New material of<i>Alphagaulus pristinus</i>(Mammalia, Rodentia, Mylagaulidae) from the Deep River Formation (Montana, U.S.A.): Implications for ecology, ontogeny, and phylogeny

Calede, Jonathan J.; Hopkins, Samantha S. B.

doi:10.1080/02724634.2012.634356

Cited by 18 publications

(14 citation statements)

References 21 publications

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“…Finally, a recent study on palaeocastorine beavers (Rodentia, Castoridae), which are members of the burrowing fauna of the Oligocene of North America, showed that some morphological changes in crania and postcrania throughout ontogeny may be associated with increased burrowing ability in adults, probably as a consequence of greater burrowing needs with increased size (Calede, in press; and references therein). The data presented by Calede (in press) can be compared to those described by Calede and Hopkins () for an early mylagaulid (Rodentia, Aplodontoidea, Mylagaulidae, Alphagualus pristinus ) supporting greater adaptations to fossoriality in the forearm of the mylagaulid than in the paleocastorine. This description of A. pristinus gave insights into the ontogeny of these burrowing mammals, suggesting that the developmental trajectory mimics evolution in the increase of fossorial modifications of the skeleton with time (Calede and Hopkins, ; see also Vassallo and Mora, ; Verzi et al, ).…”

Section: Discussionmentioning

confidence: 86%

“…The data presented by Calede (in press) can be compared to those described by Calede and Hopkins () for an early mylagaulid (Rodentia, Aplodontoidea, Mylagaulidae, Alphagualus pristinus ) supporting greater adaptations to fossoriality in the forearm of the mylagaulid than in the paleocastorine. This description of A. pristinus gave insights into the ontogeny of these burrowing mammals, suggesting that the developmental trajectory mimics evolution in the increase of fossorial modifications of the skeleton with time (Calede and Hopkins, ; see also Vassallo and Mora, ; Verzi et al, ). As Calede (in press) stated, common trends in the ontogeny of these two burrowing groups (i.e., paleocastorines and mylagaulids) relate to convergence in scratch‐digging behavior and include changes in the proportion and development of forelimb traits.…”

Section: Discussionmentioning

confidence: 86%

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Postnatal ontogeny of limb proportions and functional indices in the subterranean rodentCtenomys talarum(Rodentia: Ctenomyidae)

Echeverría

Becerra

Vassallo

2014

Journal of Morphology

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Burrow construction in the subterranean Ctenomys talarum (Rodentia: Ctenomyidae) primarily occurs by scratch-digging. In this study, we compared the limbs of an ontogenetic series of C. talarum to identify variation in bony elements related to fossorial habits using a morphometrical and biomechanical approach. Diameters and functional lengths of long bones were measured and 10 functional indices were constructed. We found that limb proportions of C. talarum undergo significant changes throughout postnatal ontogeny, and no significant differences between sexes were observed. Five of six forelimb indices and two of four hindlimb indices showed differences between ages. According to discriminant analysis, the indices that contributed most to discrimination among age groups were robustness of the humerus and ulna, relative epicondylar width, crural and brachial indices, and index of fossorial ability (IFA). Particularly, pups could be differentiated from juveniles and adults by more robust humeri and ulnae, wider epicondyles, longer middle limb elements, and a proportionally shorter olecranon. Greater robustness indicated a possible compensation for lower bone stiffness while wider epicondyles may be associated to improved effective forces in those muscles that originate onto them, compensating the lower muscular development. The gradual increase in the IFA suggested a gradual enhancement in the scratch-digging performance due to an improvement in the mechanical advantage of forearm extensors. Middle limb indices were higher in pups than in juveniles-adults, reflecting relatively more gracile limbs in their middle segments, which is in accordance with their incipient fossorial ability. In sum, our results show that in C. talarum some scratch-digging adaptations are already present during early postnatal ontogeny, which suggests that they are prenatally shaped, and other traits develop progressively. The role of early digging behavior as a factor influencing on morphology development is discussed.

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 86%

Postnatal ontogeny of limb proportions and functional indices in the subterranean rodentCtenomys talarum(Rodentia: Ctenomyidae)

Echeverría

Becerra

Vassallo

2014

Journal of Morphology

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“…They are typically very large, high-crowned, and display a complex occlusal surface composed of enamel lakes Hopkins 2012a, Shotwell 1958). The postcranial skeleton of UWBM 113209 provides additional evidence that the Clarkia rodent is not a mylagaulid, given its gracile forelimbs unlike those found in mylagaulids (Calede and Hopkins 2012b, Fagan 1960, Galbreath 1984, Korth 2000.…”

Section: Introductionmentioning

confidence: 99%

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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“…There are numerous characters in Al. pristinus that change throughout ontogeny including the shape and size of the infraorbital foramen and zygomatic arch, the height of occipital and sagittal crests, and the size and position of the postorbital processes (Calede & Hopkins, 2012). The overall similarity in these cranial features between the two specimens of H. gazini examined and the fact that both specimens have a fully adult dentition (even though some teeth are missing from the JODA specimen) suggest that the JODA specimen is a young adult, not a juvenile.…”

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confidence: 99%

“…The ontogenetic pattern of skull morphology seen in H. gazini is similar to that described for Al. pristinus (Calede & Hopkins, 2012). The angle of the occipital plate mentioned by Gazin (1932) and Korth (1999) also changes throughout the development of an individual.…”

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confidence: 99%

Intraspecific versus interspecific variation in Miocene Great Basin mylagaulids: implications for systematics and evolutionary history

Calede

Hopkins

2012

Zoological Journal of the Linnean Society

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The Mylagaulidae are a family of burrowing rodents abundant in Miocene faunas from western North America. Recent taxonomic revisions of mylagaulids from the Great Plains suggest that their systematics may be best understood on a regional basis. Previous studies addressed the taxonomy and evolutionary history of mylagaulids from the Great Basin, but recent discoveries of specimens, new phylogenetic data, and more detailed stratigraphical information necessitate a thorough reanalysis of their relationships and occurrences. We present a revision of the systematics of the mylagaulids from the Great Basin. In addition to rare large mylagaulids of uncertain taxonomic affinity, we recognize four species of mylagaulids distributed throughout Oregon and Nevada from the late Hemingfordian through to the early late Hemphillian: Alphagaulus vetus, Hesperogaulus gazini, Hesperogaulus wilsoni, and a new species from the genus Hesperogaulus. All species are known from large sample sizes of isolated premolars, allowing consideration of ontogenetic variation in determining the key morphological differences that allow recognition of different species. Although the number of enamel lakes varies within a given taxon, the presence of some of these lakes is taxonomically significant. This result emphasizes the importance of understanding ontogeny in describing species of fossil hypsodont mammals.

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New material ofAlphagaulus pristinus(Mammalia, Rodentia, Mylagaulidae) from the Deep River Formation (Montana, U.S.A.): Implications for ecology, ontogeny, and phylogeny

Cited by 18 publications

References 21 publications

Postnatal ontogeny of limb proportions and functional indices in the subterranean rodentCtenomys talarum(Rodentia: Ctenomyidae)

Postnatal ontogeny of limb proportions and functional indices in the subterranean rodentCtenomys talarum(Rodentia: Ctenomyidae)

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

Intraspecific versus interspecific variation in Miocene Great Basin mylagaulids: implications for systematics and evolutionary history

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