Metatheria Infraclass
"behind-beasts" "sort-of-beasts" "pouched animal"
Bilateral symmetry is found through out this infraclass.
What distincts this infraclass from any other is that they carry their young in a pouch.
virginia opossum / Didelphis virginiana
They don't sleep upside down with their tails
bandicoot- bilby / Macrotis lagotus
They live in suburban Austrailian backyards
koala / Phascolarctos cinereus
They have two connected thumbs on each forepaws to help them climb trees
The next closest related group is called Eutheria.
They shared a common ancestor with humans arouynd 120 m.y.a.
Our interaction with them is that we destroy thier habitat.
Reproduction
Intercourse. The female has two lateral vaginas, which match up with the male's two-pronged penis.
Life Cycle
All marsupials are born premature after birth and gestation is around 30 days.
Control
Metatherians obtain control through the spinal cord.
How do they move?
Depending upon the organism they eithier move on two legs or four.
Fun fact
Marsupials do not form male-female bonds that extend beyond the time necessary for mating, and the female cares exclusively for the young.
Citation
http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMetatheria&sa=D&sntz=1&usg=AFQjCNEi_V9zz4aMDE_ItgPtythPErOfPg
http://www.google.com/url?q=http%3A%2F%2Fwww.audioenglish.net%2Fdictionary%2Fmetatheria.htm&sa=D&sntz=1&usg=AFQjCNEHPTUYPwuZPRe7WlXA_1TpvUUtXA
http://www.google.com/url?q=http%3A%2F%2Fanimaldiversity.ummz.umich.edu%2Faccounts%2FMetatheria%2F&sa=D&sntz=1&usg=AFQjCNG8BNBAy_FWltIJ-qM9kCrYDxvOgg
http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEutheria&sa=D&sntz=1&usg=AFQjCNGHxhCrR7eFVsNAvBQwZhSPnIqUUQ
http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMarsupial&sa=D&sntz=1&usg=AFQjCNHKkG5dgUeJI8OLUFLWgjTLC_cESQ
http://www.google.com/url?q=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Fissues%2F164293%2F&sa=D&sntz=1&usg=AFQjCNFEQWl_SyiA9GMg8YPwPQ1Ye8dJrw
http://www.google.com/url?q=http%3A%2F%2Fwww.pbs.org%2Fwgbh%2Fevolution%2Flibrary%2F01%2F4%2Fpdf%2Fl_014_02.pdf&sa=D&sntz=1&usg=AFQjCNGIz2SurRY9ecDdQqt3-PRAGRvwdw
http://www.google.com/url?q=http%3A%2F%2Fwww.pbs.org%2Fwgbh%2Fevolution%2Flibrary%2F01%2F4%2Fpdf%2Fl_014_02.pdf&sa=D&sntz=1&usg=AFQjCNGIz2SurRY9ecDdQqt3-PRAGRvwdw
http://www.google.com/url?q=http%3A%2F%2Fwww.enchantedlearning.com%2Fsubjects%2Fmammals%2Fmarsupial%2FBandicootprintout.shtml&sa=D&sntz=1&usg=AFQjCNG2cLAb78qFwP-_QfMa9dzu6xhGGw
http://www.google.com/url?q=http%3A%2F%2Fwww.audioenglish.net%2Fdictionary%2Fmetatheria.htm&sa=D&sntz=1&usg=AFQjCNEHPTUYPwuZPRe7WlXA_1TpvUUtXA
http://www.google.com/url?q=http%3A%2F%2Fanimaldiversity.ummz.umich.edu%2Faccounts%2FMetatheria%2F&sa=D&sntz=1&usg=AFQjCNG8BNBAy_FWltIJ-qM9kCrYDxvOgg
http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FEutheria&sa=D&sntz=1&usg=AFQjCNGHxhCrR7eFVsNAvBQwZhSPnIqUUQ
http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FMarsupial&sa=D&sntz=1&usg=AFQjCNHKkG5dgUeJI8OLUFLWgjTLC_cESQ
http://www.google.com/url?q=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Fissues%2F164293%2F&sa=D&sntz=1&usg=AFQjCNFEQWl_SyiA9GMg8YPwPQ1Ye8dJrw
http://www.google.com/url?q=http%3A%2F%2Fwww.pbs.org%2Fwgbh%2Fevolution%2Flibrary%2F01%2F4%2Fpdf%2Fl_014_02.pdf&sa=D&sntz=1&usg=AFQjCNGIz2SurRY9ecDdQqt3-PRAGRvwdw
http://www.google.com/url?q=http%3A%2F%2Fwww.pbs.org%2Fwgbh%2Fevolution%2Flibrary%2F01%2F4%2Fpdf%2Fl_014_02.pdf&sa=D&sntz=1&usg=AFQjCNGIz2SurRY9ecDdQqt3-PRAGRvwdw
http://www.google.com/url?q=http%3A%2F%2Fwww.enchantedlearning.com%2Fsubjects%2Fmammals%2Fmarsupial%2FBandicootprintout.shtml&sa=D&sntz=1&usg=AFQjCNG2cLAb78qFwP-_QfMa9dzu6xhGGw