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Chordate Phylogeny & Evolution of Gnathostomes and Osteichthyes, Lecture notes of Biology

A comprehensive overview of Chordate Phylogeny, focusing on the evolution of Gnathostomes and Osteichthyes. Topics covered include the sister taxon to Chordates, basal Chordates, Jawless Vertebrates, Gnathostomes, Chondrichthyes, Osteichthyes, and various fish lineages. Discussions include the development of skeletons, tooth structures, reproductive adaptations, and respiratory systems.

What you will learn

  • How did the respiratory systems of Chondrichthyes and Osteichthyes evolve?
  • What is the evolutionary history of Chordates?
  • What are the differences between Chondrichthyes and Osteichthyes?
  • How did the development of skeletons impact the evolution of fish?
  • What are the various reproductive adaptations in Chondrichthyes?

Typology: Lecture notes

2017/2018

Uploaded on 09/13/2021

mjm245
mjm245 🇺🇸

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Chordates: Chordate Phylogeny
CBJ Ch. 34 - 1
sister taxon to chordates
basal chordates
Jawless vertebrates
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Chordates: Chordate Phylogeny

CBJ Ch. 34 - 1

sister taxon to chordates

basal chordates

Jawless vertebrates

2

Gnathostomes: Chondrichthyes

• Chondrichthyes: cartilaginous fish

– All with skeleton of cartilage

• ancestors had mineralized bones

Gnathostomes: Chondrichthyes

  • (^) bone minerals lost to reduce density
    • buoyancy raised by liver oils & active swimming

CBJ Ch. 34 - 5

Gnathostomes: Chondrichthyes

  • (^) Most are active predators, marine

CBJ Ch. 34 - 7

great white shark^ great white shark

hammerhead shark^ hammerhead shark

spiral valve increases surface area for digestion & absorption!

spiral valve increases surface area for digestion & absorption!

nostril^ nostril eye^ eye

bony teeth^ bony teeth

Gnathostomes: Chondrichthyes

  • (^) but a few filter-feed; some live in fresh water

CBJ Ch. 34 - 8 whale shark , a filter-feeder whale shark , a filter-feeder

Gnathostomes: Chondrichthyes

  • (^) Some ovoviviparous: egg retained within mother; embryo fed by egg yolk ;

live birth

CBJ Ch. 34 - 10

Gnathostomes: Chondrichthyes

  • (^) Some viviparous: embryo fed directly by maternal tissue; live birth

“^ “umbilical cord”umbilical cord”

Gnathostomes: Chondrichthyes

• manta raymanta ray

sting ray^ sting ray

skate^ skate

skate teeth for grinding mollusks^ skate teeth for grinding mollusks

Gnathostomes: Chondrichthyes

CBJ Ch. 34 - 14

gill slits^ gill slits

mouth^ mouth

underside of manta ray

(filter-feeders)

underside of manta ray

(filter-feeders)

Gnathostomes: Chondrichthyes

sawfish underside^ sawfish underside

mouth^ mouth^ gillsgills

Gnathostomes

“bony fish”

ray-finned^ ray-finned

coelocanth

lungfish lobe-finned^ lobe-finned

Gnathostomes: Osteichthyes

  • (^) first lungs helped fish in low-O 2 freshwater
    • swallowed air into digestive tract
    • outpocketing of esophagus increases surface area
  • (^) later, lungs modified into swim-bladder for buoyancy

a swim bladder is a “lung derivative”

a swim bladder is a “lung derivative”

Gnathostomes: Osteichthyes

  • (^) Skeletons remain mostly ossified (mineralized)