Lithornithiformes

Lithornithidae is an extinct, possibly paraphyleticPaleogene Fossil Birds
/ref> (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.

Lithornithids had long, slender, bills for probing. They closely resembled modern tinamous, aside from more developed wings. They possessed a rhynchokinetic skull with relatively unfused cranial bones, a weakly fused pygostyle and a splenial. The unguals were more curved than in tinamous and probably allowed better perching in trees.

The order Lithornithiformes was erected by Dr. Peter Houde in 1988. Initially, only three genera ('' Lithornis'', '' Paracathartes'', and '' Pseudocrypturus'') and eight named species were included. '' Promusophaga'' (Harrison & Walker, 1977) originally considered a stem- turaco, is considered synonymous with '' Lithornis vulturinus''. '' Fissuravis'' may also belong to the clade, and several unnamed remains are known.

Taxonomy

Lithornithiformes Houde, 1988Mikko's Phylogeny Archiv


*†Lithornithidae Houde, 1988 (False tinamous)
**†'' Calciavis grandei'' Nesbitt, 2016
**†'' Fissuravis weigelti'' Mayr, 2007
**†'' Paracathartes howardae'' Harrison, 1979 (Early Eocene of WC US)
**†'' Pseudocrypturus cercanaxius'' Houde, 1988
**†'' Lithornis'' Owen, 1840 Promusophaga'' Harrison & Walker, 1977; ''Pediorallus">' Promusophaga'' Harrison & Walker, 1977; ''Pediorallus'' Harrison, 1984; ''Parvigyps'' Harrison & Walke,r 1977] (Paleocene – Early Eocene)
***†''Lithornis celetius, L. celetius'' Houde, 1988
***†''Lithornis plebius, L. plebius'' Houde, 1988
***†'' L. promiscuus'' Houde, 1988
***†'' L. nasi'' (Harrison, 1984) Houde, 1988 'Pediorallus nasi'' Harrison, 1984">Pediorallus_nasi.html" ;"title="' 'Pediorallus nasi'' Harrison, 1984***†''Lithornis hookeri">L. hookeri'' (Harrison, 1984) Houde, 1988 [''Pediorallus hookeri">Pediorallus nasi">'Pediorallus nasi'' Harrison, 1984***†''Lithornis hookeri">L. hookeri'' (Harrison, 1984) Houde, 1988 [''Pediorallus hookeri'' Harrison, 1984]
***†''Lithornis vulturinus, L. vulturinus'' Owen, 1840 [''Parvigyps praecox'' Harrison & Walker, 1977; ''Promusophaga magnifica'' Harrison & Walker, 1977; '' Pediorallus barbarae'' Harrison & Walker, 1977a] (London Clay Early Eocene of England)

Several studies have shown conflicting status on the monophyly of the group. Some studies recover them as a paraphyletic assemblage leading to modern paleognaths, but more recent examinations group them in a single, natural group basal to the rest of Palaeognathae. Of issue is '' Paracathartes'', which differs radically from other lithornithids and has been suggested to be more closely related to extant paleognaths,Houde, Peter W. (1988). "Paleognathous Birds from the Early Tertiary of the Northern Hemisphere". Publications of the Nuttall Ornithological Club (Cambridge, MA) though it is recently recovered as a derived lithornithid.

'' Lithornis'' itself may be paraphyletic in relation to '' Paracathartes'' and '' Pseudocrypturus''.

Paleobiology

In a study about ratite endocasts, ''Lithornis'' ranks among the taxa with well developed olfactory lobes. This is consistent with a nocturnal, forest-dwelling lifestyle, though as much all volant birds it retains large optical lobes.

Unlike modern tinamous, at least '' Lithornis'' has toe claws and reversed halluxes that allow for efficient perching. Also unlike modern tinamous most lithornithids were capable flyers, with their wings and sterna comparable to those of storks and vultures some even able to perform long distance migrations. The exception is '' Paracathartes'' which was similar to modern tinamous and fowl in its sternum and wing proportions and likely was a burst flyer as well.

Several egg fossils have been attributed to lithornithid birds. Both '' Lithornis'' and '' Paracathartes'' have entire nests assigned to them. Their eggshells are, perhaps unsurprisingly, noted as being "ratite-like".

Studies on lithornithid feathers shows that some species had gloss similar to that of cassowaries.

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

Notes

References

External links

* Christa Lesté-Lasserre
Bird beak extra sense evolved more than 70 million years ago
on: NewScientist, 2 December 2020

{{Taxonbar, from=Q19169

Notopalaeognathae
Paleogene birds of Europe
Bartonian extinctions
Paleogene birds of North America
Prehistoric bird families