Prototheria

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 Prototheria

(Gr., protos-first + theria- beast)
Primitive, reptile like , oviparous (Eg. Echina ‘spiny anteater’)

General feartures :-

  • Marsupials brood pouch on the ventral side
  • occupy a wide variety of niches and varied in diets
  • Viviparous 
  • warm blooded
  • Body covered by hair
  • Pinna well developed
  • Mammary  glands have tits
  • All digits are clawed
  • Skull dicondylic
  • Mandible is a single bone called is Dentary
  • Orbital  and temporal fossa and are congruent 
  • Seven cervical vertebrae is Y shaped bones in caudal vertebrae 
  • 4 th toe is largest in hind limb, serves as axis of foot
  • Clavicle is well developed. Inter- clavicle is absent
  • Penis is present in  some animal it is bifurcated
  • Fertilisation and initial development is internal
  • Young ones are born in an immature state
Affinity with prototheria :-                                                                
  • Cloaca presents                                               
  • Play vehicle present.                       
  • Corpus callosum absent.                                                    
  • Placenta is not found.   
Affinity with eutheria :-
  • Vagina is present 
  • Cochlea is coiled
  • Viviparous
  • Pinna is present
  • Heterodont
                                                         

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