Bartonian extinctions

Lithornithidae is an extinct, possibly paraphyletic (but see below) group of early paleognath birds. They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous representatives. All are extinct today; the youngest specimen is the currently unnamed SGPIMH MEV1 specimen from the mid-Eocene Messel Pit site.

Lithornis is a genus of extinct paleognathous birds. Although Lithornis was able to fly well, their closest relatives are the extant tinamous (which are poor flyers) and ratites (which are flightless birds).

Pseudoprotoceras is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to central North America. It lived during the Late Eocene 37.2—33.9 Ma, existing for approximately . Pseudoprotoceras resembled hornless deer, but were more closely related to camelids.