Eleutherornis
{{Short description|Extinct genus of birds}}
{{Speciesbox
| fossil_range = {{fossil_range|Lutetian}}
| image = Eleutherornis.png
| image_caption = E. cotei material from Switzerland
| display_parents = 2
| grandparent_authority = Wetmore, 1951
| taxon = Eleutherornis cotei
| parent_authority = Schaub, 1940
| authority = (Gaillard, 1936)
| synonyms = *Diatryma cotei Gaillard 1936
- Eleutherornis helveticus Schaub 1940
}}
Eleutherornis cotei is an extinct flightless predatory cariamiform bird which lived during the Middle Eocene of France and Switzerland. Since the early 20th century, researchers have initially described the fossils of Eleutherornis as separate taxa, some remains as a species of Gastornis and others as an ancient ratite related to modern ostriches. However, subsequent analyses have questioned the original interpretations, and a thorough reexamination in 2013 indicated that all of these described remains represent the same species.
It is estimated that Eleutherornis is a relatively tall bird that could grow up to {{convert|1.5|m|ft}} in total height. Paleontologists now agree that Eleutherornis certainly belongs to the order Cariamiformes, which includes the modern seriemas and the extinct Phorusrhacidae, a group of flightless predatory birds mainly known from the Americas. This makes Eleutherornis a relative of the phorusrhacids, with some researchers even suggesting that Eleutherornis is a European member of this group, though this claim has been disputed by others and additional material may be required for confirmation.
History of discovery
File:Eleutherornis find locations.png
The phalanges of Eleutherornis was first reported from Switzerland in Egerkingen by Schaub back in 1929, but he only classified them as Aves incertae sedis.{{cite journal|author=Schaub S|year=1929|title=Über eocäne Ratitenrste in der osteologischen Sammlung des Basler Museums|journal=Verhandlungen Naturforschenden Gesllschaft Basel|volume=40|pages=588–598}} From 1936 to 1937, Gaillard described the current type specimen of this taxon from France near Listeu, a municipality of the metropolis of Lyon, under the binomial name Diatryma cotei as a possible species of Gastornis (formerly Diatryma), and suggested that the phalanges reported by Schaub in 1929 resembles this species.{{cite journal|author=Gaillard, C.|year=1936|title=Un oiseau géant dans les dépôts éocènes du Mont-d'Or lyonnais|journal=Comptes Rendus de l'Académie des Sciences|volume=202|pages=965–967}}{{cite journal|author=Gaillard, C.|year=1937|title=Un oiseau géant dans les dépôts éocènes du Mont-d'Or lyonnais|journal=Annales de la Société Linnéenne de Lyon|volume=80|pages=111–126}} In 1940, Schaub named Eleutherornis helveticus based on bird fossils from Switzerland which he considered as a ratite.{{cite journal|author=Schaub, S.|year=1940|title=Ein Ratitenbecken aus dem Bohnerz von Egerkingen|journal=Eclogae Geologicae Helvetiae|volume=33|pages=274–284}} In 1951, Wetmore placed Eleutherornis within its own family Eleutherornithidae under the order Struthioniformes,{{cite journal|author=Wetmore, A.|year=1951|title=A revised classification for the birds of the world|journal=Smithsonian Miscellaneous Collections|volume=117|issue=4|pages=1–22|url=https://repository.si.edu/bitstream/handle/10088/23764/1952%20vol117%20wetmore%20birds%20of%20world%201-22.pdf}} and the other putative ratite Proceriavis martini was also tentatively placed as a member of this family in 1979.{{cite book|author1=Harrison, C.J.O.|author2=Walker. C.A.|year=1979|chapter=Birds of the British Lower Oligocene|title=Studies in Tertiary avian paleontology|publisher=Tertiary Research Special Paper|volume=5|pages=29–43}}
Subsequent analyses questioned the original interpretations, with D.? cotei considered as Aves incertae sedis outside the genus Gastornis, and with E. helveticus considered as a non-struthiform and a possible phorusrhacid instead.{{cite book|author=Olson, Storrs L.|year=1985|chapter=The Fossil Record of Birds|title=Avian Biology|pages=79–238|publisher=Academic Press|chapter-url=https://repository.si.edu/bitstream/handle/10088/6553/VZ_167_Fossil_Record_of_Birds.pdf}}{{cite book|author=Mlikovsky, J.|year=2002|title=Cenozoic Birds of the World Part 1: Europe|publisher=NINOX Press|location=Praha|url=https://www.biologicaldiversity.org/campaigns/global_owl_project/descriptions/Fossil_owls/Mlikovski%202002%20Cenozoic%20birds%20of%20the%20world.pdf}} In 2009, the German paleontologist Gerald Mayr suggested that both D? cotei and E. helveticus are neognaths and they possibly belong the same clade, while considering the putative ratite affinities of Proceriavis to be uncertain.{{cite book|author=Mayr, G.|year=2009|chapter=Palaeognathous Birds|title=Paleogene Fossil Birds|publisher=Springer Cham|pages=25–33|isbn=978-3540896272|url=https://zarmesh.com/wp-content/uploads/2022/03/Paleogene-Fossil-Birds.pdf}} This was confirmed through the reexaminations and comparisons of the specimens by Angst and colleagues in 2013, who considered both D.? cotei and E. helveticus to represent the same species based on virtually identical material and recombined the name of the taxon as Eleutherornis cotei.{{Cite journal | doi = 10.1371/journal.pone.0080357| title = "Terror Birds" (Phorusrhacidae) from the Eocene of Europe Imply Trans-Tethys Dispersal| journal = PLOS ONE| volume = 8| issue = 11| pages = e80357| year = 2013| last1 = Angst | first1 = D. | last2 = Buffetaut | first2 = E. | last3 = Lécuyer | first3 = C. | last4 = Amiot | first4 = R. | pmid=24312212 | pmc=3842325| bibcode = 2013PLoSO...880357A| doi-access = free}}
Description
Eleutherornis is the last known giant bird of Europe during the Paleogene,{{cite journal|vauthors=Pérez-Pueyo M, Cruzado-Caballero P, Moreno-Azanza M, Vila B, Castanera D, Gasca JM, Puértolas-Pascual E, Bádenas B, Canudo JI|year=2021|title=First record of a giant bird (Ornithuromorpha) from the uppermost Maastrichtian of the Southern Pyrenees, northeast Spain|journal=Journal of Vertebrate Paleontology|volume=41|issue=1|pages=e1900210|doi=10.1080/02724634.2021.1900210|bibcode=2021JVPal..41E0210P |s2cid=235506488}} which stood up to {{convert|1.5|m|ft}} tall, roughly around the size of Patagornis. Its specimens show a combination of basal and derivative characters. Tarchlea of tarsometatarsus II is enlarged in its middle part as in psilopterines, while the pre-acetabulary of the ilium is more compressed laterally and more ventilated with neural spines of the synsacral vertebrae than in psilopterines, and thus recalls the more evolved phorusrhacids. Ungual phalanges are less compressed laterally and have a more developed flexor tubercle than those of the other cariamiform bird, Strigogyps.
Classification
Angst and colleagues suggested that Eleutherornis is potentially the only known phorusrhacid in Europe and one of the few possible members of this family outside the Americas along with Lavocatavis.{{Cite journal |last1=Mourer-Chauviré |first1=Cécile |last2=Tabuce |first2=Rodolphe |last3=Mahboubi |first3=M’hammed |last4=Adaci |first4=Mohammed |last5=Bensalah |first5=Mustapha |date=2011-08-28 |title=A Phororhacoid bird from the Eocene of Africa |url=https://doi.org/10.1007/s00114-011-0829-5 |journal=Naturwissenschaften |language=en |volume=98 |issue=10 |pages=815–823 |doi=10.1007/s00114-011-0829-5 |pmid=21874523 |bibcode=2011NW.....98..815M |s2cid=19805809 |issn=1432-1904|url-access=subscription }} Gerald Mayr suggested that Eleutherornis more closely resembles other cariamiforms Strigogyps and ?Dynamopterus anthracinus, while Lavocatavis is likely more related to a possible paleognath Eremopezus, questioning the taxonomic placement of both taxa as phorusrhacids.{{cite book|author=Mayr, G.|year=2017|chapter=Cariamiforms and Diurnal Birds of Prey|title=Avian Evolution: The Fossil Record of Birds and its Paleobiological Significance|pages=189–204|publisher=Wiley-Blackwell|location=Chichester|isbn=978-1119020769}}{{cite journal|author=Mayr, G.|year=2020|title=An updated review of the middle Eocene avifauna from the Geiseltal (Germany), with comments on the unusual taphonomy of some bird remains|journal=Geobios|volume=62|pages=45–59|doi=10.1016/j.geobios.2020.06.011|bibcode=2020Geobi..62...45M }} Buffetaut and Angst, who previously assigned this taxon to phorusrhacids, criticized Mayr's classification in 2021 for his claim not being based on substantial morphological evidence, and that Eleutherornis is likely Phorusrhacidae incertae sedis.{{Cite journal |last1=Buffetaut |first1=Eric |last2=Angst |first2=Delphine |date=June 2021 |title=Macrornis tanaupus Seeley, 1866: an enigmatic giant bird from the upper Eocene of England |url=https://www.cambridge.org/core/product/identifier/S0016756820001466/type/journal_article |journal=Geological Magazine |language=en |volume=158 |issue=6 |pages=1129–1134 |doi=10.1017/S0016756820001466 |bibcode=2021GeoM..158.1129B |issn=0016-7568|url-access=subscription }}
Because the known fossils are fragmentary, definitive phylogenetic classification cannot be conducted, and Mayr still suggested that it is likely closer to Strigogyps in 2022, based on a biogeographical viewpoint and a morphological similarity of the tarsometatarsus and curved ungual phalanges from both taxa.{{cite book|author=Mayr, G.|year=2022|chapter=Accipitriformes (New World Vultures, Hawks, and Allies), Falconiformes (Falcons), and Cariamiformes (Seriemas and Allies)|title=Paleogene Fossil Birds|series=Fascinating Life Sciences |edition=2nd|publisher=Springer Cham|pages=153–176|doi=10.1007/978-3-030-87645-6_8|isbn=978-3-030-87644-9 }} While tentatively classified as a phorusrhacid in their 2024 study, LaBarge, Garderner and Organ excluded both Eleutherornis and Lavocatavis from phylogenetic analysis and considered their identity as phorusrhacids highly questionable.{{cite journal |last1=LaBarge |first1=T. W. |last2=Gardner |first2=J. D. |last3=Organ |first3=C. L. |year=2024 |title=The evolution and ecology of gigantism in terror birds (Aves, Phorusrhacidae) |journal=Proceedings of the Royal Society B: Biological Sciences |volume=291 |issue=2021 |at=20240235 |doi=10.1098/rspb.2024.0235 |pmid=38654650 |pmc=11040249 }} [https://rs.figshare.com/articles/journal_contribution/S1_Text_from_The_evolution_and_ecology_of_gigantism_in_terror_birds_Aves_Phorusrhacidae_/25546651?backTo=/collections/Supplementary_material_from_The_evolution_and_ecology_of_gigantism_in_terror_birds_Aves_Phorusrhacidae_/7165777 Supplementary Information]
References
{{Reflist}}
{{Cariamiformes|C.|state=collapsed}}
{{Taxonbar|from=Q15616450}}