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Marsupial Characteristics


As previously mentioned marsupials belong to the Mammalian Order and therefore share all possess all these defining characteristics, however, in addition, they have the following features:

 

Special Characters:


1. Polyprotodont versus diprotodont


This refers to whether the lower incisors are many and equal in size (Polyprotodont) or whether the medial incisor is greatly enlarged (Diprotodont).

 

 Polyprotodont

 Diprotodont

 

 

Lower jaw of Didelphis (Didelphidae) illustrating the multiple, equally sized incisors.

 

Lower jaw of Caenolestes (Caenolestidae) illustraing the enlarged anterior inciscor and the multiple small posterior ones.

Lower jaw of Macropodidae (Macropodidae) illustrating how sometimes a single enlared incisor can be present.
Pictures reproduced from http://www.csus.edu/

2. Polydactyly versus syndactyly


In the polydactyly condition all the digits of the hind foot are free and approximately equal in size, whereas in the syndactyly condition the digits two and three are distinctly smaller and encased in a common sheath of skin.

 Polydactylous

 Syndactylous

 

e.g. Didelphidae

 

e.g. Dasyuridae

 

e.g. Peramelidae

 

e.g. Phascolartidae

 

e.g. Macropodidae

Pictures reproduced from http://www.csus.edu/

 

 

3. Tribosphenic Molar

the basic tribosphenic molar (both upper and lower) of a metatherian is distinguishable from that of a eutherian mammal.



Author: Catrin Roberts
Last updated: 23.11.83
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