bio final ch 34

• first appeared in the earliest tetrapods


  limbs with digits
• in ray-finned fish, the fins allow invididuals to perform which two functions?


  maneuvering and defense
• in gnathostomes, the skeletal rods that supported the pharayngeal slits may have evolved into which structure?


  jaw
• a mechanoreceptor system consisting of a series of pores and receptor units along the sides of the body in fished and aquatic amphibians; detects water movemnets made by the animal itself and by other moving objects

  lateral line system
• most fish can maintain a bouyancy when this fills


  swim bladder
• which group of animals retains all 4 key chordate characteristics as an adult?


  lancelets
• derived characteristics of all chordates except

  neural crest cells
• tiktaalik had all the following characteristics except:

  neck

  gills

  lungs

  ribs

  tiktaalik had all of the above structures
• vertebrates and tunicates both possess


  a notochord and a dorsal, hollow nerve chord
• characteristic of only mammals


  hair and fat layer
• which group of organisms have jaws

  myxini - hagfishes

  urochordata - tunicates

  petromyzontida - lampreys

  dipnoi - lungfishes

  dipnoi - lungfishes
• best explains why reptiles can survive on less than 10% of the food energy required by mammals of the same size


  reptiles are ectothermic
• the following are characteristics of which group of chordates?

  chemical sensors

  heat-detecting organs

  venom

  loosely articulated jawbones and elastic skin

  lepidosaurs
• all vertebrates are gnathostomes (have jaws) except which two groups?

  myxini (hagfishes)

  petromyzontida (lampreys)
• of all chordates, which two groups are not considered vertebrates?

  urochordata

  cephalochordata
• derived set of characteristics of all chordates


  notochord

  dorsal, hollow nerve chord

  post-anal tail
• longitudinal, flexible rod located between the digestive system tube and the nerve chord

  notochord
• the dorsal, hollow nerve chord develops from


  plate of ectoderm that rolls into a neural tube
• cephalochordata


  lancelets; retain characteristics of the chordate body plan as adults
• urochordata


  tunicates; most resemble chordates during larval stage
• the earliest vertebrates lacked


  jaws
• gnathostomes are vertebrates that


  have jaws; enlarged forebrain: enhanced senses of smell and vision
• chondrichthyans have a skeleton composed

  primarily of cartilage; big liver full of oil for buoyancy
• osteichthyans


  mineralized bones; swim bladder; fish
• actinopterygii (ray-finned fish)


  fins modified for maneuvering and defense
• sarcopterygii (lobe-finned fish)


  rod-shaped bones; thick layer of muscle

  actinistia, dipnoi, and tetrapods!
• dipnoi (lungfishes)


  gills and lungs
• tetrapods are gnathostomes


  four limbs; feet with digits

  fusion of pelvic girdle to backbone

  pharyngeal slits during embryologic development

  ears for detecting airborne sounds
• origin of tetrapods -- tiktaalik


  fish characteristics: scales, fins, gills and lungs

  tetrapod characteristics: neck, ribs, fin skeleton, flat skull, eyes on top of skull
• additional derived characteristics of tetrapods


  C1 (atlas) and C2 (axis) vertebra
• amphibia


  aquatic larva and terrestrial adult

  moist skin
• amniotes


  tetrapods that have a terrestrially adapted egg
• reptiles


  shelled amniotic eggs

  scales --> keratin

  ectothermic
• archosaurs


  turtles
• origin of birds


  early feathers might have evolved for insulation, camo, or courtship display
• derived characteristics of birds


  keratin feathers

  weight-saving adaptations (no urinary bladder)

  endothermic
• lepidosaurs


  squamates, lizards, snakes
• snakes (lepidosaurs)


  heat-detecting organs

  venom

  loosely articulated jawbones and elastic skin
• mammals are amniotes


  have hair and produce milk

  endothermy -- result of convergence!