Biology:Rhadinorhinina
Rhadinorhines (subtribe Rhadinorhinina) were a group, or clade, of derived (advanced) brontotheres. Rhadinorhines were small to intermediate-sized brontotheres, known only from the Middle Eocene (Uintan) of western North America.
Description
Rhadinorhines are known only from cranial fossils (skulls, jaws, and teeth).[1][2] They were small to intermediate-sized brontotheres[1] that share a single securely identified apomorphy (shared evolved trait): that the premaxillomaxillary rostrum (the snout of the animal, below the nasal incision) does not deepen ventrally (towards the underside).[1] This trait is also seen in the more distantly related Dolichorhinus hyognathus, though is in that case treated as a case of convergent evolution.[1]
Classification
History, systematics, and phylogenetics
Fossendorhinus diploconus was the first rhadinorhine to be described, by Henry Fairfield Osborn in 1895, under the name "Telmatotherium diploconum".[3] In 1929, Osborn named the brontothere subfamily "Rhadinorhininae" to encompass only the genus Rhadinorhinus, which per Osborn's taxonomy included the two species R. abbotti and R. diploconus (formerly T. diploconum).[3] Osborn placed the genus Metarhinus in a separate subfamily, "Dolichorhininae", alongside the genera Dolichorhinus, Mesatirhinus, and Sphenocoelus.[3]
Rhadinorhinus is today considered a junior synonym of Metarhinus.[1] In a major 2008 brontothere monograph, Matthew C. Mihlbachler transferred "R". diploconus to the distinct genus Fossendorhinus.[1] In a phylogenetic analysis performed for the monograph, Mihlbachler recovered a small clade containing Metarhinus and Fossendorhinus. Mihlbachler referred to this clade as Rhadinorhinina, having reranked "Rhadinorhininae" to the status of a subtribe to fit with his larger-scale systematic revision of the brontotheres.[1] Rhadinorhinina was not recovered as a clade in a 2016 analysis by Mihlbachler and Thomas A. Deméré,[2] but recovered again in a 2021 analysis by Mihlbachler and Donald Prothero.[4] The cladograms below show brontothere classification per the primary strict reduced consensus tree from Mihlbachler's 2008 analysis,[1] and the reduced strict consensus tree from the 2021 analysis by Mihlbachler and Prothero:[4]
Topology A: Mihlbachler (2008)[1]
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Topology B: Mihlbachler & Prothero (2021)[4]
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Etymology
The name Rhadinorhinina is derived from the now invalid genus Rhadinorhinus[3] (=Metarhinus).[1] Rhadinorhinus means "slender nose", from the Greek ῥαδινός (rhadinós, "slender") and ῥινος (rhinos, "nose").[3] Members of the Rhadinorhinina are informally referred to as "rhadinorhines".[3]
Evolutionary history and paleobiogeography
The two known rhadinorhine genera, Fossendorhinus and Metarhinus, are known only from the Uintan land mammal age[5] of the western United States.[1] Metarhinus is known from Wyoming, Utah, and California,[1][2] from deposits of early to middle Uintan age (Ui1–Ui2).[5] Fossendorhinus is known from the middle Uintan (mid-to-late Ui2)[5] of Utah.[1]
Notes
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Mihlbachler, Matthew C. (2008). [1:STPABO2.0.CO;2.full "Species Taxonomy, Phylogeny, and Biogeography of the Brontotheriidae (Mammalia: Perissodactyla)"]. Bulletin of the American Museum of Natural History 2008 (311). doi:10.1206/0003-0090(2008)501[1:STPABO2.0.CO;2]. https://bioone.org/journals/bulletin-of-the-american-museum-of-natural-history/volume-2008/issue-311/0003-0090(2008)501%5b1%3aSTPABO%5d2.0.CO%3b2/Species-Taxonomy-Phylogeny-and-Biogeography-of-the-Brontotheriidae-Mammalia/10.1206/0003-0090(2008)501[1:STPABO]2.0.CO;2.full.
- ↑ 2.0 2.1 2.2 Mihlbachler, Matthew C.; Deméré, Thomas A. (2010). "Phylogenetic status of Metarhinus pater (Brontotheriidae: Perissodactyla) from Southern California and species variation in Metarhinus from the middle Eocene of North America" (in en). Journal of Vertebrate Paleontology 30 (4): 1229–1244. doi:10.1080/02724634.2010.483568. ISSN 0272-4634. http://www.tandfonline.com/doi/abs/10.1080/02724634.2010.483568.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Osborn, Henry F. (1929). The Titanotheres of Ancient Wyoming, Dakota, and Nebraska, Volume 1. Department of the Interior, U.S. Geological Survey. pp. 156, 248. https://archive.org/details/titanotheresofan01osbo/.
- ↑ 4.0 4.1 4.2 Mihlbachler, Matthew C.; Prothero, Donald R. (2021). "Eocene (Duchesnean and earliest Chadronian) brontotheres (Brontotheriidae), Protitanops curryi and cf. Parvicornus occidentalis, from West Texas and Mexico". Palaeontologia Electronica 24 (3): a35. doi:10.26879/944. https://palaeo-electronica.org/content/2021/3479-texas-brontotheriidae.
- ↑ 5.0 5.1 5.2 Hodnett, John-Paul M.; Welsh, Edward T.; Santucci, Vincent L.; Tweet, Justin S. (2022). "A Middle Eocene brontothere (Mammalia; Perissodactyla; Brontotheriidae) from Yellowstone National Park, Wyoming" (in en). FOSSIL RECORD 8. New Mexico Museum of Natural History and Science. pp. 211. https://books.google.com/books?id=YCKIEAAAQBAJ.
Template:Brontotheriidae Wikidata ☰ Q33230008 entry
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