Pristochampsids made the Ark!
The Ark Encounter list includes both Pristochampsidae and Planocraniidae as Ark Kinds. This is interesting because those are two different names for the same family. I can’t find any modern scientists arguing that those are two separate families. The only argument is over which name should be used.
Planocraniids are an extinct family of animals commonly referred to as “hoofed crocodiles”. As you can probably guess by that name, they were similar to modern crocodiles, except that they were adapted for life on land. One of those adaptations was nails formed into hoof-like structures to help them walk on land, which modern crocodilians are not very good at. They also had more vertical heads, presumably because they didn’t need to lie hidden at the surface of the water to ambush prey.
The family was first named in 1831, when a scientist named Gray published a paper describing Pristichampsus rollinati, which he assigned to a new family Pristochampsidae. However, he didn’t have much to base it on, because the remains he was describing included only some teeth and bone fragments. Since then, more members of this family have been found.
In 2013, C. A. Brochu re-examined the specimens and concluded that the specimens Gray had were not sufficient to define a new species. Thus, he concluded that the name Pristochampsidae was invalid. The section in his paper describing the consequences of this conclusion is unusually hyperbolic for a scientific paper:
“I do not say this lightly; Pristichampsus is widely used. Its elimination may lead to confusion in the literature and, in all likelihood, my own violent death at the hands of my colleagues. Taxonomic stability should be promoted, and I would rather not be killed. The ideal solution would be the discovery of a more complete and diagnosable specimen from Argenton that can serve as a neotype. In the absence of such material, we are obliged to set the name aside.”
I have not followed up to determine if Brochu was later murdered by overly passionate paleontologists.
Anyway, he concluded that the correct name for the family is Planocraniidae. That’s because in 1976 another genus, Planocrania, was originally assigned to its own family, Planocranidae, before it was moved into Pristochampsidae. Thus, Planocranidae was the first valid name assigned to a member of this family, and thus, by scientific naming conventions, it is the correct name. However, Brochu also noted that Planocranidae would not be the correct spelling in Latin, and adjusted the family name to the correct spelling, Planocraniidae.
This is particularly interesting because the spelling on the Ark Encounter list is Planocraniidae. This implies that whatever their source material was, it could not simply date back to a time when Planocrania was assigned to its own family, because the spelling at that time was Planocranidae. There has never been a time when Planocraniidae, with the double “i”, co-existed with a separate family called Pristochampsidae. By the time the paper that officially adjusted the spelling existed, it had been settled for decades that all of these animals belonged in the same family. The only argument has been what to call it. So how did both names wind up on the Ark Encounter list?