Product Code Database
Brontornis is an extinct genus of giant bird that inhabited Argentina during the Early Miocene to Middle Miocene. Its taxonomic position is highly controversial, with authors alternatively considering it to be a Cariamiformes, typically a phorusrhacid (terror bird) or an Anserimorphae.
Moreno's rival, Florentino Ameghino, also found fossils of Brontornis which he named Brontornis platyonyx in 1895 based on four pedal phalanges found at Monte Leon. The species has been synonymized with Brontornis. Ameghino also named Liornis floweri based on a distal tibiotarsus, distal tarsometatarsus, and two pedal phalanges of a juvenile that was synonymized with Brontornis in 1967.Buffetaut, E. (2016). A reassessment of the giant birds Liornis floweri Ameghino, 1895 and Callornis giganteus Ameghino, 1895, from the Santacrucian (late Early Miocene) of Argentina. Palaeovertebrata, 40, e3. Liornis minor was also synonymized in 1967, but it has since been synonymized with Phorusrhacos. Callornis giganteus, another Ameghino taxon, may also be a synonym of Brontornis or a distinct close relative. Recently, the affinities of some Brontornis specimens has come into question due to the uncertain and debated phylogenetic position of the genus and its synonyms.
Brontornis is a genus of birds (Aves), which is sometimes referred to its own family Brontornithidae. These are very large, flightless birds from the Miocene of South America and are known from very fragmentary material. The exact systematic assignment of Brontornis and the Brontornithidae is very uncertain and in a constant flux, which is largely due to the fragmentary nature of the remains. Originally placed on the base of the Phorusrhacidae ("terror birds"),Alvarenga, H. M., & Höfling, E. (2003). Systematic revision of the Phorusrhacidae (Aves: Ralliformes). Papéis Avulsos de Zoologia, 43(4), 55-91. there are several different views on its classification today. After several cladistic studies, the Brontornithidae have been found as basal geese relatives.Tambussi, C. P., & Degrange, F. J. (2013). Neogene Birds of South America. In South American and Antarctic Continental Cenozoic Birds (pp. 59-86). Springer, Dordrecht.Agnolin, F. (2007). Brontornis burmeisteri Moreno & Mercerat, un Anseriformes (Aves) gigante del Mioceno Medio de Patagonia, Argentina. Revista del museo argentino de ciencias naturales nueva serie, 9(1), 15-25. On the other hand, they also form the sister group of the Cariamiformes, which combine today's Seriema and the Phorusrhacidae. Since the introduction of the Brontornithidae as a family group, this has mostly been considered monogeneric or monospecific. Some authors have considered other genera as possible relatives, but most of these have been regarded as synonyms of Brontornis or Phorusrhacos. However, a Tibiotarsus of a large bird similar to Brontornis was found in Oligocene strata in Salla-Luribay, Bolivia, making it the oldest known Brontornithid fossil known.Buffetaut, E. (2017). A brontornithid from the Deseadan (Oligocene) of Bolivia. Contrib. Mus. Argent. Cienc. Nat, 7, 39-47.
Traditionally, Brontornis was usually attributed as a genus to the extinct family of the Phorusrhacidae ("Terror birds"), which was quite widespread in South America and comprises large to very large, mostly predatory birds. These are related to the seriama, sharing features such as a hook-shaped upper beak and the curved ungues, which had sharp claws and thus distinguish the birds as predatory carnivores. Within the Phorusrhacids, Brontornis was referred to their own subfamily of Brontornithinae, very large and massive birds which also included physical territories and paraphysis. The allocation to the Phorusrhacidae was mainly based on the strong lower jaw symphysis and the targeted Tarsometatatarsus at the front and back, and was supported by Herculano M. F. Alvarenga and Elizabeth Höfling in 2003. A revision of the genre of Federico L. Agnolin in 2007 rejects the assignment based on these characteristics to the Phorusrhacids, since they also occur in other early large running birds, for example in Odontoanserae or within the Dromornithidae. The rotation of the middle shape of the Tibiotarsus and the construction of the square leg suggest for a closer relationship with the goose family (aneriform) rather than Phorusrhacidae. For these reasons, Brontornis was excluded from the Phorusrhacids and moved to the base of the goose birds by Agnolin. Physornis and Paraphysornis, on the other hand, have been considered close relatives of Brontornis in their own subfamily in Phorusrhacidae, Brontornithinae,Acosta-Hospitalache, C., & Tambussi, C. (2005). Phorusrhacidae Psilopterinae (Aves) en la Formación Sarmiento de la localidad de Gran Hondonada (Eoceno Superior), Patagonia, Argentina. Spanish Journal of Palaeontology, 20(2), 127-132. though it is sometimes referred to as Physornithinae.Silva, L. G. D. (2020). Revisão sobre a biomecânica da família Phorusrhacidae.Tambussi, C. P., & Degrange, F. J. (2013). The Paleogene birds of South America. In South American and Antarctic Continental Cenozoic Birds (pp. 29-47). Springer, Dordrecht.
This phylogenetic position for Brontornis had originally been favored by the first descriptions of the genus, but Mathilde Dolgopol de Sáez classified it as a relative of geese and Gastornis in 1927.Buffetaut, E. (2014). Tertiary ground birds from Patagonia (Argentina) in the Tournouër collection of the Muséum National d’Histoire Naturelle, Paris. Bulletin de la Société géologique de France, 185(3), 207-214. Subsequently, after Agnolin's revision, his analysis was met with some approval from other paleontologists, but disagreements from other.Tambussi, C. P. (2011). Palaeoenvironmental and faunal inferences based on the avian fossil record of Patagonia and Pampa: what works and what does not. Biological Journal of the Linnean Society, 103(2), 458-474. Taken from
A phylogenetic analysis of Phorusrhacidae in 2011 again concluded that Brontornis was justified in the placement with the special expression of a fragmented thoracic vertebrae. Once again, suggesting that Brontornis sat within Anserimorpha.
With other cladist analyses suggested the structure of resemble that of Anserimorphs. The lack of the striking bone footbridge (Pons Supratendineus) on the front of the lower joint of the tibiotarsus of Brontornis was also pointed out several times, which in occurs in the Phorusrhacidae. Furthermore, the short and robust construction of the mandible contrasts to the long and slim mandibles of Phorusrhacids, again suggested that Brontornis isn't a phorusrhacid. According to the examinations already mentioned, the different design of the lower jaw also results in a different diet of Brontornis than Phorusrhacids.
However, a study from 2017 suggested that Brontornis belonged to sister taxon to Cariamiformes. As a result, the genus moved close to the Phorusrhacidae, but not directly in it. Suggesting that the previous study a misinterpreted the orientation of the tarsometatarsus as a central point of systematic assignment of Brontornis. It was pointed out that, the previous studies only used sparse material of Brontornis. However, a 2021 study once again found Brontornis to be a Gastornithiform.
Contrarily, some paleontologists have proposed an herbivorous diet for Brontornis. Studies on the lower jaw indicate that it was most likely not suitable for tearing animal food. The width and strong lower jaw is similar to that of Gastornis and Aepyornis, two herbivorous large birds. Likewise, the ungues of Brontornis do not show stronger bends compared to Phorusrhacids and thus do not allow raptor-like claws for tearing meat, which suggests a more plant-based diet.Buffetaut, E. THE BRONTORNITHIDAE: NEW DATA ABOUT AN OLD PALAEORNITHOLOGICAL RIDDLE. Considering its enormous body size, it is assumed that Brontornis inhabited more open landscapes, as they have also been proven for the Santa Cruz formation.Tambussi, C. P., & Degrange, F. (2012). South American and Antarctic continental Cenozoic birds: Paleobiogeographic affinities and disparities. Springer Science & Business Media. The short and wide Tarsometatarsus compared to the Tibiotarsus suggests a slow locomotion adapted to the enormous body mass.
|
|
