Lithornithidae is an extinct, possibly paraphyleticPaleogene Fossil Birds
/ref> (but see below) group of early

paleognath Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the class Aves of the clade Archosauria. It is one of the two extant infraclasses of birds, the other being Neognathae, both of which form Neornithes. Palaeognathae contain ...

birds. They are known from fossils dating to the Upper

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

through the

Middle Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "da ...

of North America and Europe, with possible

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

representatives. All are extinct today; the youngest specimen is the currently unnamed SGPIMH MEV1 specimen from the mid-Eocene

Messel Pit The Messel pit (german: Grube Messel) is a disused quarry near the village of Messel (Landkreis Darmstadt-Dieburg, Hesse) about southeast of Frankfurt am Main, Germany. Bituminous shale was mined there. Because of its abundance of well-preserved ...

site. Lithornithids had long, slender, bills for probing. They closely resembled modern

tinamou Tinamous () form an order of birds called Tinamiformes (), comprising a single family called Tinamidae (), divided into two distinct subfamilies, containing 46 species found in Mexico, Central America, and South America. The word "tinamou" come ...

s. They possessed a rhynchokinetic skull with relatively unfused cranial bones, a weakly fused

pygostyle Pygostyle describes a skeletal condition in which the final few caudal vertebrae are fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these. The pygostyle is the main compone ...

and a

splenial The splenial is a small bone in the lower jaw of reptiles, amphibians and birds, usually located on the lingual side (closest to the tongue) between the angular and surangular The suprangular or surangular is a jaw bone found in most land ver ...

. The

ungual An ungual (from Latin ''unguis'', i.e. ''nail'') is a highly modified distal toe bone which ends in a hoof, claw, or nail. Elephants and ungulates have ungual phalanges, as did the sauropod Sauropoda (), whose members are known as sauropods (; ...

s 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 The turacos make up the bird family Musophagidae ( "banana-eaters"), which includes plantain-eaters and go-away-birds. In southern Africa both turacos and go-away-birds are commonly known as loeries. They are semi-zygodactylous: the fourth ( ...

, 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.html" ;"title="' 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. promiscuous'' Houde, 1988 ***†'' L. nasi'' (Harrison, 1984) Houde, 1988 'Pediorallus_nasi''_Harrison,_1984.html" ;"title="Pediorallus_nasi.html" ;"title="' 'Pediorallus_nasi''_Harrison,_1984">Pediorallus_nasi.html"_;"title="'Pediorallus_nasi">'Pediorallus_nasi''_Harrison,_1984***†''Lithornis_hookeri.html" ;"title="Pediorallus nasi">'Pediorallus nasi'' Harrison, 1984">Pediorallus_nasi.html" ;"title="'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 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. 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 Paleognathae Paleogene birds of Europe Bartonian extinctions Paleogene birds of North America Prehistoric bird families