Lecture Notes on Various Biological Concepts

Fish and Ventilation

• Ray-finned Fish: To hover and ventilate gills effectively, uses operculum besides the swim bladder.

Tunicates and Pharyngeal Gill Slits

• Blockage: Leads to difficulty in respiring and feeding.

Amniotes

• Groups of Amniotes: Includes turtles.
• Embryo Development: In water because amnion encases each embryo in water.
• Success in Dry Environments: Due to shelled, amniotic egg.

Characteristics of Monotremes and Marsupials

• Shared Trait: Both have some embryonic development outside the uterus.

Identifying Organisms

• Hiking Observation: To distinguish between a snake or amphibian, check for presence of scales.
• Chordates:
  • Most like earliest chordates in appearance are lancelets.
  • Fossil identification between reptile or mammal, examine teeth.

Vertebrate Evolution

• First Structures: Earliest mineralized structures involved in feeding.
• First Structures in Chordate Evolution: Paired fins.
• Bipedalism Evolution Trait: Repositioning of foramen magnum.

Mammals and Birds

• Feeding Habits: Eat more often than reptiles because of amniotic egg.

Amniotic Egg Structure

• Closest to Embryo: The amnion.

Bird Respiratory System

• Air Sacs: Despite not being thin/highly vascularized, they contribute to efficient respiration; not sites of gas exchange.

New Aquatic Chordate Species

• Characteristics include external armor of bony plates, no paired lateral fins, suspension-feeding.
• Likely characteristic: no jaws.

Geographic Distribution of Marsupials

• Found in Australia and the Americas.

Common Ancestor of Tetrapods

• Likely a sturdy-finned, shallow-water lobe-fin with appendages similar to terrestrial vertebrates.