They are known from fossils dating to the Upper Paleocene through the Middle Eocene of North America and Europe, with possible Late Cretaceous representatives.

They possessed a rhynchokinetic skull with relatively unfused cranial bones, a weakly fused pygostyle and a splenial.

[11] Unlike modern tinamous, at least Lithornis has toe claws and reversed halluxes that allow for efficient perching.

[1] Also unlike modern tinamous most lithornithids were capable flyers, with their wings and sterna comparable to those of storks and vultures[12] some even able to perform long distance migrations.

[17] Lithornithids, much like modern paleognaths, ibises and shorebirds, had a vibrotactile bill tip organ, suggesting the development of this feature in the Cretaceous.