Young-earth creationists believe that all life, living and fossil, can be grouped into a series of families – they call them baramins, a made-up Hebrew word for “created kinds” – which all existed together at the same time from the very beginning. They use this completely artificial understanding of our planet’s biosphere in generating their concept of a “missing link”: in order for something to be a “true” transitional form under their model, it would have to be something halfway between two separate created “kinds”. Because they automatically assign every species to a particular created kind and only to that created kind, their “transitional form” is something that could never exist.
The usual parodies of evolutionary transitional fossils, like Ray Comfort’s infamous crocoduck, are openly tongue-in-cheek. But because creationists see all animals as belonging to individual, immutable kinds, they represent evolution as “change from one ‘kind’ to another” claiming that evolution predicts we should see transitions between their “created kinds”: for example, a fossil that is midway between a dog and a cat. Just as with living species, all fossil species are placed within strict “created kinds”, allowing creationists to maintain the illusion that nothing is ever “in-between”.This is only one aspect of the problem. The other problem, mentioned in Young's third post in the series, is the mistaken belief that evolution is entirely vertical and that there is only direct ancestry and not collateral ancestry. With this understanding, one species directly leads to another species and so on. That Archaeopteryx may not have been ancestral to modern birds must mean that we have a gap in the fossil record. These “gaps” must mean that there are problems with evolutionary biology. With created “kinds,” the species related to Archaeopteryx simply create gaps of their own. It is difficult to penetrate this logic.