Turnover in burrowing rodents: The roles of competition and habitat change

Studies of the biostratigraphy and palaeoecology of fossil vertebrate assemblages require large samples of accurately identified specimens. Such analyses can be hampered by the inability to assign isolated and worn remains to specific taxa. Entoptychine gophers are a diverse group of burrowing rodents found in Oligo‐Miocene deposits of the western United States. In both entoptychines and their extant relatives the geomyines, diagnostic characters of the occlusal surface of the teeth are modified with wear, making difficult the identification of many isolated fossil teeth. We use geometric morphometrics to test the hypothesis that tooth shape informs taxonomic affinities and expected levels of morphological variation across gopher taxa. We also incorporate data from microcomputer tomography to investigate changes in occlusal surface shape through wear within individuals. Our analyses demonstrate the usefulness of our approach in identifying extant geomyines to the genus, subgenus and species levels, and fossil entoptychines to the genus and, in some cases, the species level. Our results cast doubt on the validity of some species within Entoptychus and suggest future revisions to entoptychine taxonomy. The amounts of morphological divergence observed among fossil and extant genera are similar. Fossil species do not differ greatly from extant ones in that regard either. Further work evaluating the morphological variation within and across entoptychine species, including unworn teeth and osteological material, will allow revised analyses of the biostratigraphy and palaeoecology of important Oligo‐Miocene mammalian assemblages of the western United States and help to infer the phylogenetic relationships and evolution of gophers.

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“…; Calede et al . ) require large sample sizes of well‐identified mammalian fossils (Damuth ; Olzewski ; Moore et al . ; Forcino ).…”

Section: Previous Taxonomic Diagnoses Of Gopher Speciesmentioning

confidence: 99%

Geometric morphometric analyses of worn cheek teeth help identify extant and extinct gophers (Rodentia, Geomyidae)

Calede

Glusman

2017

Palaeontology

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“…Although this estimate may not be very accurate because it is derived from an estimate of the body mass of UWBM 113209, which is itself determined from a measurement of the skull length based on a carbonaceous impression, the absence of a preserved tooth row prevents a direct measurement on the specimen. The lower tooth row length estimate (Table 1) (Calede et al 2011, Shotwell 1958 and overlap in size with UWBM 113209 (Calede et al 2011, Hopkins 2007. However, they differ greatly in morphology.…”

Section: Introductionmentioning

confidence: 97%

“…The Inland Northwest of the United States (Idaho, eastern Oregon and Washington, and portions of surrounding states) is a natural laboratory for the study of the MMCO due not only to the detailed paleoclimatic (Retallack 2007, Retallack 2009, Takeuchi et al 2007, Yang et al 2011) and paleoenvironmental (Bestland et al 2008, Harris et al 2017, Kohn and Fremd 2007, Sheldon 2003 records available in the region but also to the wealth of terrestrial fossil floras and faunas preserved there. These include the vertebrate faunas of the Mascall (Downs 1956, Maguire et al 2018), Sucker Creek (Scharf 1935, and Virgin Valley formations (Merriam 1911), which, along with other localities in the region, have served as the basis for several analyses of vertebrate macroecology (e.g., Badgley and Finarelli 2013, Calede et al 2011, Harris 2016, Maguire 2015, Orcutt and Hopkins 2013.…”

Section: Introductionmentioning

confidence: 99%

“…Comparison-Although most of the detailed morphology of the skeleton of UWBM 113209 cannot be described and the teeth are fragmented, the size of the specimen as well as elements of its dentition allow the taxonomic identity of UWBM 113209 to be constrained. Based on skull length, we estimate the body mass of the animal at around 492 g (using the regression formula even North America as a whole, did (Barnosky et al 2007, Calede et al 2011, Munthe 1977).…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, both Liodontia and Tardontia display typical derived aplodontiid hypsodont dentitions (Flynn and Jacobs 2008a, Gazin 1932, Hopkins 2008a, Shotwell 1958) that are quite unlike the bunodont-brachydont dentition of UWBM 113209. Although a diverse fauna of mylagaulids is known from the Inland Northwest (Barnosky et al 2007, Calede and Hopkins 2012a, Calede et al 2011, most genera are much larger than UWBM 113209 (Calede et al 2011). Only the genus Mesogaulus is similar in size to UWBM 113209 (Dorr 1956, Hopkins 2007.…”

Section: Introductionmentioning

confidence: 99%

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Peer Review #1 of "The first tetrapod from the mid-Miocene Clarkia lagerstätte (Idaho, USA) (v0.1)"

Hanson¹

2018

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The Clarkia lagerstätte (Latah Formation) of Idaho is well known for its beautifully preserved plant fossils as well as a fauna of insects and fish. Here we present the first known tetrapod fossil from these deposits. This specimen, recovered from the lower anoxic zone of the beds, is preserved as a carbonaceous film of a partial skeleton associated with a partial lower incisor and some tooth fragments. The morphology of the teeth indicates that the first tetrapod reported from Clarkia is a rodent. Its skeletal morphology as well as its bunodont and brachydont dentition suggests that it is a member of the squirrel family (Sciuridae). It is a large specimen that cannot be assigned to a known genus. 18 from these deposits. This specimen, recovered from the lower anoxic zone of the beds, is 19 preserved as a carbonaceous film of a partial skeleton associated with a partial lower incisor and 20 some tooth fragments. The morphology of the teeth indicates that the first tetrapod reported from 21 Clarkia is a rodent. Its skeletal morphology as well as its bunodont and brachydont dentition 22 suggests that it is a member of the squirrel family (Sciuridae). It is a large specimen that cannot 23 be assigned to a known genus. Instead, it appears to represent the first occurrence of a new taxon 24 with particularly gracile postcranial morphology likely indicative of an arboreal ecology. This 25 new specimen is a rare glimpse into the poorly known arboreal mammal fossil record of the 26 Neogene. It supports a greater taxonomic and ecological diversity of Miocene Sciuridae than 27 previously recognized and offers new lines of inquiry in the paleoecological research enabled by 28 the unique preservation conditions of the Clarkia biota.

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Locomotory adaptations in entoptychine gophers (Rodentia: Geomyidae) and the mosaic evolution of fossoriality

Calede

Samuels

Chen

2019

Journal of Morphology

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Pocket gophers (family Geomyidae) are the dominant burrowing rodents in North America today. Their fossil record is also incredibly rich; in particular, entoptychine gophers, a diverse extinct subfamily of the Geomyidae, are known from countless teeth and jaws from Oligocene and Miocene-aged deposits of the western United States and Mexico. Their postcranial remains, however, are much rarer and little studied. Yet, they offer the opportunity to investigate the locomotion of fossil gophers, shed light on the evolution of fossoriality, and enable ecomorphological comparisons with contemporaneous rodents. We present herein a quantitative study of the cranial and postcranial remains of eight different species of entoptychine gophers as well as many contemporary rodent species. We find a range of burrowing capabilities within Entoptychinae, including semifossorial scratch-digging animals and fossorial taxa with cranial adaptations to burrowing. Our results suggest the repeated evolution of chisel-tooth digging across genera. Comparisons between entoptychine gophers and contemporaneous rodent taxa show little ecomorphological overlap and suggest that the succession of burrowing rodent taxa on the landscape may have had more to do with habitat partitioning than competition. K E Y W O R D S burrowing, Castoridae, ecomorphology, functional morphology, Heteromyidae, resource partitioning

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Turnover in burrowing rodents: The roles of competition and habitat change

Cited by 22 publications

References 79 publications

Geometric morphometric analyses of worn cheek teeth help identify extant and extinct gophers (Rodentia, Geomyidae)

Geometric morphometric analyses of worn cheek teeth help identify extant and extinct gophers (Rodentia, Geomyidae)

Peer Review #1 of "The first tetrapod from the mid-Miocene Clarkia lagerstätte (Idaho, USA) (v0.1)"

Locomotory adaptations in entoptychine gophers (Rodentia: Geomyidae) and the mosaic evolution of fossoriality

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