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Chapter 34

Biodiversity Spring 2026- Exam 3

QuestionAnswer
What are the major vertebrate clades in order of evolution? Cyclostomata, gnathostomes, chondrichthyes, osteichthyans, tetrapods
Cyclostomata traits no jaws, no paired fins, notochord retained Jawless fish
Cyclostomata examples hagfish, lampreys
Gnathostomes traits Major evolutionary step: jaws (from pharyngeal arches) Jawed vertebrates
Gnathostomes examples
Chrondichthyes traits Cartilage skeleton, teeth, buoyancy adaptations Carilaginous fish
Chrondichthyes examples Sharks, rays
Osteichthyans traits Actinopterygii (ray-finned) Sarcopterygii (lobe-finned) → gave rise to tetrapods bony fish
Tetrapods traits four limbs
Tetrapods examples Amphibians, reptiles, mammals
Major evolutionary innovations (in order) Notochord, vertebral column, cranium, jaws, lungs/swim bladder, lobed fins, limbs, amniotic egg, hair and mammary glands
What does notochord do? Support
What does vertebral column do? Replaces notochord
What does cranium do? Protects brain
What does jaws do? Better feeding
What does lungs/swim bladder do? Gas exchange
What does lobed fins do? Precursor to limbs
What does limbs do? Movement on land
What does amniotic egg do? Reproduction on land
What does hair and mammary glands do? Mammals
What needed to be adapted for tetrapod transition to land? Structural support Locomotion Gas exchange
What does structural support of tetrapods do? Stronger skeleton Vertebral column strengthened Limbs replaced fins
What does locomotion of tetrapods do? Limbs with digits for walking Muscles adapted for gravity
What are the key adaptions of amniotes? Amniotic egg Internal fertilization Desiccation-resistant skin Thoracic breathing (negative pressure) Water-conserving kidneys
What is the results of the key adaptions of amniotes? No need to return to water to reproduct
Characteristics of reptile groups: turtles Shell (carapace and plastron) Ribs fused to shell Temperature-dependent sex
Characteristics of reptile groups: lepidosaurs (lizards, snakes, tuatara) Kinetic (Flexible) skill Some venomous Loose jaws (snakes swallow large prey)
Characteristics of reptile groups: crocodilians 4-chambered heart Nostrils on top of head Semi-aquatic predators
Characteristics of reptile groups: birds (derived from dinosaurs) Traits adapted for flight: Air sacs (efficient breathing), Lightweight bones, Reduced organs, Feathers Endothermic 4-chambered heart High metabolism
General mammal traits? Hair, mammary glands (milk), specialized teeth, large brain, 3 ear bones, endothermic
What are the 3 major groups of mammals? Monotremes, marsupials, eutherians
Traits of monotremes Lay eggs No placenta
Example of monotremes Platypus
Traits of marsupials Short pregnancy Development in pouch
Traits of eutherians Long gestation Complex placenta Most diverse group
What are the major components of the nervous system? Brain (control center) Spinal cord Peripheral nerves
What are the trends of the nervous system? Increasing brain complexity over evolution Largest in mammals and birds
Notochord definition Flexible support rod Openings for feeding/gas exchange
Pharyngeal definition Openings for feeding/gas exchange
Pharyngeal definition Grooves between arches
Oviparous definition Egg-laying
Ovoviviparous definition Eggs hatch inside parent
Viviparous definition Live birth
Cloaca definition Single exit for waste and reproduction
Operculum definition Gill cover in fish
Amniotic egg defintion Egg with membranes for land survival
Endotherm definition Generates internal heat
Ectotherm definition Relies on environment
Vertebrates definition Animals with backbone
Agnatha definition Jawless fish
Gnathostomes definition Jawed vertebrates
Chondrichthyans definition Cartilage fish
Osteichthyans definition Bony fish
Ray-finned fish definition Thin fin rays
Lobe-finned fish definition Fleshy fins (tetrapod ancestors)
Tetrapod definition Four limbs
Amphibians definition Require water for reproduction
Amniotes definition Fully terrestrial reproduction
Placenta definition Nutrient exchange organ between mother and embryo
Created by: KristenR2025
 

 



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