Paleontologists have recognized a brand new species of rodent in Acarechimys, an extinct genus with a widespread South American distribution, from a partial jaw and enamel unearthed in Brazil.
Hypothetical reconstruction of Acarechimys hunikuini. Picture credit score: Márcio Castro.
Acarechimys hunikuini lived in what’s now Brazilian Amazonia round 10 million years in the past (Late Miocene epoch).
The traditional species belongs to Octodontoidea, a household of Neotropical hystricognathous rodents throughout the parvorder Caviomorpha.
“Hystricognathous rodents of the Neotropics, i.e., Caviomorpha, are an enchanting mammal group due to their astonishing taxonomic and ecological variety, which displays a posh evolutionary historical past,” mentioned Dr. Emmanuelle Fontoura, a paleontologist with the Universidade Federal de Santa Maria and CAPPA-Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, and colleagues.
“These rodents seem all of the sudden within the South American fossil document on the finish of the Eocene epoch, no less than from what we all know from the accessible document, particularly that of Peruvian Amazonia.”
“By the Early Oligocene, that they had already diversified, with the primary representatives of the crown teams.”
“Current‐day caviomorphs comprise 266 species, structured into two main clades and 4 superfamilies: i) Erethicavioi grouping Cavioidea (e.g., guinea pig and associated kinds) and Erethizontoidea (New World porcupines), and ii) Octochinchilloi with Chinchilloidea (chinchilla and pacaranas) and Octodontoidea (e.g., spiny rats and associated kinds).”
“The superfamily Octodontoidea consists of the extant households Abrocomidae, Echimyidae, Octodontidae and Ctenomyidae, plus extinct lineages.”
“That is the richest and most various clade amongst Caviomorpha, each taxonomically and phenotypically by way of time.”
The dental stays of Acarechimys hunikuini have been collected throughout subject journeys in 2019 and 2022 on the PRE06 outcrop of the Solimões Formation close to town of Feijó within the Brazilian state of Acre.
“The Solimões Formation has yielded an awesome variety of vertebrate fossils because the mid‐nineteenth century,” the paleontologists mentioned.
“Fossil‐bearing localities from this formation have been not too long ago dated, revealing most ages of deposition throughout the Tortonian, i.e., Higher Miocene.”
“Mammals are among the many most various fossils discovered there, together with bats, cetaceans, litopterns, marsupials, notoungulates, primates, rodents, sirenians, and xenarthrans.”
“As well as, fossil stays of birds, crocodilians, chelonians, fishes, amphibians, invertebrates, ichnofossils, and vegetation have additionally been documented.”
The invention of Acarechimys hunikuini exhibits that a number of superfamilies of caviomorphous rodents co-existed on this area, along with many different animal teams, highlighting the existence of a wealthy fauna within the Brazilian Amazonia.
“Acarechimys presumably emerged throughout the Late Oligocene and diversified within the Patagonian area throughout the Early Miocene,” the researchers mentioned.
“Through the Center Miocene, it unfold to additional‐Patagonian areas, in the direction of the north of South America.”
“Through the Late Miocene, the lineage remained solely in additional‐Patagonian areas.”
“This new document, which is the final look of the genus, helps the speculation of the late survival of rodent lineages within the tropics, a sample that has been documented in octodontoids, hydrochoerines and neoepiblemids.”
“The fast diversification and radiation of Acarechimys, in addition to the shortage of information, divergence of opinions between research devoted to this group, and the various remoted enamel reported for the Amazonian area, make the analysis of this genus difficult.”
“Additional analysis is required to reinforce our comprehension of the diversification and temporal variation of this broad lineage of Octodontoidea.”
The group’s paper was printed within the Journal of Vertebrate Paleontology.
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Emmanuelle Fontoura et al. 2024. A brand new Late Miocene stem Octodontoid (Rodentia: Caviomorpha: Octochinchilloi) from the Solimões Formation (Brazil): paleobiogeographic implications. Journal of Vertebrate Paleontology 44 (1): e2382822; doi: 10.1080/02724634.2024.2382822
