library_construction_protocol: Dunnart joeys were removed from the pouch and sacrificed by decapitation. Both hemispheres of the neocortex were micro-dissected out, transferred into TRIzol reagent (ThermoFisher), homogenized using 23- and 27-gauge needles and total RNA extracted using the standard TRIzol protocol. The RNA pellet was resuspended in RNase-free water, treated with DNaseI (Qiagen) and column-purified with a RNeasy Minelute kit (#74204, Qiagen). All dunnart RNA samples showed a RNA integrity number (RIN) of 8.6 or higher on a Bioanalyzer 2100 RNA Nano assay (Agilent). 400 ng of total RNA from each dunnart sample was used for cDNA library preparation. RNA samples were depleted of cytoplasmic and mitochondrial ribosomal RNA using Ribo-Zero (#15065382, Illumina) then fragmented. A Truseq Stranded Total RNA kit v4 (#15031048, Illumina) was then used to perform first- and second-strand cDNA synthesis, followed by adapter ligation and PCR amplification of the cDNA products, as per the standard low sample (LS) protocol.