The fixity of species is a Darwinian myth. We have seen species that don’t follow the rules of biologists and have hybrid animals, for instance the ligers, geeps (goats and sheep) are obviously a mystery for Darwinian evolution, but they fit in well with the Genesis-based creation model.
Sheep and goats belong to the same Genesis kind, which is a much wider concept than the biological term species. Sheep and goats actually belong to the same biblical kind, just like dogs and wolves make up one kind.
Now, 3o years ago an Inuit man in west Greenland shot a trio of strange cetaceans, with front fins like belugas and tails like narwhals.
He saved one of the skulls, hanging it on the outside of his shed.
A few years later, a scientist visiting the area spotted the skull and ended up taking it to the Natural History Museum of Denmark. It was a strange specimen: larger than either a skull from a beluga or narwhal whale, but with teeth that looked somehow between the two.
And genetic data on narwhals and belugas suggests that the two species diverged "5 million years ago" and haven't hybridized in any noticeable numbers for at least 1.25 million years.
Pappas, Stephanie. 2019. First-Ever Beluga-Narwhal Hybrid Found in the Arctic. Live Science (20 June).