Which type of organism first appeared during the mesozoic era?
primates
cyanobacteria
marsupial mammals
jawless fish
during which time period would the platypus have evolved?
mesozoic era
cambrian explosion
quaternary period
tertiary period

The first one I think is jawless fish because I found stuff on an eel-like creature from that time. Also marsupials and primates are from much further along the line while according to science we were WAY past bacteria being the only beings at this point:) and the second, I would say Quaternary period because that is the one we are in today (unless I read that wrong) and I have never heard of a platypus hanging out with a mastadon or something:P Hope that helps:)

Bhope this : )