Detrital zircon U–Pb geochronology constrains the age of Brazilian Neogene deposits from Western Amazonia

The rodent Neoepiblema acreensis (Chinchilloidea: Neoepiblemidae) is member of a lineage that reached gigantic dimensions during the Late Miocene of South America-the Neoepiblemidae. In this paper, the cranial anatomy of this rodent is reviewed. Noninvasive imaging is used to reveal internal structures. Our review is based mainly on an almost complete cranium from the Upper Miocene deposits of the western Amazonia of Brazil. The cranium has an elongated rostrum, large frontal sinuses, a deep temporal fossa, well-developed sagittal, nuchal, medial occipital, and secondary crests, and a tympanic fenestra connected to the external acoustic meatus by a thin ventral cleft. Remarkably, the cranium shows the presence of fossae on the posterior region of the frontal and parietal bones, and a "W-shaped" fronto-parietal suture, which are not present in other analyzed chinchilloids. This study contributes to the knowledge of the morphology of this extinct rodent as well as to the phylogenetic relationships and paleobiology of neoepiblemids.

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“…Niterói locality, Acre River, Acre, Brazil. Maximum age of deposition: detrital zircon U–Pb age 8.5 ± 0.5 Ma (Bissaro‐Júnior et al, ).…”

Section: Resultsmentioning

confidence: 99%

A reassessment of the cranial morphology of Neoepiblema acreensis (Rodentia: Chinchilloidea), a Miocene rodent from South America

Kerber

Ferreira

2019

Journal of Morphology

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“…Both fossil specimens used in this study came from the Acre Basin, a retroarc foreland basin related to the Andean orogenesis [ 27 ]. It is the westernmost of a series of interior sag/fracture basins along the Solimões/Amazonas rivers, at the westernmost portion of the Brazilian Amazon, neighboring Peru and Bolivia [ 28 , 29 , 30 ]. They were collected in the sedimentary deposits of the Late Miocene Solimões Formation, which is mostly exposed along riverbanks in the states of Acre and Amazonas.…”

Section: Materials and Methodsmentioning

confidence: 99%

Structure and Chemical Composition of ca. 10-Million-Year-Old (Late Miocene of Western Amazon) and Present-Day Teeth of Related Species

Pessoa-Lima

Tostes-Figueiredo

Macedo-Ribeiro

et al. 2022

Biology

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Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: Purussaurus sp. (extinct) and Melanosuchus niger (extant), and Rodentia: Neoepiblema sp. (extinct) and Hydrochoerus hydrochaeris (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel’s physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

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“…In the Acre region, this Formation is made up of fluvial depositional environments (floodplain lakes, paleosoils). The age of the total thickness and deepest levels of the Solimões Formation is not well known, but the fossiliferous uppermost levels cropping out in Western Brazilian Amazon were assigned to the Late Miocene (Latrubesse et al 2007;2010;Bissaro-Júnior et al 2019).…”

Section: Study Areamentioning

confidence: 99%

Sporepolinic morphology of fluvial terrace sediments in the Western Amazon

et al. 2020

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Morphological descriptions were made for pollen grains and spores extracted from samples from three sedimentary sections-Chandless 1, Purus 10 and Purus 30-from fluvial terraces on the Chandless and Purus rivers, Acre State, Brazil. Level CH1-12 at Chandless 1 was C 14-dated to 4861-5050 cal yr BP, P10-3 of Purus 10 was dated through the OSL method at 8200 +/-65 yr BP, while P30-6 at Purus 30 was C 14 dated to 7845-7998 cal yr BP. For pollen analysis, 2 cm 3 of each sample was removed, treated with potassium hydroxide (KOH) and acetolysed, followed by palymorph separation with bromoform/alcohol density 2.0 solution. A total of 49 palynomorphs were morphologically described (39 pollen types and 10 Pteridophyte spores). The most frequent pollen types belonged to Anacardiaceae, Arecaceae, Euphorbiaceae, Fabaceae, Rutaceae and Amaranthaceae, while the most frequent spores belonged to Polypodiaceae and Pteridaceae. The pollen richness found in the studied samples reflects the current vegetation occupying the banks of the rivers.

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Detrital zircon U–Pb geochronology constrains the age of Brazilian Neogene deposits from Western Amazonia

Cited by 35 publications

References 45 publications

A reassessment of the cranial morphology of Neoepiblema acreensis (Rodentia: Chinchilloidea), a Miocene rodent from South America

A reassessment of the cranial morphology of Neoepiblema acreensis (Rodentia: Chinchilloidea), a Miocene rodent from South America

Structure and Chemical Composition of ca. 10-Million-Year-Old (Late Miocene of Western Amazon) and Present-Day Teeth of Related Species

Sporepolinic morphology of fluvial terrace sediments in the Western Amazon

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