# Prorastomus > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Prorastomus > Markdown URL: https://mediated.wiki/source/Prorastomus.md > Source: https://en.wikipedia.org/wiki/Prorastomus > Source revision: 1348584521 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Extinct genus of mammals}} {{Speciesbox |fossil_range = {{Fossil range|Middle Eocene}} |image = Prorastomus BW.jpg |parent_authority = [Owen](/source/Richard_Owen), 1855 |taxon = Prorastomus sirenoides |authority = [Owen](/source/Richard_Owen), 1855 }} '''''Prorastomus sirenoides''''' is an extinct species of primitive [sirenia](/source/sirenia)n that lived during the [Eocene](/source/Eocene) Epoch 40 million years ago in [Jamaica](/source/Jamaica). ==Taxonomy== The generic name ''Prorastomus'', a combination of [Greek](/source/Greek_language) {{lang|grc|πρῷρα}} (''prōra''), prow, and {{lang|grc|στόμα}} (''stoma''), mouth, refers to the lower jaw of the animal "resembling the prow of a [wherry](/source/wherry)". The [genus](/source/genus) name ''Prorastomus'' comes from [Greek](/source/Ancient_Greek) ''prora'' meaning "prow" and [Latin](/source/Latin) ''stomus'' meaning "mouth." In 1892, [naturalist](/source/naturalist) [Richard Lydekker](/source/Richard_Lydekker) respelled it as ''Prorastoma'' with a [feminine ending](/source/grammatical_gender), however this was unjustified as ''stomus'', masculine in Latin, has priority. ''Prorastomus'' is one of two [genera](/source/genera) of the family [Prorastomidae](/source/Prorastomidae), the other ''[Pezosiren](/source/Pezosiren)''. These two species are the oldest [sirenia](/source/sirenia)ns, dating to the [Eocene](/source/Eocene). The first specimen was [described](/source/species_description) by [paleontologist](/source/paleontologist) [Sir Richard Owen](/source/Sir_Richard_Owen) in 1855, and, being found in Jamaica in the [Yellow Limestone Group](/source/Yellow_Limestone_Group), pointed to the origin of Sirenia as being in the New World rather than the Old World as was previously thought. However, the modern understanding of [Afrotheria](/source/Afrotheria) as a clade that originally diversified in Africa overturns this idea. The [holotype specimen](/source/holotype_specimen), BMNH 44897, comprises a skull, jaw, and [atlas](/source/atlas_(anatomy)) of the [neck vertebra](/source/neck_vertebra)e. When Owen first acquired the skull, it was broken in two between the eyes and the [braincase](/source/braincase). Another specimen was found in 1989 in the same formation, USNM 437769, comprising the [frontal bone](/source/frontal_bone), a tusk, vertebrae fragments, and [rib](/source/rib)s. ==Description== [[File:Prorastomus vertebra FLMNH.jpg|thumb|Fossil vertebra, [Florida Museum of Natural History](/source/Florida_Museum_of_Natural_History)]] While modern sirenians are fully aquatic, the {{convert|1.5|m|ft|sigfig=1|adj=on}} ''Prorastomus'' was predominantly terrestrial, judging from the structure of its skull. Judging from its crown-shaped [molars](/source/molar_(tooth)) and the shape of its snout, it fed on soft plants.{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals|publisher= Marshall Editions|location=London|page= 229|isbn= 1-84028-152-9}} The snout is long, narrow, and, at the tip, bulbous. The [nasal bone](/source/nasal_bone)s are larger than other sirenians. The [nasal ridge](/source/nasal_ridge) is well developed, indicating it had a good sense of smell. The [frontal bone](/source/frontal_bone)s are smaller than usual for sirenians, though, as in other sirenians, it had a pronounced [brow ridge](/source/brow_ridge).{{cite journal|first1=R. J. G.|last1=Savage|first2=D. P.|last2=Domning|first3=J. G. M.|last3=Thewissen|year=1994|title=Fossil Sirenia of the West Atlantic and Caribbean Region. V. the Most Primitive Known Sirenian, Prorastomus sirenoides Owen, 1855|journal=Journal of Vertebrate Paleontology|volume=14|issue=3|pages=427–449|doi=10.1080/02724634.1994.10011569|bibcode=1994JVPal..14..427S }} Since ''Pezosiren'' has a [sagittal crest](/source/sagittal_crest), it is possible the ''Prorastomus'' specimen had one too before being eroded away.{{cite journal|first=D. P.|last=Domning|year=2001|title=The earliest known fully quadrupedal sirenian|journal=Nature|volume=413|issue=6856 |pages=625–627|doi=10.1038/35098072|pmid=11675784|bibcode=2001Natur.413..625D |s2cid=22005691 |url=https://www.researchgate.net/publication/11676587}} == See also == {{Portal|Paleontology}} *[Evolution of sirenians](/source/Evolution_of_sirenians) *''[Pezosiren](/source/Pezosiren)'' ==References== {{Reflist}} *Barry Cox, Colin Harrison, R. J. G. Savage, and Brian Gardiner. (1999): The Simon & Schuster Encyclopedia of Dinosaurs and Prehistoric Creatures: A Visual Who's Who of Prehistoric Life. [Simon & Schuster](/source/Simon_%26_Schuster). *David Norman. (2001): The Big Book Of Dinosaurs. Pg. 348, Welcome Books. *Richard Owen. (1855): On the fossil skull of a mammal (''Prorastomus sirenoïdes'', Owen) from the island of Jamaica. The Quarterly journal of the Geological Society of London, 11, pp. 541–543. {{Sirenian genera}} {{Taxonbar|from=Q27057242}} Category:Eocene mammals of North America Category:Eocene sirenians Category:Transitional fossils Category:Monotypic prehistoric placental genera Category:Taxa named by Richard Owen Category:Fossil taxa described in 1855 Category:Paleogene Jamaica Category:Fossils of Jamaica {{Paleo-sirenian-stub}} --- Adapted from the Wikipedia article [Prorastomus](https://en.wikipedia.org/wiki/Prorastomus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Prorastomus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.