# Monotrematum

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***Monotrematum sudamericanum*** is an extinct [monotreme](/source/Monotreme) [species](/source/Species) from the Paleocene ([Peligran](/source/Peligran)) [Salamanca Formation](/source/Salamanca_Formation) in [Patagonia](/source/Patagonia), Argentina.[1] It is one of only two monotremes found outside [Oceania](/source/Oceania).

## Taxonomy

A species described in 1992 and assigned to a new genus ***Monotrematum*** as the type. It is currently the only known species of the genus. The authors compared their fossil material to the genus *[Obdurodon](/source/Obdurodon)*, [ornithorhynchid](/source/Ornithorhynchid) species first discovered at Australian fossil sites in 1975. It is considered to possibly be a [stem](/source/Stem_group)-ornithorhynchid, although this is uncertain given that several divergence estimates have found the family to be significantly younger.[2][3]

## Description

*Monotrematum sudamericanum* is known only from two lower and one upper [platypus](/source/Platypus)-like teeth. It is the only known non-[Australasian](/source/Australasia) [ornithorhynchid](/source/Ornithorhynchid). The main difference, apart from continent and age, is its size: the teeth of *Monotrematum* are around twice as large as those of other similar species in the related genus *[Obdurodon](/source/Obdurodon)*. The teeth of *M. sudamericanum* presently reside in the collections of [Museo de La Plata](/source/Museo_de_La_Plata) and [Museo Paleontológico Egidio Feruglio](/source/Museo_Paleontol%C3%B3gico_Egidio_Feruglio), both in Argentina.[4][5]

According to Pascual, "The preserved enamel in the central region shows that the crown pattern is almost identical to that of *Obdurodon*: it is composed of two V-shaped lobes, the anterior of which is wider, separated from the posterior one by a valley that connects the lingual and buccal sides of the crown separating the anterior and posterior lobes."

## References

1. [*Monotrematum*](https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=166671) at [Fossilworks](/source/Fossilworks).org

1. Flannery, T. F.; Rich, T. H.; Vickers-Rich, P.; Ziegler, T.; Veatch, E. G.; Helgen, K. M. (2022). "A review of monotreme (Monotremata) evolution". *Alcheringa: An Australasian Journal of Palaeontology*. **46** (1): 3–20. [Bibcode:2022Alch...46....3F](https://ui.adsabs.harvard.edu/abs/2022Alch...46....3F). [doi:10.1080/03115518.2022.2025900](https://doi.org/10.1080/03115518.2022.2025900). [S2CID 247542433](https://api.semanticscholar.org/CorpusID:247542433)

1. Flannery, Timothy F.; McCurry, Matthew R.; Rich, Thomas H.; Vickers-Rich, Patricia; Smith, Elizabeth T.; Helgen, Kristofer M. (2024-05-26). "A diverse assemblage of monotremes (Monotremata) from the Cenomanian Lightning Ridge fauna of New South Wales, Australia". *Alcheringa: An Australasian Journal of Palaeontology*. **48** (2): 319–337. [Bibcode:2024Alch...48..319F](https://ui.adsabs.harvard.edu/abs/2024Alch...48..319F). [doi:10.1080/03115518.2024.2348753](https://doi.org/10.1080/03115518.2024.2348753). [ISSN 0311-5518](https://www.worldcat.org/issn/0311-5518)

1. Pascual, R.; Archer, M.; Jaureguizar, E.O.; Prado, J.L.; Godthelp, H.; Hand, S.J. (1992). "First discovery of monotremes in South America". *Nature*. **356** (6371): 704–706. [Bibcode:1992Natur.356..704P](https://ui.adsabs.harvard.edu/abs/1992Natur.356..704P). [doi:10.1038/356704a0](https://doi.org/10.1038/356704a0)

1. Pascual, R.; Goin, F.J.; Balarino, L.; Sauthier, D.E.U. (2002). ["New data on the Paleocene monotreme *Monotrematum sudamericanum*, and the convergent evolution of triangulate molars"](https://www.app.pan.pl/archive/published/app47/app47-487.pdf). *Acta Palaeontologica Polonica*. **47** (3): 487–492. Retrieved 2020-01-21.

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Adapted from the Wikipedia article [Monotrematum](https://en.wikipedia.org/wiki/Monotrematum) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Monotrematum?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.