Main Points
1) Define “mammal”
--taxonomic perspective
--evolutionary perspective
--distinguishing features among classes within
Subphylum Vertebrata
2) Discussion of Ceballos and Ehrlich 2009
3) Characteristics of mammals
--internal soft anatomy
--external anatomy
--will discuss skull in lab
Terms: cladogram, clade, amnion, homeothermy, derived
character, ancestral/primitive character, convergence,
homology, pelage, vibrissae, adaptive coloration (disruptive,
aposematic, cryptic), pinnae, Allen’s rule
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Taxonomic Perspective
Kingdom Animalia (~1,200,000 species)
2
Taxonomic Perspective
Kingdom Animalia (~1,200,000 species)
Phylum Chordata (~63,000 species)
-- dorsal hollow nerve cord (at least in embryos)
-- notochord
-- gill slits
3
Taxonomic Perspective
Kingdom Animalia (~1,200,000 species)
Phylum Chordata (~63,000 species)
-- dorsal hollow nerve cord (at least in embryos)
-- notochord
-- gill slits
Subphylum Vertebrata (~60,000 species)
-- backbone (vertebral column)
-- braincase
-- internal skeleton
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How do vertebrates differ from each other?
• presence of amnion = fluid to protect egg or embryo
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How do vertebrates differ from each other?
• two, three, or four-chambered heart
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How do vertebrates differ from each other?
• homeothermy = near-constant body temperature
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Convergence versus Homology
fossorial
soricomorph
(eastern mole)
fossorial
rodent
(western pocket
gopher)
fossorial
marsupial
(marsupial mole)
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Convergence versus Homology
sanguinivore (Desmodus)
nectarivore (Anoura)
frugivore (Chiroderma)
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Sauropsida
(split occurred
~200-250 MYA)
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Taxonomic Perspective
Kingdom Animalia (~1,200,000 species)
Phylum Chordata (~63,000 species)
-- dorsal hollow nerve cord
-- notochord
-- gill slits
Subphylum Vertebrata (~60,000 species)
-- backbone
-- braincase
-- internal skeleton
Class Mammalia (~5,400 species)
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Roughly two years ago…
olinguito (Bassaricyon neblina)
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Roughly a year ago…
little black tapir (Tapirus kabomani)
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The global distribution of newly discovered
mammals (Ceballos and Ehrlich 2009)
•
roughly 1/10th of the world’s mammals discovered
since 1993
• many of these “morphologically distinct”
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Discussion questions: look at this figure. What
information are the authors trying to convey?
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Some internal characteristics of mammals
1) glandular skin—sweat glands
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Some internal characteristics of mammals
1) glandular skin—sweat glands
mammary glands (modified sweat glands)
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Some internal characteristics of mammals
1) glandular skin—sweat glands
mammary glands (modified sweat glands)
sebaceous glands
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Some internal characteristics of mammals
1) glandular skin—sweat glands
mammary glands (modified sweat glands)
sebaceous glands
scent and musk glands
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Some internal characteristics of mammals
1) glandular skin—sweat glands
mammary glands (modified sweat glands)
sebaceous glands
scent and musk glands
venom glands (not diagnostic)
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Some internal characteristics of mammals
2) young develop in female’s uterus (excepting Prototherians)
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Some internal characteristics of mammals
2) young develop in female’s uterus (excepting Prototherians)
3) large brain, relative to other vertebrates
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Some internal characteristics of mammals
2) young develop in female’s uterus (excepting Prototherians)
3) large brain, relative to other vertebrates
4) well-developed facial muscles
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Some external characteristics of mammals
1) hair—vibrissa (plural: vibrissae)
guard hairs
under hairs
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Adaptive Coloration
• Disruptive coloration
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Adaptive Coloration
• Aposematic coloration
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Adaptive Coloration
• Cryptic coloration
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Adaptive Coloration
• Cryptic coloration
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Some external characteristics of mammals
1) hair
2) pinna (plural: pinnae)
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Some external characteristics of mammals
• Allen’s rule
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