Order Summary for Heterodontiformes

  Main Ref
:
  Order
:
Heterodontiformes bullhead and horn sharks
  Class
:
Elasmobranchii
  Sister Order
:
Orectolobiformes 170 M years
  Ref..
:
  First Fossil Record
:
middle Jurassic
  Occurs in
:
Marine
Fresh
Brackish
  Remark
:
Two dorsal fins, each with a spine; anal fin present; five gill slits; eyes without nictitating fold; spiracle present but small; nostrils connected with mouth by deep grove.
  Classetymology
:
Greek eulanein, elasmos = metal beaten out + Greek brangchia = gills. Ref. 45335.
  Orderetymology
:
Greek, heteros = other + Greek, odous = teeth + Latin, forma = shape (Ref. 45335).
  Families
:
( n = 1 ) -
Heterodontidae

Ref.
[ e.g. 9948]                       
Glossary
                    [ e.g. cephalopods]

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