Chapter  3 - Jawless Vertebrates

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return to vertebrate zoology syllabus

What is a fish?

An Introduction to Fishes -- Comparative Anatomy, Auburn University

WB01342_.gif (412 bytes)  The Earliest Evidence of Vertebrates


Learn  more about craniates from the UCMP or from the Tree of Life


  1. distinct head and brain (cranium)
  2. neural crest cells in association with
  3. epidermal placodes that form specialized [paired] sense organs-pronounced cephalization 
  4. one or more semicircular canals
  5. gills (for respiration) in pharyngeal slits
  6. duplication of the Hox gene complex
  7. Endoskeleton of living tissue, primitively cartilage, later endochondral bone
  8. Unique excretory (paired kidneys) and circulatory systems





Order PETROMYZONTIFORMES (upper Mississippian, middle Pennsylvanian, Recent)

  • Ventral view of oral sucker and mouth of the lamprey. Note the horny rasping teeth.   Image BIODIDAC. used with permission
  •  Many lampreys are parasites of bony fish. Image BIODIDAC. used with permission
  • Information on sea lamprey in the Great Lakes from the USGS.  
  • Sea and River Lamprey from selected fishes of New York State
  • A Lamprey-Based Undulatory Robot from John Ayers.  Learn how lampreys swim.
  • Europeans have long considered lampreys a delicacy.   The lamprey has, so far, failed to whet North American appetites.  Click here for more information and recipes.
  • Learn  more about lampreys from the UCMP or from the Tree of Life






The Origin of Bone and Other Mineralized Tissue

The Origin of Fins

A Problem Posed by Gills

The Transition from Jawless to Jawed Vertebrate
  • Evolution of the vertebrate jaw from the anterior visceral arches (Fig. 3-9)
  • Generalized jawed vertebrate (Fig. 3-10)
  • Derived features of gnathostomes (Table 3.2)
  • Mallatt's hypothesis for the evolution of vertebrate gills and jaws (Fig. 3-12)




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