One set of drawings from the 19th century is a fraud. We have other drawings and we have plenty of real-life photographs now.
All embryos have throwbacks to their evolutionary history. This is entirely different from saying that mammals actually -become- reptiles at one point in their development.
Sometimes there's only one solution to a particular scaffolding problem ~ you could conceivably have a line of mammals descended directly from fish without the amphibian/reptile stuff (with some clever use of recombinant DNA technology, of course), and you'd probably end up with a developmental scheme pretty much like the one you see being exercised by mammals today.