{"id":66322,"date":"2025-09-15T22:28:07","date_gmt":"2025-09-15T22:28:07","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/66322\/"},"modified":"2025-09-15T22:28:07","modified_gmt":"2025-09-15T22:28:07","slug":"new-species-of-extinct-octodontoid-rodent-discovered-from-amazonian-fossil","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/66322\/","title":{"rendered":"New Species of Extinct Octodontoid Rodent Discovered from Amazonian Fossil"},"content":{"rendered":"

Paleontologists have identified a new species of rodent in Acarechimys<\/a>, an extinct genus with a widespread South American distribution, from a partial jaw and teeth unearthed in Brazil.<\/strong><\/p>\n

\"Hypothetical<\/a><\/p>\n

Hypothetical reconstruction of Acarechimys hunikuini. Image credit: M\u00e1rcio Castro.<\/p>\n

Acarechimys hunikuini lived in what is now Brazilian Amazonia around 10 million years ago (Late Miocene epoch).<\/p>\n

The ancient species belongs to Octodontoidea<\/a>, a family of Neotropical hystricognathous rodents within the parvorder Caviomorpha<\/a>.<\/p>\n

\u201cHystricognathous rodents of the Neotropics, i.e., Caviomorpha, are a fascinating mammal group because of their astonishing taxonomic and ecological diversity, which reflects a complex evolutionary history,\u201d said Dr. Emmanuelle Fontoura, a paleontologist with the Universidade Federal de Santa Maria and CAPPA-Centro de Apoio \u00e0 Pesquisa Paleontol\u00f3gica da Quarta Col\u00f4nia, and colleagues.<\/p>\n

\u201cThese rodents appear suddenly in the South American fossil record at the end of the Eocene epoch, at least from what we know from the available record, especially that of Peruvian Amazonia.\u201d<\/p>\n

\u201cBy the Early Oligocene, they had already diversified, with the first representatives of the crown groups.\u201d<\/p>\n

\u201cPresent\u2010day caviomorphs comprise 266 species, structured into two major clades and four superfamilies: i) Erethicavioi grouping Cavioidea (e.g., guinea pig and related forms) and Erethizontoidea (New World porcupines), and ii) Octochinchilloi with Chinchilloidea (chinchilla and pacaranas) and Octodontoidea (e.g., spiny rats and related forms).\u201d<\/p>\n

\u201cThe superfamily Octodontoidea includes the extant families Abrocomidae, Echimyidae, Octodontidae and Ctenomyidae, plus extinct lineages.\u201d<\/p>\n

\u201cThis is the richest and most diverse clade among Caviomorpha, both taxonomically and phenotypically through time.\u201d<\/p>\n

The dental remains of Acarechimys hunikuini were collected during field trips in 2019 and 2022 at the PRE06 outcrop of the Solim\u00f5es Formation<\/a> near the city of Feij\u00f3 in the Brazilian state of Acre.<\/p>\n

\u201cThe Solim\u00f5es Formation has yielded a great diversity of vertebrate fossils since the mid\u201019th century,\u201d the paleontologists said.<\/p>\n

\u201cFossil\u2010bearing localities from this formation were recently dated, revealing maximum ages of deposition within the Tortonian, i.e., Upper Miocene.\u201d<\/p>\n

\u201cMammals are among the most diverse fossils found there, including bats, cetaceans, litopterns, marsupials, notoungulates, primates, rodents, sirenians, and xenarthrans.\u201d<\/p>\n

\u201cIn addition, fossil remains of birds, crocodilians, chelonians, fishes, amphibians, invertebrates, ichnofossils, and plants have also been documented.\u201d<\/p>\n

The discovery of Acarechimys hunikuini shows that several superfamilies of caviomorphous rodents co-existed in this region, in addition to many other animal groups, highlighting the existence of a rich fauna in the Brazilian Amazonia.<\/p>\n

\u201cAcarechimys possibly emerged during the Late Oligocene and diversified in the Patagonian region during the Early Miocene,\u201d the researchers said.<\/p>\n

\u201cDuring the Middle Miocene, it spread to extra\u2010Patagonian regions, towards the north of South America.\u201d<\/p>\n

\u201cDuring the Late Miocene, the lineage remained only in extra\u2010Patagonian regions.\u201d<\/p>\n

\u201cThis new record, which is the last appearance of the genus, supports the hypothesis of the late survival of rodent lineages in the tropics, a pattern that has been documented in octodontoids, hydrochoerines and neoepiblemids.\u201d<\/p>\n

\u201cThe rapid diversification and radiation of Acarechimys, as well as the scarcity of data, divergence of opinions between studies dedicated to this group, and the many isolated teeth reported for the Amazonian region, make the research of this genus challenging.\u201d<\/p>\n

\u201cFurther research is required to enhance our comprehension of the diversification and temporal variation of this broad lineage of Octodontoidea.\u201d<\/p>\n

The team\u2019s paper<\/a> was published in the Journal of Vertebrate Paleontology.<\/p>\n

_____<\/p>\n

Emmanuelle Fontoura et al. 2024. A new Late Miocene stem Octodontoid (Rodentia: Caviomorpha: Octochinchilloi) from the Solim\u00f5es Formation (Brazil): paleobiogeographic implications. Journal of Vertebrate Paleontology 44 (1): e2382822; doi: 10.1080\/02724634.2024.2382822<\/p>\n","protected":false},"excerpt":{"rendered":"Paleontologists have identified a new species of rodent in Acarechimys, an extinct genus with a widespread South American…\n","protected":false},"author":2,"featured_media":66323,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[77],"tags":[46504,46505,46506,377,46507,18,4696,19,17,46508,46509,46510,46511,46512,46513,133,46514,13647,19447],"class_list":{"0":"post-66322","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-acarechimys","9":"tag-acarechimys-hunikuini","10":"tag-amazonia","11":"tag-brazil","12":"tag-caviomorpha","13":"tag-eire","14":"tag-fossil","15":"tag-ie","16":"tag-ireland","17":"tag-jaw","18":"tag-mammal","19":"tag-miocene","20":"tag-octochinchilloi","21":"tag-octodontoidea","22":"tag-rodent","23":"tag-science","24":"tag-solimoes-formation","25":"tag-south-america","26":"tag-teeth"},"share_on_mastodon":{"url":"","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/66322","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=66322"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/66322\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/66323"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=66322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=66322"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=66322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}