Eremopezus
| Eremopezus Temporal range: Late Eocene 36–33 Ma |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Subclass: | Neornithes |
| Infraclass: | Paleognathae |
| Family: |
†Eremopezidae Rothschild, 1911 |
| Genus: |
†Eremopezus Andrews, 1904 |
| Species: | †E. eocaenus |
| Binomial name | |
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Eremopezus eocaenus Andrews, 1904 |
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| Synonyms | |
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Eremopezus is a prehistoric bird genus, possibly a palaeognath. It is known only from the fossil remains of a single species, the huge and presumably flightless Eremopezus eocaenus. This was found in Upper Eocene Jebel Qatrani Formation deposits around the Qasr el Sagha escarpment, north of the Birket Qarun lake near Faiyum in Egypt. The rocks its fossils occur in were deposited in the Priabonian, with the oldest dating back to about 36 million years ago (Ma) and the youngest not less than about 33 Ma.
It is not precisely known from which strata the first few remains of this bird were collected. They were formerly considered of Early Oligocene age—some 33-30 Ma—but this is now assumed incorrect, as only the upper and not the entire Jebel Qatrani Formation is of Oligocene age. It is also possible that they are from the slightly older Qasr el Sagha Formation, but as both this and the Oligocene parts of the Jebel Qatrani Formation were laid down in an ecosystem markedly different from that of the Eocene Jebel Qatrani Formation, it is now assumed that all material of E. eocaenus is from the lowest rocks of the Jebel Qatrani Formation.
It was originally described from a distal left tibiotarsus piece (specimen BMNH A843); a toe phalanx bone found soon thereafter was tentatively assigned to this bird. Eremopezus was initially believed a ratite and loosely allied with the elephant birds of Madagascar. Thus, when a piece of tarsometatarsus shaft was found some time later north of the ruins of Dimeh (Dimê; itself a bit north of the Birket Qarun) this was described as Stromeria fajumensis; though it had a size to match the holotype tibiotarsus it was thought to resemble an elephant bird even more. The shaft (specimen BSPG 1914 I 53) has a prominent plantar (backside) ridge also found in Mullerornis betsilei, and this was used to ally the fossil bone with this rather small and gracile elephant bird. The Eremopezus specimen on the other hand has deep ligamental pits on the lateral and medial sides of the distal condyles, which are not found in the elephant birds proper. These pits together with a crisply defined ridge held a sling of ligament, which in turn—in place of the bony supratendinal bridge found in some other birds—kept the ankle tendons from dislocating. The tarsometatarsus is also more similar to that of an unspecific ratite, such as an emu, ostrich or rhea, rather than to the apomorphic one of the elephant birds.
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