View source for Trichechus hesperamazonicus

{{Short description|Extinct species of manatee}}
{{Speciesbox
| fossil_range = {{Fossil range|Late Pleistocene}}
| image = Tichechus hesperamazonicus.jpeg
| extinct = yes
| genus = Trichechus
| species = hesperamazonicus
| authority = Perini, Nascimento & Cozzuol 2020
}}
'''''Trichechus hesperamazonicus''''', the '''western Amazonian manatee''', is an extinct species of [[manatee]] that lived about 40 thousand years ago in the [[Madeira River]], in the Brazilian state of [[Rondonia]].<ref name=":0">{{Cite journal|last1=Perini|first1=Fernando A.|last2=Nascimento|first2=Ednair Rodrigues|last3=Cozzuol|first3=Mario Alberto|date=2019-09-03|title=A new species of Trichechus Linnaeus, 1758 (Sirenia, Trichechidae), from the upper Pleistocene of southwestern Amazonia, and the evolution of Amazonian manatees|url=https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1697882|journal=Journal of Vertebrate Paleontology|language=en|volume=39|issue=5|pages=e1697882|doi=10.1080/02724634.2019.1697882|bibcode=2019JVPal..39E7882P |s2cid=212816367|issn=0272-4634}}</ref><ref name=":1">{{Cite web|title=Trichechus hesperamazonicus|url=https://paleobiodb.org/classic/basicTaxonInfo?taxon_no=404398|website=The Paleobiology Database}}</ref> It is known from this single locality, with possible occurrences in the Brazilian state of [[Acre (state)|Acre]].<ref name=":0" />
== Description ==
''Trichechus hesperamazonicus'' is known by two fragmentary mandibles and part of the palate. Compared with other manatees, it has a wide space between the posterior lower tooth row and ascending ramus of [[dentary]], where the [[buccinator]] muscle is located, and a wide ascending ramus of the [[mandible]], which covers the posterior end of the tooth row.<ref name=":0" /><ref name=":2">{{Cite journal|last=Zorzetto|first=Ricardo|title=O antigo peixe-boi de Rondônia|url=https://revistapesquisa.fapesp.br/2020/03/05/o-antigo-peixe-boi-de-rondonia/|journal=Pesquisa FAPESP|volume=289|pages=60–61}}</ref> It also shares some characteristics with living species, as relatively few large teeth and few mental foramina as ''[[Trichechus manatus|T. manatus]]'' and ''[[Trichechus senegalensis|T. senegalensis]]'' (in contrast with the many smaller teeth and many mental foramina of ''[[Trichechus inunguis|T. inunguis]]'') and a straight and shallow mandibular symphysis as ''[[Trichechus inunguis|T. inunguis]]'' and ''[[Trichechus senegalensis|T. senegalensis]]'' (in contrast with the downturned snout and deep mandibular symphysis of ''[[Trichechus manatus|T. manatus]]'').<ref name=":0" /> The affinities of this species are still not fully resolved, being recovered in a polytomy with ''[[Trichechus inunguis|T. inunguis]]'' and a clade formed by ''[[Trichechus manatus|T. manatus]]'' and ''[[Trichechus senegalensis|T. senegalensis]]'':<ref name=":0" />
{{clade|{{clade
|1={{clade
|newick1=(†''[[Potamosiren magdalenensis]]'',(†''[[Ribodon limbatus]]'',(†'''''Trichechus hesperamazonicus''''',''[[Trichechus inunguis]]'',(''[[Trichechus senegalensis]]'',''[[Trichechus manatus]]''))))
|1=Leaf B
}}
}}}}
== Distribution ==
The [[Latin]] name ''hesperamazonicus'' refers to the western localization of the species, ''hesperos'' (west) and ''amazonicus'' (from the Amazon region). The fossil was found near the village of [[Araras]], in [[Nova Mamoré]], state of [[Rondonia]], [[Brazil]]. Since the [[Rio Madeira Formation]]. The site also yielded [[pampatheres]], a fossil species of [[tapir]]<ref name=":1" /><ref>{{Cite journal|last1=Góis|first1=Flávio|last2=Scillato-Yané|first2=Gustavo Juan|last3=Carlini|first3=Alfredo Armando|last4=Ubilla|first4=Martín|date=2012-08-31|title=Una nueva especie de Holmesina Simpson (Xenarthra, Cingulata, Pampatheriidae) del Pleistoceno de Rondônia, sudoeste de la Amazonia, Brasil|journal=Revista Brasileira de Paleontologia|url=http://www.sbpbrasil.org/revista/edicoes/15_2/RBP_09_Gois_et_al_Final.pdf|volume=15|issue=2|pages=211–227|doi=10.4072/rbp.2012.2.09|doi-access=free}}</ref><ref>{{Cite journal|last1=Holanda|first1=Elizete C.|last2=Ferigolo|first2=Jorge|last3=Ribeiro|first3=Ana Maria|date=2011-02-16|title=New Tapirus species (Mammalia: Perissodactyla: Tapiridae) from the upper Pleistocene of Amazonia, Brazil|journal=Journal of Mammalogy|language=en|volume=92|issue=1|pages=111–120|doi=10.1644/10-MAMM-A-144.1|issn=0022-2372|doi-access=free}}</ref> and the [[Podocnemididae|podocnemidid river turtle]] [[Peltocephalus maturin]]<ref>{{Cite journal|last1=Ferreira |first1=G. S. |last2=Nasciemento |first2=E. R. |last3=Cadena |first3=E. A. |last4=Cozzuol |first4=M. A. |last5=Farina |first5=B. M. |last6=Pacheco |first6=M. L. A. F. |last7=Rizzutto |first7=M. A. |last8=Langer |first8=M. C. |year=2024 |title=The latest freshwater giants: a new Peltocephalus (Pleurodira: Podocnemididae) turtle from the Late Pleistocene of the Brazilian Amazon |journal=Biology Letters |volume=20 |issue=3 |at=20240010 |doi=10.1098/rsbl.2024.0010 |pmid=38471564 |pmc=10932709 }}</ref>.<sup>14</sup>C dates from associated wood samples give an age of 44,710 ± 880 years before present.<ref name=":0" /> At that time, the [[Madeira River]] had slow currents and many marginal lakes. At the end of the [[Pleistocene]], changes on the river regime originated several [[rapids]], creating an environment unsuitable to manatees, that are currently absent from the region.<ref name=":0" /><ref name=":2" />
== References ==
{{Reflist}}
{{Taxonbar|from=Q96057722}}
[[Category:Manatees]]
[[Category:Fossil taxa described in 2020]]
[[Category:Prehistoric mammals]]