I don't think there's a reason to believe that the source and destination lifeforms of a panspermia event should appear to be related in any way. They may be biochemically similar initially, but selection pressures in their environments over the subsequent (M/B)illions of years would drive dramatic divergence.
Maybe the only possible way to even guess that they may be related would be to sequence the genome of (recently living or miraculously preserved) samples from both populations to search for similarities left over from their common ancestor. These could be vestigial genes that are not expressed, but still exist in the genotype of every known living thing. Until that happens, we can't do anything but speculate.
Maybe the only possible way to even guess that they may be related would be to sequence the genome of (recently living or miraculously preserved) samples from both populations to search for similarities left over from their common ancestor. These could be vestigial genes that are not expressed, but still exist in the genotype of every known living thing. Until that happens, we can't do anything but speculate.
