[dinosaur] Upper canine replacement in sabertooth carnivores + marsupial tails

Ben Creisler
[email protected]


Some recent non-dino mammal papers that may be of interest:

Free pdf:

Matthew Aleksander Wysocki (2019)
Fossil evidence of evolutionary convergence in juvenile dental morphology
and upper canine replacement in sabertooth carnivores
Ecology and Evolution (advance online publication)
doi:  https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1002_ece3.5732&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=tlQOF5sOqNCzvl6VoVYIBqdyCjvUI-c8YDQH6gSxsi0&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_10.1002_ece3.5732&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=_grd6rTI9-Sh4S8SOUhJvqm0cYQRulNJShvX96Cd7So&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_pdf_10.1002_ece3.5732&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=9jamihe4iPaXqQo5a-WNb0bL0PqnD0JAkdp-Uh19SbQ&e= 

The convergent suite of morphological traits characterizing the mammalian
sabertooth ecomorphology is well documented, including modifications of the
dental and osteological portions of the masticatory apparatus from a
less‐specialized carnivore condition. Equally important is how those
specialized adult morphologies developed through ontogeny because previous
studies have shown that growing such specialized craniodental traits may
require evolutionary modification of growth patterns and tooth replacement
mechanisms. Despite the understanding of convergent morphological
specialization in adult sabertooth carnivores, the possibility of a
convergent ontogenetic trajectory toward those adult morphologies has not
been rigorously examined. The present study examines numerous previously
undescribed juvenile nimravid specimens. The results provide insights about
nimravid ontogeny and show, for the first time, that the nimravid
sabertooth lineage included species in which the permanent upper canine
erupted within a lingual concavity of the deciduous upper canine until it
reached comparable crown height beyond the alveolar border. Furthermore,
this investigation assesses the juvenile morphology and upper canine
replacement of felid and barbourofelid sabertooth taxa. The results provide
evidence of convergence in deciduous upper canine morphology of three
sabertooth carnivore lineages (i.e., nimravid, felid, and barbourofelid),
as well as preliminary evidence of convergence in the upper canine
replacement process. It might be beneficial for studies of extreme
morphological specialization to simultaneously consider convergence in
adult morphologies and how morphologies change through ontogeny.

========
Also, paywalled:


Meg L. Martin,  Kenny J. Travouillon,  Emma Sherrat,t  Patricia A. Fleming
 & Natalie M. Warburton (2019)
Covariation between forelimb muscle anatomy and bone shape in an Australian
scratch‐digging marsupial: Comparison of morphometric methods.
Journal of Morphology (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1002_jmor.21074&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=ymTqtPPQe64Xaw5txqoeD3P6ZpQbG3Ydy-IYflORd6M&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_10.1002_jmor.21074&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=qbVEqcrsiD07bhZ8Cz8WeRgVp6aOS78hxNe0E3b6rog&e= 

The close association between muscle and bone is broadly intuitive;
however, details of the covariation between the two has not been
comprehensively studied. Without quantitative understanding of how muscle
anatomy influences bone shape, it is difficult to draw conclusions of the
significance of many morphological traits of the skeleton. In this study,
we investigated these relationships in the Quenda (Isoodon fusciventer), a
scratch‐digging marsupial. We quantified the relationships between forelimb
muscle anatomy and bone shape for animals representing a range of body
masses (124–1,952 g) using two‐block partial least square analyses. Muscle
anatomy was quantified as muscle mass and physiological cross‐sectional
area (PCSA), and we used two morphometric methods to characterize bone
shape: seven indices of linear bone proportions, and landmarks analysis.
Bone shape was significantly correlated with body mass, reflecting
allometric bone growth. Of the seven bone indices, only shoulder moment
index (SMI) and ulna robustness index (URI) showed a significant
covariation with muscle anatomy. Stronger relationships between muscle
anatomy and forelimb bone shape were found using the landmark coordinates:
muscle mass and PCSA were correlated with the geometric shape of the
scapula, humerus, and third metacarpal, but to a lesser extent with shape
of the ulna. Overall, our data show that landmark coordinates are more
sensitive than bone indices to capturing shape changes evident throughout
ontogeny, and is therefore a more appropriate method to investigate
covariation with forelimb muscle anatomy. Single‐species studies
investigating ontogeny require refined methods to accurately develop
understanding of the important relationships between muscle force
generation and bone shape remodeling. Landmark analyses provide such a
method.

====


Vera Weisbecker, Cruise Speck & Andrew M. Baker (2019)
A tail of evolution: evaluating body length, weight and locomotion as
potential drivers of tail length scaling in Australian marsupial mammals.
Zoological Journal of the Linnean Society, zlz055 (advance online
publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1093_zoolinnean_zlz055&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=0yQhQKT2a7hVN1QcMETPyKZxzIxMANu1urDDvLQ4zbs&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__academic.oup.com_zoolinnean_advance-2Darticle-2Dabstract_doi_10.1093_zoolinnean_zlz055_5602649&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=rVa1Sj2OBdjnrVGel9oNe1fijsRR8VMQTHqKpUiu0JE&s=FNBZ6GVDmUElcbej3wBknPkXnjzxCLzEFW3OPKEOr4E&e= 


Although mammalian tail length relative to body length is considered
indicative of locomotor mode, this association has been difficult to
quantify. This could be because the counterweight function of the tail
might associate it more with body weight than body length. Alternatively,
relative tail length might not be evolutionarily flexible owing to its
integration with the remaining skeleton, particularly the spine. Using
comparative analyses of morphological means and ranges in Australian
marsupials, including the first co-assessment with body weight, our study
supports the second hypothesis, i.e. tail length ranges within species, and
tail lengths among species are explained better by body length than by body
weight. However, all three variables do not differ in phylogenetic signal
or rates of evolution. Associations of tail lengths with locomotion are
limited, but suggest that scaling slopes, rather than intercepts, are
responsible for limited divergence between relative tail lengths at
different locomotor modes. This complicates (palaeo-)ecological
interpretations of tail length further. We conclude that relative tail
length is not a strong predictor of locomotor mode, probably owing to
strong integration of tail and body length. The many well-documented bony
and soft-tissue adaptations of tails are likely to be better suited to
interpretations of locomotor adaptations.



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