mammalian characteristics:

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Mammalian characteristics: ranial (skull) eatures

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Mammalian characteristics:. Cranial (skull) features. Lizards & snakes Crocodiles Dinosaurs & birds. Mammals & reptile-like mammals. Turtles. Anapsida. Diapsida. Amphibians. Saurapsida. Synapsida. -ca. 320 mya. Amniota. -evolution of cleidoic (shelled) egg; - PowerPoint PPT Presentation

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Page 1: Mammalian  characteristics:

Mammalian characteristics:

Cranial (skull) features

Page 2: Mammalian  characteristics:

Anapsida Diapsida

SynapsidaSaurapsida

Turtles

Lizards & snakesCrocodilesDinosaurs & birds

Mammals &reptile-like mammals

Amniota -evolution of cleidoic (shelled) egg; ca. 350 mya (late Paleozoic)

Amphibians

-ca. 320 mya

Page 3: Mammalian  characteristics:

-apsid conditions

Anapsid Synapsid Diapsid

PelycosaurModern mammal

Page 4: Mammalian  characteristics:

Double occipitalcondyle:

greater range of motion

Page 5: Mammalian  characteristics:

Pelycosaur

Therapsid

s

Single bone in mandible: dentary

Page 6: Mammalian  characteristics:

post-dentary bones

Dentary-squamosal articulation

Page 7: Mammalian  characteristics:

Reptile:

Mammal:

stapes

stapes

stapes

(incus)

incusmalleus

(malleus)

(stapes)(incus)

(malleus)

3 inner ear ossicles

Page 8: Mammalian  characteristics:

Tympanic bone (="annulus" or "tympanic ring")

tenrec skull; no auditory bulla

Page 9: Mammalian  characteristics:

Mammalian characteristics:Dental features

Page 10: Mammalian  characteristics:

Heterodont dentition

Page 11: Mammalian  characteristics:

Diphyodonty (vs. polyphyodonty)

Page 12: Mammalian  characteristics:

Matched shear surface on upper & lower teeth

Page 13: Mammalian  characteristics:

Complex occlusal surface on cheeckteeth

Page 14: Mammalian  characteristics:

Secondary palate

Page 15: Mammalian  characteristics:

Mammalian characteristics:Postcranial (skeletal) features

Page 16: Mammalian  characteristics:

Modified limbs and pelvic girdle

Reptile-like Mammal-like

Sprawling posture Upright postureLateral gait Fore-aft gaitPoorly developed calcaneus Well-developed calcaneus

calcaneus

fibula

femur

tibia

pelvicgirdle

calcaneus

fibulatibia

femur

astragalusastragalus

Page 17: Mammalian  characteristics:

Indeterminite growth vs. Determinite growth

Long-bone epiphyses

Page 18: Mammalian  characteristics:

Stabilized and regionally specialized vertebral column

Page 19: Mammalian  characteristics:

AtlasAtlas Axis

Dorsal-ventralflexion Rotation

Page 20: Mammalian  characteristics:

Simplified skeleton

Page 21: Mammalian  characteristics:

Mammalian characteristics:Soft anatomy, sensory,

and physiological features

Page 22: Mammalian  characteristics:
Page 23: Mammalian  characteristics:

Hair (=fur or pelage)

Page 24: Mammalian  characteristics:

Mammal hair:invagination Bird feather: evagination

Page 25: Mammalian  characteristics:

cuticle

cortex: pigment

medulla: dead cells containing air; variably present.

Hair structure

Page 26: Mammalian  characteristics:

New PNAS article on originof hair: PNAS November 25, 2008 vol. 105 no. 47 18419-18423

Page 27: Mammalian  characteristics:

Hair function: tactile perception (vibrissae)

Page 28: Mammalian  characteristics:

Hair function: locomotory specializations

Page 29: Mammalian  characteristics:

Hair function: defense

Page 30: Mammalian  characteristics:

Hair function: aggression and display

Page 31: Mammalian  characteristics:

Hair function: communication

Page 32: Mammalian  characteristics:

Mammary glands (=mammae), structural variation

Monotreme Nipples(most mammals)

Teat(e.g., cows)

Skin glands

Page 33: Mammalian  characteristics:
Page 34: Mammalian  characteristics:

4-chambered heart

Mammal

Crocodyle

Page 35: Mammalian  characteristics:
Page 36: Mammalian  characteristics:

Enucleated blood cells

Muscular diaphragm

Page 37: Mammalian  characteristics:

Improved olfaction

Page 38: Mammalian  characteristics:

Endothermy---Body temperature regulated internally.

Homeothermy---Body temperature maintained within a narrow range.

Page 39: Mammalian  characteristics:

An integrated package?

•Natural selection favored increasingly efficient use of energy

•Endothermy facilitated nocturnal activity

•Endothermy is especially difficult for young

•Diphyodonty, lactation, social behavior

Page 40: Mammalian  characteristics:
Page 41: Mammalian  characteristics:

Did these all appear simultaneously????

How do we know???

Page 42: Mammalian  characteristics:

Occipital condylesDentary, ear ossiclesDentitionUpright postureDeterminite growth/ephiphysesSimplification of skeletonVertebral columnMammary glands4-chambered heartEnucleated red blood cellsDiaphragmEndothermy/homeothermyOlfactionHair

Fossil evidence?

Page 43: Mammalian  characteristics:

Occipital condylesDentary, ear ossiclesDentitionUpright postureDeterminite growth/ephiphysesSimplification of skeletonVertebral columnMammary glands4-chambered heartEnucleated red blood cellsDiaphragmEndothermy/homeothermy(??)Olfaction (??)Hair

Fossil evidence?