1
|
Oliveira ÉV, Carneiro LM, Goin FJ. A new derorhynchid (Mammalia, Metatheria) from the early Eocene Itaboraí fauna of Brazil with comments on its affinities. AN ACAD BRAS CIENC 2021; 93:e20201554. [PMID: 34378646 DOI: 10.1590/0001-3765202120201554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/22/2021] [Indexed: 11/22/2022] Open
Abstract
A new early Eocene, small-sized metatherian from the Itaboraí fauna is described. The new taxon is recognized on the basis of an incomplete dentary recovered from fissure fillings in the travertine limestones from the Itaboraí Basin, State of Rio de Janeiro, Brazil. The phylogenetic analysis placed the new genus and species as the sister taxon of Derorhynchus, undescribed Derorhynchidae, and Coona plus Pauladelphys. When compared to Derorhynchus, the new taxon exhibits a shorter dentary, in which the first lower premolar is not separated from the second by a diastema, and shows second and third lower molars with subequal trigonid and talonid width (in Derorhynchus the talonids are wider than the trigonids). This new taxon shows some plesiomorphic traits when compared with the remaining derorhynchids, such as the shallower dentary (less than 1.5 mm), and conical entoconids rather than flattened in shape. The combination of very small size (~13-20g), sharp crests, tall and slender cuspids, broad talonid basins, as well as trigonid taller than the talonid is suggestive of an insectivorous diet for the new taxon.
Collapse
Affiliation(s)
- Édison Vicente Oliveira
- PPGEOC, Programa de Pós-Graduação em Geociências, Departamento de Geologia, Centro de Tecnologia e Geociências, Universidade Federal de Pernambuco, Av. Acadêmico Hélio Ramos, s/n, Cidade Universitária, 50740-530, Recife, PE, Brazil.,Paleolab, Laboratório de Paleontologia, Departamento de Geologia, Centro de Tecnologia e Geociências, Universidade Federal de Pernambuco, Av. Acadêmico Hélio Ramos, s/n, Cidade Universitária, 50740-530, Recife, PE, Brazil
| | - Leonardo M Carneiro
- PPGEOC, Programa de Pós-Graduação em Geociências, Departamento de Geologia, Centro de Tecnologia e Geociências, Universidade Federal de Pernambuco, Av. Acadêmico Hélio Ramos, s/n, Cidade Universitária, 50740-530, Recife, PE, Brazil.,Laboratório de Paleontologia e Paleoecologia da Sociedade de História Natural, Travessa Florêncio Augusto Chagas nº 8B, 2560-230 Torres Vedras, Portugal
| | - Francisco J Goin
- División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Paseo del Bosque, s/n, B1900FWA La Plata, Argentina
| |
Collapse
|
2
|
Harper T, Rougier GW. Petrosal morphology and cochlear function in Mesozoic stem therians. PLoS One 2019; 14:e0209457. [PMID: 31412094 PMCID: PMC6693738 DOI: 10.1371/journal.pone.0209457] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 06/07/2019] [Indexed: 11/19/2022] Open
Abstract
Here we describe the bony anatomy of the inner ear and surrounding structures seen in three plesiomorphic crown mammalian petrosal specimens. Our study sample includes the triconodont Priacodon fruitaensis from the Upper Jurassic of North America, and two isolated stem therian petrosal specimens colloquially known as the Höövör petrosals, recovered from Aptian-Albian sediments in Mongolia. The second Höövör petrosal is here described at length for the first time. All three of these petrosals and a comparative sample of extant mammalian taxa have been imaged using micro-CT, allowing for detailed anatomical descriptions of the osteological correlates of functionally significant neurovascular features, especially along the abneural wall of the cochlear canal. The high resolution imaging provided here clarifies several hypotheses regarding the mosaic evolution of features of the cochlear endocast in early mammals. In particular, these images demonstrate that the membranous cochlear duct adhered to the bony cochlear canal abneurally to a secondary bony lamina before the appearance of an opposing primary bony lamina or tractus foraminosus. Additionally, while corroborating the general trend of reduction of venous sinuses and plexuses within the pars cochlearis seen in crownward mammaliaforms generally, the Höövör petrosals show the localized enlargement of a portion of the intrapetrosal venous plexus. This new vascular feature is here interpreted as the bony accommodation for the vein of cochlear aqueduct, a structure that is solely, or predominantly, responsible for the venous drainage of the cochlear apparatus in extant therians. Given that our fossil stem therian inner ear specimens appear to have very limited high-frequency capabilities, the development of these modern vascular features of the cochlear endocast suggest that neither the initiation or enlargement of the stria vascularis (a unique mammalian organ) was originally associated with the capacity for high-frequency hearing or precise sound-source localization.
Collapse
Affiliation(s)
- Tony Harper
- Center for Functional Anatomy and Evolution, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Guillermo W. Rougier
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, United States of America
| |
Collapse
|
3
|
Eldridge MDB, Beck RMD, Croft DA, Travouillon KJ, Fox BJ. An emerging consensus in the evolution, phylogeny, and systematics of marsupials and their fossil relatives (Metatheria). J Mammal 2019. [DOI: 10.1093/jmammal/gyz018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Mark D B Eldridge
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | - Robin M D Beck
- School of Environment and Life Sciences, University of Salford, Manchester, United Kingdom
| | - Darin A Croft
- School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | | | - Barry J Fox
- School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
| |
Collapse
|
4
|
Engelman RK, Flynn JJ, Gans P, Wyss AR, Croft DA. Chlorocyon phantasma, a Late Eocene Borhyaenoid (Mammalia: Metatheria: Sparassodonta) from the Los Helados Locality, Andean Main Range, Central Chile. AMERICAN MUSEUM NOVITATES 2018. [DOI: 10.1206/3918.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
| | - John J. Flynn
- Division of Paleontology and Richard Gilder Graduate School, American Museum of Natural History, New York
| | - Philip Gans
- Department of Earth Science, University of California, Santa Barbara, California
| | - André R. Wyss
- Department of Earth Science, University of California, Santa Barbara, California
| | - Darin A. Croft
- Department of Anatomy, Case Western Reserve University, Cleveland, Ohio
| |
Collapse
|