It wont work, we would need to serialize not only DescriptorProtos.DescriptorProto but entire DescriptorProtos.FileDescriptorProto and then find corresponding DescriptorProtos.DescriptorProto by name. 

I think we could recreate the Protobuf descriptor from Parquet Schema. We need keep original field number for each protobuffer field.
Could we add field "int originalIndex" to parquet.schema.Type @julienledem? I guess it could be usefull also for other frameworks (Thrift).