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Main Points
1) Defining “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)1
Kingdom Animalia (~1,200,000 species)
Phylum Chordata (~63,000 species)
-- dorsal hollow nerve cord (at least in embryos)
-- notochord
-- gill slits
3
Some 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
4
Some taxonomic perspective
How do vertebrates differ from each other?
• presence of amnion = fluid to protect egg or embryo
7
Convergence versus homology
fossorial
marsupial
(marsupial mole)
fossorial
rodent
(western pocket
gopher)
fossorial
afrosoricid
(golden mole)
10
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)
13
Some taxonomic perspective
18
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”
1) glandular skin: sweat glands
mammary glands (modified sweat glands)
Some internal characteristics of mammals
21
1) glandular skin: sweat glands
mammary glands (modified sweat glands)
scent and musk glands
Some internal characteristics of mammals
22
1) glandular skin: sweat glands
mammary glands (modified sweat glands)
scent and musk glands
venom glands (not diagnostic)
Some internal characteristics of mammals
23
2) young develop in female’s uterus (excepting Prototherians)
Some internal characteristics of mammals
24
2) young develop in female’s uterus (excepting Prototherians)
3) large brain, relative to other vertebrates
Some internal characteristics of mammals
25
2) young develop in female’s uterus (excepting Prototherians)
3) large brain, relative to other vertebrates
4) well-developed facial muscles
Some internal characteristics of mammals
26
1) hair: vibrissa (plural: vibrissae)
guard hairs
under hairs
Some external characteristics of mammals
27