The Fallacy of the Horizontal Transitional Species
Otherwise known as the fallacy of jumping from bough to bough in the tree of life without climbing down one branch and climbing up the other, the Horizontal Transitional Species Fallacy is one of the most frequently repeated errors in much of Creationism's internet presence. How many times do we see demands from Creationists to see "one kind giving birth to another kind". They demand to see a dog turn into a cat, or a cow turn into a whale, or even a crocodile turn into a duck - Kirk Cameron and Ray Comfort's famous Crocoduck, which is what they imagined we would have to produce if evolution was a valid theory. So bizarre was this claim that famed Internet YouTuber Potholer54 (Peter Hadfield), actually hosted the Golden Crocoduck Awards (2008 - 2013) for the most outlandish Creationist claims of what evolution is about.
In spite of the efforts of almost every supporter of evolutionary biology who participates in various internet venues like Facebook and YouTube, Creationists continue to push this fallacy, for two reasons, I believe. First is that it is an easy shot - "Show me a cat giving birth to a dog!" - just a few short words, and their base is energized. Second, it makes those of us on the side of rational thought stop, shake our heads and ask ourselves "Do we really want to go through this AGAIN?".