Prototheria
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.