Dataset Information

Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor.

ABSTRACT: The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis and the genus Propalaeocastor, based on newly discovered specimens from the Irtysh River Formation. The dental morphology of P. irtyshensis is very similar to other early castorids. The caudal palatine foramen of P. irtyshensis is situated in the maxillary-palatine suture. This is a feature generally accept as diagnostic character for the castorids. On the other hand, P. irtyshensis has two upper premolars, a rudimentarily developed sciuromorph-like zygomatic plate, and a relatively large protrogomorph-like infraorbital foramen. Some previous researchers suggested that Propalaeocastor is a junior synonym of Steneofiber, while other took it as a valid genus. Our morphological comparison and phylogenetic analysis suggest that Propalaeocastor differs from Steneofiber and is a valid genus. We also suggest that Agnotocastor aubekerovi, A. coloradensis, A. galushai, A. readingi, Oligotheriomys primus, and "Steneofiber aff. dehmi" should be referred to Propalaeocastor. Propalaeocastor is the earliest and most basal beaver. The origin place of Propalaeocastor and castorids is uncertain. The Early Oligocene radiation of castorids probably is propelled by the global climate change during the Eocene-Oligocene transition.

SUBMITTER: Li L

PROVIDER: S-EPMC5436589 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor.

Li Lüzhou L Li Qiang Q Lu Xiaoyu X Ni Xijun X

PeerJ 20170516

The Early to Late Oligocene Propalaeocastor is the earliest known beaver genus from Eurasia. Although many species of this genus have been described, these species are defined based on very fragmentary specimens. Propalaeocastor irtyshensis from the Early Oligocene Irtysh River Formation in northwestern Xinjiang, China is one of the earliest-known members of Propalaeocastor. This species is defined on a single maxillary fragment. We revise the diagnosis of P. irtyshensis< ...[more]

PMID: 28533963

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Project description:Quantifying the presence and environmental impact of invasive species is the starting point for research on management and nature conservation. North American beavers (Castor canadensis) were introduced to Argentina from Canada in 1946, and the species has been identified as a major agent of environmental change in the Tierra del Fuego archipelago in the Anthropocene. We studied the invasion status (distribution and density) of beavers through analyses of the dam densities in the Tierra del Fuego landscapes. We identified beaver dams with a GIS using visual interpretation of high-resolution aerial imagery from Microsoft Bing, Google Earth and HERE and related them to natural environmental gradients. These factors comprised geographic (vegetation zones and distance to streams), climatic (temperature, precipitation, evapotranspiration and net primary productivity) and topographic (elevation and slope) data. The datasets (dams and factors) were combined, and the data from the different zonation classes were subsequently compared using ANOVAs and Tukey's mean comparison tests. Deviations from the mean density (x mean density-x total mean density) were calculated to visualize the deviations for the studied factors. The datasets were also evaluated using principal component analyses (PCA). Our results showed a total of 206,203 beaver dams (100,951 in Argentina and 105,252 in Chile) in the study area (73,000 km2). The main island of Tierra del Fuego presented a greater degree of invasion (73.6% of the total study area) than the rest of the archipelago, especially in areas covered by mixed-evergreen and deciduous forests. The studied geographic, climatic and topographic factors showed positive trends (higher beaver preference) with beaver spread, which were all significant (p <0.05) when compared across the landscape. Although beavers are flexible in their habitat use, our empirical records showed that they had marked preferences and were positively influenced by the most productive forests. Here, we describe a scientific panorama that identified the drivers of species invasion based on satellite data and the available ecological datasets. The identification of such drivers could be useful for developing new tools for management and/or control strategies of the beavers in the Tierra del Fuego archipelago.

Dataset Information

Morphology of an Early Oligocene beaver Propalaeocastor irtyshensis and the status of the genus Propalaeocastor.

Publications

Morphology of an Early Oligocene beaver <i>Propalaeocastor irtyshensis</i> and the status of the genus <i>Propalaeocastor</i>.

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