Enigmatic vertebrate taxa

Westlothiana ("animal from West Lothian") is a genus of reptile-like tetrapods that lived about 341 million years ago during the latest part of the Viséan age of the Carboniferous. The genus is known from a single species, Westlothiana lizziae. It is the oldest known uncontroversial tetrapod, closely related to but not an amniote.

Casineria is an extinct genus of tetrapod which lived about 340–334 million years ago in the Mississippian epoch of the Carboniferous period. Its generic name, Casineria, is a latinization of Cheese Bay, the site near Edinburgh, Scotland, where the holotype fossil was found. When originally described in 1999, it was identified as a transitional fossil noted for its mix of basal (amphibian-like) and advanced (reptile-like) characteristics, putting it at or very near the origin of the amniotes, the group containing all mammals, birds, modern reptiles, and other descendants of their reptile-like