproduction rates and lower nutritional needs.
Environmental Changes
- During the Pliocene (5.3 - 2.6 million years ago), Australia underwent significant warming and drying, leading to the development of dry forests and savannas.
Australian Rodents
- Rodents entered Australia from Southeast Asia around 5 million years ago, displaying high levels of species endemicity.
- Two major groups:
- Old Endemics - the most diverse and interesting.
- New Endemics.
Megafauna Extinction
- Approximately 90% of megafauna became extinct after human arrival primarily due to hunting pressures.
Monotreme Evolution
- Monotremes evolved in Australia.
Characteristics of Reptiles and Mammals
- Reptilian characteristics include egg-laying, a single excretory and reproductive opening, and extra bones in the pectoral girdle.
- Mammalian characteristics encompass fur, milk production, and a single lower jaw bone.
Unique Species
- The platypus is a mammal that consumes water invertebrates and has a male venomous spur used to compete during mating.
- The short-beaked echidna feeds on ants and termites with its long tongue and lays only one egg at a time.
Distribution of Marsupials
- Marsupials inhabit almost all types of environments.
Dasyuridae Family
- The family Dasyuridae comprises 57 species that primarily eat small insects and are carnivorous.
Tasmanian Devil
- The Tasmanian devil became extinct on the mainland due to predation by dingoes and a virus causing facial tumors; efforts are underway to enhance their immunity and protect the species.
Numbat and Threats
- The numbat specializes in termite eating, inhabits dry woodlands, and exhibits diurnal behavior, but faces threats from foxes and cats, with fewer than 1,000 remaining.
Thylacine
- Known as Australia’s largest carnivore, the thylacine was extinct by the 1930s due to hunting driven by the perception of it as a predator.
Bandicoots
- Bandicoots are nocturnal, omnivorous mammals with excellent hearing, adaptable to various Australian environments.
Pig-footed Bandicoot
- An extinct species of bandicoot that inhabited dry central Australia and was primarily herbivorous.
Biliby
- A naturally significant species but additional context is required for further details.
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Description
This quiz covers the classification of mammals, their distinct characteristics, and the three main subclasses: Prototheria, Metatheria, and Eutheria. Additionally, it explores the geographic distribution and evolutionary history of these groups, particularly in Australia. Test your knowledge on the fascinating world of mammals!
