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Teviornis

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Teviornis
Temporal range: Late Cretaceous, 70 Ma
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Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Family: †Presbyornithidae
Genus: †Teviornis
Kurochkin, Dyke & Karhu, 2002
Species:
†T. gobiensis
Binomial name
†Teviornis gobiensis
Kurochkin, Dyke & Karhu, 2002

Teviornis is an extinct genus of presbyornithid which lived during the Maastrichtian stage, around 70 million years ago. One species has been described, T. gobiensis. It is the oldest known neognath and its fossils are collected from the Nemegt Formation of Mongolia.[1]

Discovery and naming

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The fossils were collected at the Gurilyn tsav locality, northwest corner of Umnogobi Aimak, Mongolia. The holotype consists of a crushed partial right forelimb. These pieces include a nearly complete right carpometacarpus, two phalanges, the radiale and ulnare of the wrist, and a fragment of the distal right humerus. The catalog number of these fossils are given multiple times as PIN 4499–1, but they are listed as PIN 44991–1 on page 3, where the holotype is formally listed. This is probably a misprint.[2]

The genus name Teviornis is the Greek masculine word for bird combined with the name of Victor Tereschenko, the Paleontologist at the PIN who discovered the specimen. The species name T. gobiensis refers to the harsh Gobi Desert in which the fossil was found. The fossils are in the collection of the Paleontological Institute, Russian Academy of Sciences, Moscow.[2]

Classification

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In 2002, Teviornis was described by Kurochkin, Dyke & Karhu as a member of the Presbyornithidae. These were stilt-legged, Anseriform, waterfowl which are extinct, but which flourished during the Late Cretaceous and Paleogene. If Teviornis does belong to the Presbyornithidae then, together with Vegavis from Antarctica, there is evidence that relatives of today's waterfowl already were widespread and highly apomorphic by the end of the Mesozoic.[2]

Clarke and Norell reviewed the specimen in 2004. They concluded that some of the characters used by Kurochkin et al. to assign T. gobiensis to the Anseriformes, such as an unbowed metacarpal III, are plesiomorphies which are primitive for Avialae and also retained in some members of Ornithurae. They found that the remaining characters used by Kurochkin et al. also had wider distribution than was assumed, or had an incompletely studied distribution. Moreover, Clarke and Norell found no synapomorphies of Aves (sensu Gauthier), Neognathae, or Galloanseres, preserved in PIN 4499–1, so they concluded that Teviornis cannot be confidently assigned to the Presbyornithidae.[3]

In 2016, De Pietri and colleagues reassessed the type specimen of Teviornis and confirmed the taxon's identity as a presbyornithid on the basis of the trochlea carpalis extension (a bony articular process that drives wing extension and flexion), elongate sulcus tendineus, metacarpal synostosis, etc. Certain morphological traits of the type specimen including the facies articularis dimension and the craniocaudally elongated fossa are also found in the other presbyornithids such as Wilaru and Telmabates. Its non-curved carpometacarpus also confirms its identity as an anseriform outside the crown-group.[4] A 2019 study also supports the placement of presbyornithids as stem anseriforms.[5] In 2020, a possible Eocene presbyornithid specimen from Algeria notably showed similarity to Teviornis based on the carpal trochlea extension and the shape of the fossa, reaffirming the taxonomic identity of this taxon as a presbyornithid.[6]

References

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  1. ^ Marjanović, D. (2021). "The Making of Calibration Sausage Exemplified by Recalibrating the Transcriptomic Timetree of Jawed Vertebrates". Frontiers in Genetics. 12. 521693. doi:10.3389/fgene.2021.521693. PMC 8149952. PMID 34054911.
  2. ^ a b c Kurochkin, E. N.; Dyke, G. J.; Karhu, A. A. (2002). "A new presbyornithid bird (Aves, Anseriformes) from the late Cretaceous of southern Mongolia". American Museum Novitates (3386): 1–11. doi:10.1206/0003-0082(2002)386<0001:ANPBAA>2.0.CO;2. hdl:2246/2875. S2CID 59147935.
  3. ^ Clarke, Julia A., Norell, Mark A. (2004) "New Avialan Remains and a Review of the Late Cretaceous Nemegt Formation of Mongolia" "American Museum Novitates" Number 3447, 12pp. June 2, 2004
  4. ^ De Pietri, V.L.; Scofield, R.P.; Zelenkov, N.; Boles, W.E.; Worthy, T.H. (2016). "The unexpected survival of an ancient lineage of anseriform birds into the Neogene of Australia: the youngest record of Presbyornithidae". Royal Society Open Science. 3 (2): 150635. Bibcode:2016RSOS....350635D. doi:10.1098/rsos.150635. PMC 4785986. PMID 26998335.
  5. ^ Claudia P. Tambussi; Federico J. Degrange; Ricardo S. De Mendoza; Emilia Sferco; Sergrio Santillana (2019). "A stem anseriform from the early Palaeocene of Antarctica provides new key evidence in the early evolution of waterfowl". Zoological Journal of the Linnean Society. 186 (3): 673–700. doi:10.1093/zoolinnean/zly085.
  6. ^ Géraldine Garcia; Cécile Mourer-Chauviré; Mohammed Adaci; Mustapha Bensalah; Fateh Mebrouk; Xavier Valentin; M'hammed Mahboubi; Rodolphe Tabuce (2020). "First discovery of avian egg and bone remains (Presbyornithidae) from the Gour Lazib (Eocene, Algeria)" (PDF). Journal of African Earth Sciences. 162: Article 103666. Bibcode:2020JAfES.16203666G. doi:10.1016/j.jafrearsci.2019.103666. S2CID 210607715.
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