Equus neogeus

{{Short description|Extinct species of equine native to South America}}

{{speciesbox

| fossil_range = Pleistocene (Ensenadan-Lujanian) {{fossil range|1|0.012}}

| image = Amerhippus.jpg

| image_alt = Skull of "Equus neogeus"

| image_caption = Skull

| taxon = Equus neogeus

| authority = Lund, 1840

| extinct = yes

| synonyms = *{{extinct}}Equus (Amerhippus) andium

{{extinct}}Equus (Amerhippus) insulatus
{{extinct}}Equus (Amerhippus) lasallei
{{extinct}}Equus (Amerhippus) santaeelenae

| synonyms_ref =

}}

Equus neogeus is an extinct species of equine native to South America during the Pleistocene. It was formerly thought to be several distinct species within the subgenus Amerhippus, but was later shown to be a single morphologically variable species. It is thought to be closely related to true horses.

Taxonomy

While they have formerly been referred to as belonging to 5 separate species, this has been revised down into three,Prado, J. L., and Alberdi, M. T. (2017). Fossil Horses of South America. Springer International Publishing, 150 and more recently a single, morphologically variable species Equus neogeus.{{Cite journal|last1=Machado|first1=Helena|last2=Grillo|first2=Orlando|last3=Scott|first3=Eric|last4=Avilla|first4=Leonardo|date=September 2018|title=Following the Footsteps of the South American Equus: Are Autopodia Taxonomically Informative?|url=http://link.springer.com/10.1007/s10914-017-9389-6|journal=Journal of Mammalian Evolution|language=en|volume=25|issue=3|pages=397–405|doi=10.1007/s10914-017-9389-6|s2cid=22113020|issn=1064-7554|url-access=subscription}}{{Cite journal|last1=Machado|first1=Helena|last2=Avilla|first2=Leonardo|date=2019-07-03|title=The Diversity of South American Equus: Did Size Really Matter?|journal=Frontiers in Ecology and Evolution|volume=7|pages=235|doi=10.3389/fevo.2019.00235|issn=2296-701X|doi-access=free}} Some authors continue to recognise three species, restricting Equus neogeus to large-sized individuals spanning from the Pampas to Northeast Brazil, while separating the smaller Equus andium for populations in the northern-central Andes, and Equus insulatus for medium-sized animals spanning from Bolivia to Venezuela. These authors suggest that E. insulatus was the ancestor of the other species.{{Cite journal |last1=Prado |first1=José |last2=Alberdi |first2=María |date=2023 |title=DIVERSIDAD DE LOS ÉQUIDOS FÓSILES DE AMÉRICA DEL SUR Autores/as |url=https://www.peapaleontologica.org.ar/index.php/peapa/article/view/415 |journal=Publicación Electrónica de la Asociación Paleontológica Argentina |volume=23 |issue=1 |pages=241–254 |doi=10.5710/PEAPA.06.06.2022.415|doi-access=free }} Historically, South American Equus species were placed in the subgenus Amerhippus, but this has subsequently been questioned. A 2008 study of mitochondrial DNA fragments of a specimen of E. neogeus found it to be nested within mitochondrial lineages of E. caballus,{{Cite journal|last1=Orlando|first1=Ludovic|last2=Male|first2=Dean|last3=Alberdi|first3=Maria Teresa|last4=Prado|first4=Jose Luis|last5=Prieto|first5=Alfredo|last6=Cooper|first6=Alan|last7=Hänni|first7=Catherine|date=May 2008|title=Ancient DNA Clarifies the Evolutionary History of American Late Pleistocene Equids|url=http://link.springer.com/10.1007/s00239-008-9100-x|journal=Journal of Molecular Evolution|language=en|volume=66|issue=5|pages=533–538|doi=10.1007/s00239-008-9100-x|pmid=18398561|bibcode=2008JMolE..66..533O|s2cid=19069554|issn=0022-2844|url-access=subscription}} however, later studies suggested that this result required more specimens to be analysed for confirmation.{{Cite journal |last1=Barrón-Ortiz |first1=Christina I. |last2=Rodrigues |first2=Antonia T. |last3=Theodor |first3=Jessica M. |last4=Kooyman |first4=Brian P. |last5=Yang |first5=Dongya Y. |last6=Speller |first6=Camilla F. |date=2017-08-17 |editor-last=Orlando |editor-first=Ludovic |title=Cheek tooth morphology and ancient mitochondrial DNA of late Pleistocene horses from the western interior of North America: Implications for the taxonomy of North American Late Pleistocene Equus |journal=PLOS ONE |language=en |volume=12 |issue=8 |pages=e0183045 |doi=10.1371/journal.pone.0183045 |issn=1932-6203 |pmc=5560644 |pmid=28817644|bibcode=2017PLoSO..1283045B |doi-access=free }} A close relationship to caballine horses was also supported by a 2019 morphological analysis study.{{Cite journal|last1=Barrón-Ortiz|first1=Christina I.|last2=Avilla|first2=Leonardo S.|last3=Jass|first3=Christopher N.|last4=Bravo-Cuevas|first4=Víctor M.|last5=Machado|first5=Helena|last6=Mothé|first6=Dimila|date=2019-09-12|title=What Is Equus? Reconciling Taxonomy and Phylogenetic Analyses|journal=Frontiers in Ecology and Evolution|volume=7|pages=343|doi=10.3389/fevo.2019.00343|issn=2296-701X|doi-access=free}}

Description

File:Amerhippus A6 digital.jpg|left]]

Equus neogeus measured roughly {{convert|1.5|m|ft|abbr=on}} tall and weighed approximately {{convert|400|kg|lb|abbr=on}}.

Distribution

They were one of two groups of equines in South America, alongside Hippidion.{{Cite book|last1=PRADO|first1=JOSE LUIS|url=http://worldcat.org/oclc/1048948248|title=FOSSIL HORSES OF SOUTH AMERICA : phylogeny, systemics and ecology.|last2=ALBERDI|first2=MARIA TERESA|publisher=SPRINGER INTERNATIONAL PU|year=2018|isbn=978-3-319-85769-5|doi=10.1007/978-3-319-55877-6|s2cid=164732480|oclc=1048948248}} Fossils have been recovered from the Tarija Formation of Bolivia, the Serranía del Perijá in Venezuela, the Chiu-Chiu Formation of Chile, the Sabana Formation of the Bogotá savanna in Colombia,{{citation |last=De Porta |first=Jaime |authorlink=Jaime de Porta |year=1960 |title=Los Equidos fósiles de la Sabana de Bogotá |url=http://revistas.uis.edu.co/index.php/revistaboletindegeologia/article/view/4013 |journal=Boletín de Geología, Universidad Industrial de Santander |volume=4 |pages=51–78 |accessdate=2017-03-30}} and from various locations in Ecuador.{{Cite journal | last1 = Prado | first1 = J. L. | last2 = Alberdi | first2 = M. A. T. | last3 = De Reyes | first3 = M. N. L. | last4 = Poiré | first4 = D. G. | last5 = Canalicchio | first5 = J. M. | title = New material of Equus (Amerhippus) neogeus (Mammalia, Perissodactyla) from the late Pleistocene of Olavarría (Argentina) | doi = 10.1127/0077-7749/2013/0340 | journal = Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen | volume = 269 | issue = 2 | pages = 125 | year = 2013 | bibcode = 2013NJGPA.269..125P | hdl = 10261/115119 | hdl-access = free }} Equus first appeared in South America during the late Early Pleistocene-earliest Middle Pleistocene, around 1 million to 800,000 years ago, based on remains found near Tarija, Bolivia.{{Cite journal |last1=Cirilli |first1=Omar |last2=Machado |first2=Helena |last3=Arroyo-Cabrales |first3=Joaquin |last4=Barrón-Ortiz |first4=Christina I. |last5=Davis |first5=Edward |last6=Jass |first6=Christopher N. |last7=Jukar |first7=Advait M. |last8=Landry |first8=Zoe |last9=Marín-Leyva |first9=Alejandro H. |last10=Pandolfi |first10=Luca |last11=Pushkina |first11=Diana |last12=Rook |first12=Lorenzo |last13=Saarinen |first13=Juha |last14=Scott |first14=Eric |last15=Semprebon |first15=Gina |date=September 2022 |title=Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene |journal=Biology |language=en |volume=11 |issue=9 |pages=1258 |doi=10.3390/biology11091258 |issn=2079-7737 |pmc=9495906 |pmid=36138737 |doi-access=free}}

Paleobiology

A 2019 study suggested that Equus neogeus specimens from Uruguay were primarily grazers that fed on both C₄ and C₃ grasses in prairies and open woodlands.{{Cite journal |last1=Morosi |first1=Elizabeth |last2=Ubilla |first2=Martin |date=December 2019 |title=Feeding and environmental studies on late Pleistocene horses in mid-latitudes of South America (northern Uruguay) |url=https://linkinghub.elsevier.com/retrieve/pii/S0277379119305384 |journal=Quaternary Science Reviews |language=en |volume=225 |pages=106025 |doi=10.1016/j.quascirev.2019.106025|bibcode=2019QSRv..22506025M |s2cid=210240458 |url-access=subscription }}

Extinction

Equus neogeus became extinct at the end of the Late Pleistocene as part of the end-Pleistocene extinctions, along with the vast majority of other large mammals in South America.{{cite journal |author1=Anthony D. Barnosky |author2=Paul L. Koch |author3=Robert S. Feranec |author4=Scott L. Wing |author5=Alan B. Shabel |year=2004 |title=Assessing the Causes of Late Pleistocene Extinctions on the Continents |journal=Science |volume=306 |issue=5693 |pages=70–75 |bibcode=2004Sci...306...70B |citeseerx=10.1.1.574.332 |doi=10.1126/science.1101476 |pmid=15459379 |s2cid=36156087}} The youngest remains date to approximately 11,700 years Before Present (BP), in Río Quequén Salado, in the southwest of Buenos Aires province, Argentina. The extinctions followed human arrival to the Americas, and several sites show evidence of human interaction with Equus neogeus, which may have been a factor in its extinction. At the Paso Otero 5 site in the Pampas of northeast Argentina, Fishtail points are associated with burned bones of Equus neogeus and other extinct megafauna. The bones appear to have been deliberately burned as a source of fuel. Due to the poor preservation of the bones there is no clear evidence of human modification.G. Martínez, M. A. Gutiérrez, [https://www.researchgate.net/publication/255171250_Paso_Otero_5_a_summary_of_the_interdisciplinary_lines_of_evidence_for_reconstructing_early_human_occupation_and_paleoenvironment_in_the_Pampean_region_Argentina Paso Otero 5: A summary of the interdisciplinary lines of evidence for reconstructing early human occupation and paleoenvironment in the Pampean region, Argentina], in Peuplements et Préhistoire de l’Amérique, D. Vialou, Ed. (Muséum National d’ Histoire Naturelle. Departement de Prehistoire, U.M.R, Paris, 2011), pp. 271–284. At the Taguatagua 3 in central Chile, dating to around 12,440–12,550 years BP, a first phalanx of Equus was found near a hearth, alongside the remains of other megafuna, including the much more abundant remains of gomphotheres (elephant relatives).{{Cite journal |last1=Labarca |first1=Rafael |last2=Frugone-Álvarez |first2=Matías |last3=Vilches |first3=Liz |last4=Blanco |first4=José Francisco |last5=Peñaloza |first5=Ángela |last6=Godoy-Aguirre |first6=Carolina |last7=Lizama-Catalán |first7=Álvaro |last8=Oyarzo |first8=Cristóbal |last9=Tornero |first9=Carlos |last10=González-Guarda |first10=Erwin |last11=Delgado |first11=Ayelen |last12=Sepúlveda |first12=Marcela |last13=Soto-Huenchuman |first13=Paula |date=2024-05-22 |editor-last=Garvey |editor-first=Raven |title=Taguatagua 3: A new late Pleistocene settlement in a highly suitable lacustrine habitat in central Chile (34°S) |journal=PLOS ONE |language=en |volume=19 |issue=5 |pages=e0302465 |doi=10.1371/journal.pone.0302465 |doi-access=free |issn=1932-6203 |pmc=11111044 |pmid=38776357|bibcode=2024PLoSO..1902465L }} At the Arroyo Seco 2 site in the Argentinian Pampas, which has multiple episodes of human activity dating to between 14,782 and 11,142 cal yr BP remains of Equus neogeus (alongside those of other megafauna) are associated with human artifacts and exhibit fracture marks indicative of butchery.{{Cite journal |last1=Bampi |first1=Hugo |last2=Barberi |first2=Maira |last3=Lima-Ribeiro |first3=Matheus S. |date=December 2022 |title=Megafauna kill sites in South America: A critical review |url=https://linkinghub.elsevier.com/retrieve/pii/S0277379122004826 |journal=Quaternary Science Reviews |language=en |volume=298 |pages=107851 |bibcode=2022QSRv..29807851B |doi=10.1016/j.quascirev.2022.107851 |s2cid=253876769|url-access=subscription }}{{Cite journal |last1=Politis |first1=Gustavo G. |last2=Gutiérrez |first2=María A. |last3=Rafuse |first3=Daniel J. |last4=Blasi |first4=Adriana |date=2016-09-28 |editor-last=Petraglia |editor-first=Michael D. |title=The Arrival of Homo sapiens into the Southern Cone at 14,000 Years Ago |journal=PLOS ONE |language=en |volume=11 |issue=9 |pages=e0162870 |doi=10.1371/journal.pone.0162870 |doi-access=free |issn=1932-6203 |pmc=5040268 |pmid=27683248|bibcode=2016PLoSO..1162870P }}