This technology includes a novel capsid protein for recombinant adeno-associated virus (AAV)-mediated gene transfer evaluation. We have identified a "fossilized" endogenous AAV sequence element (referred to as mAAV-EVE) within the germline of an ancient lineage of Australian marsupials and have cloned and sequenced mAAV-EVE orthologs from at least fifteen lineage-specific taxa. Using computational analysis of mAAV-EVE sequence alignments, we have inferred the coat protein sequence of a >25-million-year-old adeno-associated virus which circulated among host species sometime during the Eocene-Oligocene transition. This novel AAV coat protein sequence may provide the basis for recombinant AAV vectors with unique biological properties. Moreover, the method of derivation of the ancient marsupial AAV coat protein sequence may be used for any endogenous AAV sequences occurring within related taxa in sufficient number.