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The article says that previous studies of ostrich embryos didn't show the five digits because the embryos were too far along in development and the other two digits had disappeared.

How do we know that the same thing didn't happened with the dinosaurs? I know we have some fossilized embryos and eggs, but if it took them this long to find the differences in ostrich embryo stages, how can they say that dinosaurs also didn't do this?

"When we look closely at the universe, we see the hand of God. Likewise, when we view the complex underlying structure and chemistry of life, indications of... God's work---are unmistakable. Scientists, only a few decades ago, were confident that they would soon crack the mystery of life, and would very likely be able to "create" life in test tubes, using only raw chemicals. But the mechanics of life soon proved beyond the most clever of scientists. Sir Francis Crick has noted that the "origin of life seems almost to be a miracle, so many are the difficulties in its occurring." Another scholar, Klaus Dose, says that the solutions to the difficulties in origin-of-life research are "beyond our imagination."

How do we know that the same thing didn't happened with the dinosaurs? I know we have some fossilized embryos and eggs, but if it took them this long to find the differences in ostrich embryo stages, how can they say that dinosaurs also didn't do this?

You are too logical. Of course, that is what one would think. The problem is, I believe, that the opposite was asserted prior to this. IOW what was assumed about dinosaur fingers cannot be true.

Bird metacarpal homology

Hinchliffe attempts to demonstrate, using two different lines of embryological evidence, that the digits of the avain carpometacarpus are II-III-IV, then proceeds to use this as evidence that birds are not derived dinosaurs.

The latter point strikes me as weak, since he is using embryological evidence to dispell the homologies posited by workers who are looking only at osteological evidence, while a priori accepting the homolgies these workers postulate for another group. On the other hand, part of the point of the paper is that homologies established on osteological evidence may be weaker than is often thought. In any case, if one were to accept Dr. Henchliffe's findings at face value, most parsimoniously it would simply cause us to reconsider the homologies of the theropod manus (translation: if birds' digits are II-III-IV, given the evidence, isn't it just a simpler conclusion that dinosaurs' digits were II-III-IV?).

The same would happen if, for instance, it was discovered that the little toe of the horse became the single hoof.

You should also understand that Dr. Alan Feduccia is a severe critic of the now orthodox bird-dino connection.

The article says that previous studies of ostrich embryos didn't show the five digits because the embryos were too far along in development and the other two digits had disappeared.

How do we know that the same thing didn't happened with the dinosaurs?

Good point. Evidence from late-stage dinosaur embryos will have to be added to the equation. Right now, this doesn't "confirm" anything.