Titanodectes

Titanodectes
Temporal range: Middle–Late Eocene (Sharamurunian–Ulangochuian[a]), 42.7–37.8 Ma
A–C: the type jaw of T. ingens (AMNH 26005)
D: part of the type jaw of T. minor (AMNH 26132)
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Placentalia
Order: Perissodactyla
Family: †Brontotheriidae
Subfamily: †Brontotheriinae
Tribe: †Brontotheriini
Subtribe: †Brontotheriina
Infratribe: †Embolotheriita
Genus: †Titanodectes
Granger & Gregory, 1943[1]
Type species
†Titanodectes ingens
Granger & Gregory, 1943[1]
Other species
  • †T. minor Granger & Gregory, 1943[1]

Titanodectes (lit. 'titanic biter'[b]) is an extinct genus of horned brontothere that lived in East Asia during the Middle to Late Eocene, in the Sharamurunian and Ulangochuian land mammal ages.[a] Two species of Titanodectes have been named, the type species T. ingens and the smaller T. minor, both known from Inner Mongolia in China.

Titanodectes was a very large brontothere, though its precise size is unknown since it is known only from lower jaws. The largest known Titanodectes jaw, assigned to T. ingens, measures 69 centimeters (27 in) long.

Research history

Titanodectes was described by Walter W. Granger and William King Gregory in 1943. The type species, T. ingens, was based on a large lower jaw, preserving the front teeth and some worn cheek teeth (AMNH 26005). Granger and Gregory also named a second species, T. minor, based on an incomplete lower jaw with only some of the teeth preserved (AMNH 26132).[1] Both of the type specimens were recorded by Granger and Gregory to be from the Shara Murun Formation of Inner Mongolia; precise locality data was provided only for the T. ingens jaw, which was found at Jhama Obo, East Mesa.[1] Bai et al. (2020) reassessed AMNH 26005 to actually be from the Ulan Gochu Formation, but maintained a Shara Murun provenance for AMNH 26132.[3] Granger and Gregory also referred some additional fossils to T. minor, including another incomplete jaw from the Shara Murun Formation (AMNH 21600), as well as two incomplete jaws from the slightly later Ulan Gochu Formation (AMNH 26021 and AMNH 26012).[1] Titanodectes was distinguished from Embolotherium mainly by dental features compared to juvenile lower jaws referred to Embolotherium.[1][7] Granger and Gregory considered Titanodectes to be intermediate between Rhinotitan and Embolotherium.[1] The two Titanodectes species were distinguished from each other by Granger and Gregory mainly by the larger size of T. ingens.[1][7]

In 2004, Matthew C. Mihlbachler, Spencer G. Lucas, Robert J. Emry, and Bolat Bayshashov referred to Titanodectes as a "somewhat dubious taxon".[8] In 2008, Mihlbachler designated both Titanodectes species as junior synonyms of Embolotherium grangeri, and treated all of the Titanodectes fossils as lower jaws of adult E. grangeri.[7] Mihlbachler pointed out errors in Granger and Gregory's interpretations of the dentition of the fossils, notably that they had erroneously believed that adult Embolotherium retained deciduous incisors.[7] Mihlbachler also referred one of the two Ulan Gochu lower jaws, AMNH 26012, to Parabrontops cf. gobiensis.[7][9]

In 2018, Bai et al. rejected the synonymization with Embolotherium and treated Titanodectes as a valid genus, noting that no reliable lower dentition of E. grangeri has been reported (making actual comparison impossible), and that Titanodectes and Embolotherium are known from different localities, and different horizons.[9]

Description

Titanodectes was a very large brontothere.[1] The lower jaw of T. ingens measured 69 centimeters (27 in) and that of T. minor measured 61.9 centimeters (24.4 in).[1]

Since Titanodectes is known only from lower jaws, little can be said about its overall appearance. The skull of Titanodectes, at least T. ingens, was probably similar to that of the closely related Embolotherium.[1] The eight lower front teeth of Titanodectes (three pairs of incisors, and one pair of canines) were arranged in a slightly curved row and forwardly directed scoop.[1] Both the incisors and molars were exceptionally large, while the canines were relatively small.[1]

Classification

Granger and Gregory classified Titanodectes in the brontothere subfamily Embolotheriinae.[1] In modern brontothere taxonomy, this subfamily corresponds to the infratribe Embolotheriita.[7]

Notes

  1. ^ a b Per their original descriptions, the fossils of both T. ingens and T. minor were found in the Shara Murun Formation, and additional fossils from T. minor were found in the Ulan Gochu Formation.[1] This would make both species Sharamurunian in age, with T. minor persisting into the Ulangochuian. Later assessments have varied slightly. Bai et al. (2020) placed Titanodectes later, in the Ulangochuian and Ergilian, and not in the Sharamurunian at all.[2] Bai et al. (2025) reassessed the T. ingens specimen AMNH 26005 to be from the Ulan Gochu Formation, not the Shara Murun Formation, placing T. ingens only in the Ulangochuian. The original provenances for the T. minor fossils were retained, placing that species in the Sharamurunian and Ulangochuian.[3]
  2. ^ From Greek Τιτάν (Tītā́n, Titan)[4] and δεκτες (dektes, "biter").[5][6]

References

  1. ^ a b c d e f g h i j k l m n o p Granger, Walter W.; Gregory, William K. (1943). "A revision of the Mongolian titanotheres". American Museum Novitates. 80: 349–389.
  2. ^ Bai, Bin; Meng, Jin; Janis, Christine M.; Zhang, Zhao‐Qun; Wang, Yuan‐Qing (2020). "Perissodactyl diversities and responses to climate changes as reflected by dental homogeneity during the Cenozoic in Asia". Ecology and Evolution. 10 (13): 6333–6355. doi:10.1002/ece3.6363. ISSN 2045-7758. PMC 7381588. PMID 32724516.
  3. ^ a b Bai, Bin; Li, Qian; Zhou, Xin-Ying; Wang, Xiao-Yang; Xu, Ran-Cheng; Zhang, Xin-Yue; Quan, Shuo-Shuo; Meng, Jin; Wang, Yuan-Qing (2025). "Litho- and Biostratigraphy of the East Mesa in Shara Murun Region of the Erlian Basin, Inner Mongolia, China, and the subdivision of the Ulangochuian Asian Land Mammal Age". American Museum Novitates. 2025 (4034). doi:10.1206/4034.1. ISSN 0003-0082.
  4. ^ Osborn, Henry F. (1929). The Titanotheres of Ancient Wyoming, Dakota, and Nebraska, Volume 1. Department of the Interior, U.S. Geological Survey. p. 205.
  5. ^ Modesto, Sean P.; Damiani, Ross; Neveling, Johann; Yates, Adam M. (2004). "Saurodektes gen. nov., a new generic name for the owenettid parareptile Saurodectes Modesto et al., 2003". Journal of Vertebrate Paleontology. 24 (4): 970–970. doi:10.1671/0272-4634(2004)024[0970:SGNANG]2.0.CO;2. ISSN 0272-4634.
  6. ^ Modesto, Sean; Rubidge, Bruce; Visser, Ian; Welman, Johann (2003). "A new basal dicynodont from the Upper Permian of South Africa". Palaeontology. 46 (1): 211–223. doi:10.1111/1475-4983.00295. ISSN 0031-0239.
  7. ^ a b c d e f Mihlbachler, Matthew C. (2008). "Species Taxonomy, Phylogeny, and Biogeography of the Brontotheriidae (Mammalia: Perissodactyla)". Bulletin of the American Museum of Natural History. 2008 (311): 1–475. doi:10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2. ISSN 0003-0090.
  8. ^ Mihlbachler, Matthew C.; Lucas, Spencer G.; Emry, Robert J.; Bayshashov, Bolat (2004). "A New Brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a Phylogeny of Asian "Horned" Brontotheres". American Museum Novitates. 3439 (1). doi:10.1206/0003-0082(2004)439<0001:ANBBPM>2.0.CO;2. ISSN 0003-0082.
  9. ^ a b Bai, Bin; Wang, Yuan-Qing; Li, Qian; Wang, Hai-Bing; Mao, Fang-Yuan; Gong, Yan-Xin; Meng, Jin (2018). "Biostratigraphy and Diversity of Paleogene Perissodactyls from the Erlian Basin of Inner Mongolia, China". American Museum Novitates. 3914 (3914): 1–60. doi:10.1206/3914.1. ISSN 0003-0082.

Content Disclaimer

Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.

  1. The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
  2. There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
  3. It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
  4. Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
  5. Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.