• First episode of diversification 
  • The best known primitive shark 
  • It arose some 400 million years ago in the Late Devonian 
  • The average length ~ 1 meter 
  • It had long slender jaws with a cylindrical body shape
  • No anal fin, two dorsal fins 
  • ***Terminal mouth*** (like a fish)
  • Jaws fused to its braincase 
  • Fins were stiff and simplistic
  • no claspers (external fertilization?)
  • Symmetrical tail, similar to the modern mackeral  shark in the order Lamniformes 
  • Decent agility and speed
  • It had knifelike spines projecting from its dorsal fins [as seen in drawing] (Fenton and Fenton)
    Drawing by Stefan Grambart
copyright Stefan Grambart, 1999