Introduction

What was the start of mammalogy like?

What is the American Society of Mammologists?

What is the difference present mammalogy and past mammalogy?

What is dentary squamosal jaw articulation?

Single jaw bone that articulates on a jaw joint

What are the three middle ear ossicles?

• Tympanum moves the middle ear ossicles, and the movement of the ear ossicles causes the fluid to vibrate

• Incus, Malleus, and Stapes (evolved from jaw bones)

What are the two occipital condyles benefits?

What are ossified epiphyses on the long bones?

• Epiphyseal closure determines the maturity of the mammal (cartilage in bones make it as sub-adult, no cartilage makes it an adult

What is the secondary palate in mammals?

• A bone structure that separates oral and nasal cavities

• Allows more efficient respiration

• Facilitates nursing

What is the purpose of hair on mammals?

• Primarily functions in insulation and mechanoreception

What are mammary glands?

• provide nourishment to developing young

• Opening are in projecting nipples or teats

Explain the 4-chambered heart

• Complete separation of pulmonary and systemic circulation

Explain Biconcave enucleate erythrocytes

• Red blood cells with no nucleus and concave on both sides

• Allows for more surface area to bind oxygen

Explain muscular diaphragm

Separates abdominal cavity from thoracic cavity

When did mammals first appear?

What were the early amniotes like?

What is an amniotic egg?

• a self-contained reproductive package with specialized membranes that allows animals to reproduce on dry land without needing water

• Amnion: A fluid-filled sac that cushions and surrounds the embryo, keeping it hydrated.

• Yolk Sac: A structure that supplies vital nutrients and energy to the growing embryo.

• Allantois: A sac that stores waste products and helps with gas exchange

• Chorion: An outer membrane that works with the allantois to handle oxygen and carbon dioxide exchange.

What are the lineages of amniotes?

• Diapsida and Synapsida

  • Characterized by the number of temporal openings in the skull

• Diapsid Skull: 2 openings

• Synapsid Skull: 1 openings

What was the synapsid lineage?

What were the pelycosaurs?

What were the therapsids?

What were the cynodonts?

What are the lower jaw adaptations?

• Increase in the dentary bones

• The jaw articulation was moved forward and more area for muscle attachment

• Reduce stress on the jaw joint (joint is in middle of the muscles)

• Greater bite force

What are the middle ear adaptations?

• Quadrate and articular moved into the middle ear as Incus and Malleus

  • 3 bones amplify sound waves- “impedance matching”

  • Fluid in the cochlea provides greater resistance

  • The middle ear acts as an impedance-matching device that bridges the resistance gap between low-impedance airborne sound waves and the high-impedance fluid of the inner ear

What are the adaptations for teeth?

• Tricuspid, double-rooted post-canine teeth

  • Differentiate teeth for eating different food

  • Greater efficiency and adaptability in feeding

What are the adaptations for vertebrae?

• Lost of abdominal ribs or lumbar ribs allowed for more flexibility

What were the adaptions for locomotion?

• Modifications of the limb girdles to allow a more erect posture

• More efficient locomotion

What were the size of Mesozoic mammals?

• Small

  • Mouse to opossum-sized

  • Smaller than early synapsids

Were Mesozoic mammals ectothermic or endothermic?

• Endothermic

  • Hair

  • Greater mobility

  • Differentiated teeth

  • Muscular diaphragm

  • Turbinate bones (lattice-like structure for more olfactory receptors and evaporate cooling in the rostrum)

Were Mesozoic mammals diurnal or nocturnal?

• Nocturnal

  • Enlarged cerebrum (reduction in optic lobes of the brain)

  • Secondary palate- sense of smell could increase

  • Enhanced hearing (3 ear ossicles)

  • Sensory hairs (vibrasse)

What were the feeding habits of Mesozoic mammals?

• Insectivorous

  • Sharp cusps on the cheek teeth; similar to modern mammals

Why were the Mesozoic mammals remained small and nocturnal?

• Competitive exclusion (Competition with dinosaurs)

• Physiological constraints

  • Evaporative cooling (small size, requires no specializations)

  • Energy intake

  • “Evolutionary Fuse” hypothesis- specializations take a long time to appear for cooling and energy intake