Order Summary for Hexanchiformes

  Main Ref
:
  Order
:
Hexanchiformes frill and cow sharks
  Class
:
Elasmobranchii
  Sister Order
:
Heterodontiformes 195 M years
  Ref..
:
  First Fossil Record
:
middle Jurassic
  Occurs in
:
Marine
Fresh
Brackish
  Remark
:
One dorsal fin, without spine; anal fin present; six or seven gill slits; eyes without nictitating fold; spiracle present but small and well behind eye.
  Classetymology
:
Greek eulanein, elasmos = metal beaten out + Greek brangchia = gills. Ref. 45335.
  Orderetymology
:
Greek, exa = six + Greek, agkone, agko, to strangle, strangulate + Latin, forma = shape (Ref. 45335).
  Families
: