Clicking a link still to hard for you?
Very well. In straight genetic terms, the general vertebrate rate of gain vs. loss in duplicated genes is 50%. That is, when any given gene is duplicated, just about half will develop functional divergence and become new genes with novel gene functions, while half will remain nonfunctional pseudogenes and are quickly lost. This rate varies due to a variety of factors (Sergei Rodin, for instance, has shown how this rate of retention is higher in organisms that have cytosine methylation (H. sapiens, M. musculus, and A. thaliana) than in organisms that do not have methylated genomes (S. cerevisiae, D. melanogaster, and C. elegans), and that epigenetic silencing also increases the rate of genes that develop functional divergence and are therefore kept).
What does that mean in actual organisms? Here's an example - Atsushi Ogura, Kazuho Ikeo, and Takashi Gojobori, when examining the gene loss rate of the gene set the original LCA of bilateria that led to the evolution of the eye, found that organisms with a compound eye showed more of gene loss rate in that set (29.9%, 24.5%, and 23.7% were lost in nematodes, mosquitoes, and flies, respectively) than organisms with a camera eye (12.8%–14.1% in vertebrates). In other words, humans lost less than 15% of the original LCA gene set during evolution, 852 genes out of the original 1019, and thanks to the retention rate of functionally divergent duplicate genes, during the evolutionary process the genome that became the human genome added a whole lot more genes for the eye (there are currently 13,303 known Expressed Sequence Tags for the human eye that code for proteins).
Happy now?
What, specifically, are you referring to? I don't remember bringing up placental mammal evolution vis a vis marsupial evolution, though I do recall correcting your misreading of a paper on the evolution of the ear in placentals and marsupials.