@article{dickinson_elminowski_flores_eldridge_granatosky_hartstone-rose_2022, title={A morphological analysis of carnivoran ossicles from Rancho La Brea}, volume={9}, ISSN={["1097-4687"]}, url={https://doi.org/10.1002/jmor.21506}, DOI={10.1002/jmor.21506}, abstractNote={The morphology of the mammalian middle ear-including the size, shape, and stiffness of individual ossicles-controls their vibrational response to sound and, is closely related to an animal's auditory capabilities. While the relationship between middle ear morphology and hearing frequency has been explored in living carnivorans, the size and shape of ossicles in fossil carnivorans have been sparsely documented. In this study, we present the first morphological data on four iconic carnivoran taxa from the Rancho La Brea Tar Pits: Smilodon fatalis, Panthera atrox, Canis dirus, and Arctodus simus. These data are contextualized with samples of extant felids, canids, and ursids to determine the extent to which the ossicles of these iconic fossil taxa resemble their living relatives. Six, five, and seven linear measurements were taken from the malleus, incus, and stapes, respectively. Comparisons of geometric means reveal that the ossicles of fossil canids and felids are similar in size to living analogs, but those of A. simus are significantly larger than those of any living ursid. Further, principal components analyses demonstrate close morphological affinities between fossil and extant taxa within canids and felids, and again, a greater disparity between fossil and extant ursids. Canids and ursids occupy distinct regions of the morphospace, yet both overlap the morphological range spanned by felids. While some elements-for example, the stapes-require further specimens to facilitate more nuanced interpretations of variation, our findings underscore the need for concerted efforts towards identifying and preserving these bones within fossil assemblages.}, journal={JOURNAL OF MORPHOLOGY}, author={Dickinson, Edwin and Elminowski, Erin E. and Flores, Deanna and Eldridge, Emma I and Granatosky, Michael C. and Hartstone-Rose, Adam}, year={2022}, month={Sep} }
 @article{law_blackwell_curtis_dickinson_hartstone-rose_santana_2022, title={Decoupled evolution of the cranium and mandible in carnivoran mammals}, volume={8}, ISSN={["1558-5646"]}, DOI={10.1111/evo.14578}, abstractNote={The relationship between skull morphology and diet is a prime example of adaptive evolution. In mammals, the skull consists of the cranium and the mandible. Although the mandible is expected to evolve more directly in response to dietary changes, dietary regimes may have less influence on the cranium because additional sensory and brain-protection functions may impose constraints on its morphological evolution. Here, we tested this hypothesis by comparing the evolutionary patterns of cranium and mandible shape and size across 100+ species of carnivoran mammals with distinct feeding ecologies. Our results show decoupled modes of evolution in cranial and mandibular shape; cranial shape follows clade-based evolutionary shifts, whereas mandibular shape evolution is linked to broad dietary regimes. These results are consistent with previous hypotheses regarding hierarchical morphological evolution in carnivorans and greater evolutionary lability of the mandible with respect to diet. Furthermore, in hypercarnivores, the evolution of both cranial and mandibular size is associated with relative prey size. This demonstrates that dietary diversity can be loosely structured by craniomandibular size within some guilds. Our results suggest that mammal skull morphological evolution is shaped by mechanisms beyond dietary adaptation alone.}, journal={EVOLUTION}, author={Law, Chris J. and Blackwell, Emily A. and Curtis, Abigail A. and Dickinson, Edwin and Hartstone-Rose, Adam and Santana, Sharlene E.}, year={2022}, month={Aug} }
 @article{leonard_worden_boettcher_dickinson_hartstone-rose_2022, title={Effects of long-term ethanol storage on muscle architecture}, volume={305}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.24638}, DOI={10.1002/ar.24638}, abstractNote={Muscle excursion and force potential can be estimated from architectural variables, including mass, volume, fascicle length, and density. These have been collected from fresh specimens, preserved specimens, and sometimes mixed samples of both. However, preservation alters the gross morphology of muscles. This study aims to quantify the effects of long-term storage on myological properties across a sample of fresh and ethanol preserved Mus musculus specimens ranging in storage time from 16 to 130 years. Masses, volumes, and densities of biceps femoris, quadriceps femoris, and triceps surae were measured, and histological cross-sections of some specimens were used to evaluate the microscale effects of long-term fluid preservation. For the remainder of the sample, chemically dissected fascicle lengths were measured to evaluate the fixation effects on the linear dimensions of muscle architecture. Relative muscle mass, volume, fascicle length, average fiber area, and density, and percent fiber area were regressed against years stored in ethanol. Muscle size dropped steeply between fresh and stored samples, ultimately decreasing by 62 and 60%, respectively. These losses correlate with histologically measured shrinking of average muscle fiber area. Density of stored specimens plateaued 5% below that of fresh ones. Although muscles lost mass and volume during ethanol storage, fascicle lengths did not shorten significantly (presumably because they were preserved attached on either end to bone). This study demonstrates that muscle mass, volume, and density of specimens stored long-term in ethanol should be corrected by factors of 2.64, 2.49, and 1.054 respectively for comparability to fresh specimens.}, number={1}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, publisher={Wiley}, author={Leonard, Kaitlyn C. and Worden, Nikole and Boettcher, Marissa L. and Dickinson, Edwin and Hartstone-Rose, Adam}, year={2022}, month={Jan}, pages={184–198} }
 @article{turcotte_mann_stock_villamil_montague_dickinson_surratt_martinez_williams_anton_et al._2022, title={The ontogeny of sexual dimorphism in free-ranging rhesus macaques}, volume={177}, ISSN={["1096-8644"]}, DOI={10.1002/ajpa.24442}, abstractNote={Reconstructing the social lives of extinct primates is possible only through an understanding of the interplay between morphology, sexual selection pressures, and social behavior in extant species. Somatic sexual dimorphism is an important variable in primate evolution, in part because of the clear relationship between the strength and mechanisms of sexual selection and the degree of dimorphism. Here, we examine body size dimorphism across ontogeny in male and female rhesus macaques to assess whether it is primarily achieved via bimaturism as predicted by a polygynandrous mating system, faster male growth indicating polygyny, or both.We measured body mass in a cross-sectional sample of 364 free-ranging rhesus macaques from Cayo Santiago, Puerto Rico to investigate size dimorphism: 1) across the lifespan; and 2) as an outcome of sex-specific growth strategies, including: a) age of maturation; b) growth rate; and c) total growth duration, using regression models fit to sex-specific developmental curves.Significant body size dimorphism was observed by prime reproductive age with males 1.51 times the size of females. Larger male size resulted from a later age of maturation (males: 6.8-7.8 years versus females: 5.5-6.5 years; logistic model) and elevated growth velocity through the pre-prime period (LOESS model). Though males grew to larger sizes overall, females maintained adult size for longer before senescence (quadratic model).The ontogeny of size dimorphism in rhesus macaques is achieved by bimaturism and a faster male growth rate. Our results provide new data for understanding the development and complexities of primate dimorphism.}, number={2}, journal={AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY}, author={Turcotte, Cassandra M. and Mann, Eva H. J. and Stock, Michala K. and Villamil, Catalina I and Montague, Michael J. and Dickinson, Edwin and Surratt, Samuel Bauman and Martinez, Melween and Williams, Scott A. and Anton, Susan C. and et al.}, year={2022}, month={Feb}, pages={314–327} }
 @article{leonard_worden_boettcher_dickinson_omstead_burrows_hartstone-rose_2021, title={Anatomical and ontogenetic influences on muscle density}, volume={11}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-021-81489-w}, abstractNote={Physiological cross-sectional area (PCSA), an important biomechanical variable, is an estimate of a muscle's contractile force potential and is derived from dividing muscle mass by the product of a muscle's average fascicle length and a theoretical constant representing the density of mammalian skeletal muscle. This density constant is usually taken from experimental studies of small samples of several model taxa using tissues collected predominantly from the lower limbs of adult animals. The generalized application of this constant to broader analyses of mammalian myology assumes that muscle density (1) is consistent across anatomical regions and (2) is unaffected by the aging process. To investigate the validity of these assumptions, we studied muscles of rabbits (Oryctolagus cuniculus) in the largest sample heretofore investigated explicitly for these variables, and we did so from numerous anatomical regions and from three different age-cohorts. Differences in muscle density and histology as a consequence of age and anatomical region were evaluated using Tukey's HSD tests. Overall, we observed that older individuals tend to have denser muscles than younger individuals. Our findings also demonstrated significant differences in muscle density between anatomic regions within the older cohorts, though none in the youngest cohort. Approximately 50% of the variation in muscle density can be explained histologically by the average muscle fiber area and the average percent fiber area. That is, muscles with larger average fiber areas and a higher proportion of fiber area tend to be denser. Importantly, using the age and region dependent measurements of muscle density that we provide may increase the accuracy of PCSA estimations. Although we found statistically significant differences related to ontogeny and anatomical region, if density cannot be measured directly, the specific values presented herein should be used to improve accuracy. If a single muscle density constant that has been better validated than the ones presented in the previous literature is preferred, then 1.0558 and 1.0502 g/cm3 would be reasonable constants to use across all adult and juvenile muscles respectively.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Leonard, Kaitlyn C. and Worden, Nikole and Boettcher, Marissa L. and Dickinson, Edwin and Omstead, Kailey M. and Burrows, Anne M. and Hartstone-Rose, Adam}, year={2021}, month={Jan} }
 @article{leonard_worden_boettcher_dickinson_hartstone-rose_2021, title={Effects of freezing and short-term fixation on muscle mass, volume, and density}, volume={5}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.24639}, DOI={10.1002/ar.24639}, abstractNote={Preventing postmortem deterioration of soft-tissues is an important requisite of anatomical research. In order to provide corrections for potential myological distortions, this study quantifies the acute effects of freezing, formalin fixation and ethanol storage using muscles from (n = 46) rabbits (Oryctolagus cuniculus). Bilateral dissections of specific muscles were performed and each side was assigned to a different preparation group (fresh, formalin fixation only, fixation followed by short duration ethanol storage, and freezing once or twice). We demonstrate that short-term freezing at -20C and thawing have no significant effect on muscle mass, volume, and density while short-term formalin fixation and ethanol storage significantly reduces mass and volume (density remains relatively constant.) Although freezing may have less of an effect on the gross morphometric characteristics of the musculature than ethanol storage, slow freezing damages muscle microanatomy, and therefore, faster freezing and other modes of preservation such as formalin fixation and ethanol storage may be preferable. Based on our results, we derived the following correction factors for each preparation: the mass of specimens stored in 70% ethanol should be multiplied by 1.69 to approximate fresh muscle mass, and specimens fixed in 10% formalin multiplied by 1.32. Although not significant, specimens frozen-once were slightly less massive and could be multiplied by 1.03 (frozen-twice ×1.09). The volumetric corrections are: ethanol 1.64; 10% formalin 1.32; frozen-once 1.03; frozen-twice 1.10. While the density of ethanol preserved specimens is slightly less than that of fresh ones (correction: 1.03), those preserved in formalin and frozen maintain nearly the same density.}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, publisher={Wiley}, author={Leonard, Kaitlyn C. and Worden, Nikole and Boettcher, Marissa L. and Dickinson, Edwin and Hartstone-Rose, Adam}, year={2021}, month={May} }
 @article{dickinson_davis_deutsch_patel_nijhawan_patel_blume_gannon_turcotte_walker_et al._2021, title={Evaluating bony predictors of bite force across the order Carnivora}, volume={8}, ISSN={["1097-4687"]}, DOI={10.1002/jmor.21400}, abstractNote={In carnivorans, bite force is a critical and ecologically informative variable that has been correlated with multiple morphological, behavioral, and environmental attributes. Whereas in vivo measures of biting performance are difficult to obtain in many taxa-and impossible in extinct species-numerous osteological proxies exist for estimating masticatory muscle size and force. These proxies include both volumetric approximations of muscle dimensions and direct measurements of muscular attachment sites. In this study, we compare three cranial osteological techniques for estimating muscle size (including 2D-photographic and 3D-surface data approaches) against dissection-derived muscle weights and physiological cross-sectional area (PCSA) within the jaw adductor musculature of 40 carnivoran taxa spanning eight families, four orders of magnitude in body size, and the full dietary spectrum of the order. Our results indicate that 3D-approaches provide more accurate estimates of muscle size than do surfaces measured from 2D-lateral photographs. However, estimates of a muscle's maximum cross-sectional area are more closely correlated with muscle mass and PCSA than any estimates derived from muscle attachment areas. These findings highlight the importance of accounting for muscle thickness in osteological estimations of the masticatory musculature; as muscles become volumetrically larger, their larger cross-sectional area does not appear to be associated with a proportional increase in the attachment site area. Though volumetric approaches approximate muscle dimensions well across the order as a whole, caution should be exercised when applying any single method as a predictor across diverse phylogenies.}, journal={JOURNAL OF MORPHOLOGY}, author={Dickinson, Edwin and Davis, Jillian S. and Deutsch, Ashley R. and Patel, Dhuru and Nijhawan, Akash and Patel, Meet and Blume, Abby and Gannon, Jordan L. and Turcotte, Cassandra M. and Walker, Christopher S. and et al.}, year={2021}, month={Aug} }
 @article{dickinson_pastor_santana_hartstone-rose_2021, title={Functional and ecological correlates of the primate jaw abductors}, volume={305}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.24772}, DOI={10.1002/ar.24772}, abstractNote={While the adductor musculature of the primate jaw has been extensively analyzed within the context of dietary and social ecology, little is known about the corresponding muscles of jaw abduction. Nonetheless, these muscles significantly contribute to a species' maximum gape potential, and thus might constrain dietary niche diversity and impact social display behaviors. In this study, we quantify the architectural properties of the digastric (a jaw abductor) and lateral pterygoid (a jaw abductor and anterior translator) across a broad sample of male and female anthropoid primates. We test the hypothesis that the abductor musculature reflects specialization to dietary and behavioral ecology. Our sample comprises 14 catarrhine and 13 platyrrhine species spanning a wide range of dietary and social categories. All specimens were sharp dissected and muscles subsequently chemically digested using a standardized protocol. Our findings demonstrate that relative fascicle lengths within the lateral pterygoid (but not the digastric) are significantly greater within species that habitually consume larger food items. Meanwhile, canine length is more strongly associated with fascicle lengths in the digastric than in the lateral pterygoid, particularly within males. Neither dietary mechanical resistance nor the intensity of social competition relates to the size or architectural properties of the jaw abductors. These findings suggest that dietary-and to a lesser extent, socioecological-aspects of a primate's life history may be reflected in the architecture of these muscles, albeit to varying degrees. This underlines the importance of considering the complete masticatory apparatus when interpreting the evolution of the primate jaw.}, number={5}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, publisher={Wiley}, author={Dickinson, Edwin and Pastor, Francisco and Santana, Sharlene E. and Hartstone-Rose, Adam}, year={2021}, month={Sep} }
 @article{hartstone-rose_dickinson_deutsch_worden_hirschkorn_2021, title={Masticatory muscle architectural correlates of dietary diversity in Canidae, Ursidae, and across the order Carnivora}, volume={9}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.24748}, DOI={10.1002/ar.24748}, abstractNote={Carnivorans represent extreme ecomorphological diversity, encompassing remarkable variation in form, habitat, and diet. The relationship between the masticatory musculature and dietary ecology has been explored in a number of carnivoran lineages, including felids and the superfamily Musteloidea. In this study, we present novel architectural data on two additional carnivoran families-Ursidae and Canidae-and supplement these previous studies with additional felid, musteloid, herpestid, hyaenid, and viverrid taxa (a total of 53 species across 10 families). Gross dissection data were collected following a standardized protocol-sharp dissection followed by chemical digestion. Summed jaw adductor forces were also transformed into bite force estimates (BF) using osteologically calculated leverages. All data were linearized, log-transformed, and size-adjusted using two proxies for each taxon-body mass (BM) and cranial geometric mean-to assess relative scaling trends. These architectural data were then analyzed in the context of dietary ecology to examine the impact of dietary size (DS) and dietary mechanical properties (DMP). Muscle mass, physiological cross-sectional area, and BF scaled with isometry or positive allometry in all cases, whereas fascicle lengths (FLs) scaled with isometry or negative allometry. With respect to diet, BM-adjusted FLs were strongly correlated with DS in musteloids, but not in any other lineage. The relationship between size-adjusted BF and DMP was also significant within musteloids, and across the sample as a whole, but not within other individual lineages. This interfamilial trend may reflect the increased morphological and dietary diversity of musteloids relative to other carnivoran groups.}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, publisher={Wiley}, author={Hartstone-Rose, Adam and Dickinson, Edwin and Deutsch, Ashley R. and Worden, Nikole and Hirschkorn, Gabrielle A.}, year={2021}, month={Sep} }
 @article{dickinson_boettcher_smith_worden_swindell_seelye_pastor_hartstone-rose_2021, title={Myological variation in the forearm anatomy of Callitrichidae and Lemuridae}, volume={5}, ISSN={["1469-7580"]}, url={https://doi.org/10.1111/joa.13440}, DOI={10.1111/joa.13440}, abstractNote={Abstract The anatomy of the primate forearm is frequently investigated in terms of locomotor mode, substrate use, and manual dexterity. Such studies typically rely upon broad, interspecific samples for which one or two representative taxa are used to characterize the anatomy of their genus or family. To interpret variation between distantly related taxa, however, it is necessary to contextualize these differences by quantifying variation at lower hierarchical levels, that is, more fine‐grained representation within specific genera or families. In this study, we present a focused evaluation of the variation in muscle organization, integration, and architecture within two speciose primate families: the Callitrichidae and Lemuridae. We demonstrate that, within each lineage, several muscle functional groups exhibit substantial variation in muscle organization. Most notably, the digital extensors appear highly variable (particularly among callitrichids), with many unique configurations represented. In terms of architectural variables, both families are more conservative, with the exception of the genus Callimico —for which an increase is observed in forearm muscle mass and strength. We suggest this reflects the increased use of vertical climbing and trunk‐to‐trunk leaping within this genus relative to the more typically fine‐branch substrate use of the other callitrichids. Overall, these data emphasize the underappreciated variation in forearm myology and suggest that overly generalized typification of a taxon's anatomy may conceal significant intraspecific and intrageneric variation therein. Thus, considerations of adaptation within the forearm musculature should endeavor to consider the full range of anatomical variation when making comparisons between multiple taxa within an evolutionary context.}, journal={JOURNAL OF ANATOMY}, publisher={Wiley}, author={Dickinson, Edwin and Boettcher, Marissa L. and Smith, Madison R. and Worden, Nikole A. and Swindell, Sidney R. and Seelye, Jason S. and Pastor, Francisco and Hartstone-Rose, Adam}, year={2021}, month={May} }
 @article{baskin_dickinson_dubois_galiano_hartstone-rose_2020, title={?Amphictis (Carnivora, Ailuridae) from the Belgrade Formation of North Carolina, USA}, volume={8}, ISSN={["2167-8359"]}, DOI={10.7717/peerj.9284}, abstractNote={Miocene terrestrial mammals are poorly known from the Atlantic Coastal Plain. Fossils of the Order Carnivora from this time and region are especially rare. We describe a carnivoran mandible with a p4 from the late Oligocene or early early Miocene Belgrade Formation in Jones County, North Carolina. Comparisons are made with carnivoran jaws with similar premolar and molar lengths from the late Oligocene and Miocene of North America and Eurasia. These indicate that the North Carolina jaw is assignable to the Ailuridae, a family whose only living member is the red panda. The jaw is tentatively referred to Amphictis, a genus known elsewhere from the late Oligocene and early Miocene of Europe and the early Miocene (Hemingfordian) of North America. The North Carolina mandible compares best with the late Oligocene (MP 28) Amphictis ambiguus from Pech du Fraysse, France, the oldest known member of the Family Ailuridae, and with the early Miocene (MN 1-MN 2a) A. schlosseri from southwestern Germany. This identification is compatible with a late late Arikareean (Ar4, early Miocene, MN 2-3 equivalent) age assignment for the other terrestrial mammals of the Belgrade Formation.}, journal={PEERJ}, author={Baskin, Jon and Dickinson, Edwin and DuBois, John and Galiano, Henry and Hartstone-Rose, Adam}, year={2020}, month={Jul} }
 @article{leonard_worden_dickinson_hartstone-rose_2020, title={Anatomical and Ontogenetic Influences on Muscle Density}, volume={34}, ISSN={["1530-6860"]}, DOI={10.1096/fasebj.2020.34.s1.06384}, journal={FASEB JOURNAL}, author={Leonard, Kaitlyn and Worden, Nikole and Dickinson, Edwin and Hartstone-Rose, Adam}, year={2020}, month={Apr} }
 @article{boettcher_dickinson_leonard_herrel_hartstone-rose_2020, title={Anatomical reorganization within the hand and forelimb of <it>Perodicticus potto</it>}, volume={34}, ISSN={["1530-6860"]}, DOI={10.1096/fasebj.2020.34.s1.06629}, abstractNote={Historical behavioral accounts note extraordinarily high grip strength in Perodicticus potto . Anatomical analysis of the potto’s hand and forelimb reveal several specializations that may facilitate this enhanced gripping ability, including a specialized vascular bundle (the retia mirabilia) within the wrist, a hyper‐abducted pollex, and a highly reduced second digit. The myological correlates of grip strength (i.e., the contractile potential of the hand and wrist musculature) of P. potto , however, have yet to be quantitatively evaluated. The current study contrasts the myology of the hand and forearm muscles within P. potto to a series of closely‐related strepsirrhines ( Nycticebus coucang, Otolemur crassicaudatus, Hapalemur griseus, and Eulemur mongoz) , as well as comparing the forearm musculature to a broader (n= 41) primate sample. Despite reports of the potto’s high grip strength, our findings demonstrate relatively below‐average force capacity (relatively low physiological cross‐sectional area) within the digital flexors of this species, which suggests that the gripping ability of this species may be less extraordinary than previously hypothesized. In addition to this observation, we report a number of unusual myological features within the potto, including the largest brachioradialis (an elbow flexor) of any taxon within our sample. Even more surprisingly, we identified an independent extensor indicis within P. potto , despite the vestigial nature of the second digit, and the absence of this muscle within ~25% of other taxa within our sample ‐ all of which possessed a more substantial second digit than the potto. These data underscore the curious nature of the potto’s antebrachial musculature, but suggest that adaptations within the potto’s forelimb may be more related to maximizing endurance grip potential than towards increasing myological force. Support or Funding Information National Science Foundation (IOS‐15‐57125 and BCS‐14‐40599)}, journal={FASEB JOURNAL}, author={Boettcher, Marissa and Dickinson, Edwin and Leonard, Kaitlyn and Herrel, Anthony and Hartstone-Rose, Adam}, year={2020}, month={Apr} }
 @article{hartstone-rose_boettcher_seelye_worden_dickinson_2020, title={Intraspecific and intrafamilial variation in primate forearm muscle architecture}, volume={34}, ISSN={["1530-6860"]}, DOI={10.1096/fasebj.2020.34.s1.05802}, abstractNote={Recent studies have examined locomotion and postural correlates of primate forearm muscle architecture. However, these have done so using relatively small sample sizes – usually one or two specimens per species, and relatively few species per genus and family. Thus, little is known about intraspecific variation in forearm muscle fiber architecture in primates, and whether there are notable differences in these variables between closely related taxa. The current study addresses these deficits by assessing both qualitative (presence/absence of specific muscles) and quantitative (physiological cross-sectional area [PCSA], fascicle length [FL] and muscle mass [MM]) differences in forearm muscle architecture of larger intraspecific and samples with greater coverage of specific primate families than had been included in previous work. Namely, we studied 30 callitrichid specimens from 11 species, 15 lemurid specimens from 7 species and 9 cebids from two species - a total sample size of 54 specimens from 20 species. Within species, FL varied the greatest among architectural variables and MM varied the least. We also found that there is great variation in both the extent of separation and fusion of flexor digitorum superficialis and profundus, and in the extent of accessory extensors in most species of callitrichids and Saimiri, but no variation in the gross forearm muscle architecture within lemurids. More than a quarter of the callitrichid specimens had forearm muscle configurations that deviate from their standard published description, suggesting that blanket characterizations of anatomical configurations at the genus or family level may obscure potentially important intra- and inter-specific trends. Support or Funding Information National Science Foundation: IOS-15-57125, BCS-14-40599}, journal={FASEB JOURNAL}, author={Hartstone-Rose, Adam and Boettcher, Marissa and Seelye, Jason and Worden, Nikole and Dickinson, Edwin}, year={2020}, month={Apr} }
 @article{flores_eldridge_elminowski_dickinson_hartstone-rose_2020, title={The Howl of Rancho La Brea: the Functional morphology of Pleistocene canid hyoids}, volume={34}, ISSN={["1530-6860"]}, DOI={10.1096/fasebj.2020.34.s1.01798}, abstractNote={The Rancho La Brea (RLB) fossils housed at the La Brea Tar Pits and Museum in Los Angeles, California represent one of the richest collections of carnivoran fossils in the world. The collection is particularly well known for exceptional preservation, including that of of rare and understudied bones. Among these, the RLB collection houses hyoids from several extinct species, including relatively large samples of specimens from the dire wolf (Canis dirus) and the coyote (Canis latrans). In this study, we compare fossilized hyoid elements from these two fossil samples to modern specimens: the gray wolf (C. lupus), red wolf (C. rufus), and modern coyote (C. latrans). Seven measurements were taken on each long bone of the hyoid apparatus and eight measurements of the u-shaped basihyoid. Principal component analysis was performed to determine statistical differences between species and the drivers of those morphological differences. For most of the bones, the majority of the variation was driven by size. Red wolves, modern coyotes, and RLB coyotes could not be differentiated from each other based on any of the hyoid elements, but dire wolves could be clearly differentiated from all other canids for all elements. The hyoid apparatus of C. dirus is larger and more robust than that of C. lupus, its closest modern analogue. As larger hyoids have been associated with a lower vocal frequency, this distinction would likely result in the vocalizations of C. dirus occurring at a lower frequency than those produced by C. lupus. Support or Funding Information North Carolina State University Office of Undergraduate Research Grant}, journal={FASEB JOURNAL}, author={Flores, Mary and Eldridge, Emma and Elminowski, Erin and Dickinson, Edwin and Hartstone-Rose, Adam}, year={2020}, month={Apr} }
 @article{dickinson_atkinson_meza_kolli_deutsch_burrows_hartstone-rose_2020, title={Visualization and quantification of mimetic musculature via DiceCT}, volume={8}, ISSN={["2167-8359"]}, DOI={10.7717/peerj.9343}, abstractNote={The muscles of facial expression are of significant interest to studies of communicative behaviors. However, due to their small size and high integration with other facial tissues, the current literature is largely restricted to descriptions of the presence or absence of specific muscles. Using diffusible iodine-based contrast-enhanced computed tomography (DiceCT) to stain and digitally image the mimetic mask of Eulemur flavifrons (the blue-eyed black lemur), we demonstrate-for the first time-the ability to visualize these muscles in three-dimensional space and to measure their relative volumes. Comparing these data to earlier accounts of mimetic organization with the face of lemuroidea, we demonstrate several novel configurations within this taxon, particularly in the superior auriculolabialis and the posterior auricularis. We conclude that DiceCT facilitates the study these muscles in closer detail than has been previously possible, and offers significant potential for future studies of this anatomy.}, journal={PEERJ}, author={Dickinson, Edwin and Atkinson, Emily and Meza, Antonio and Kolli, Shruti and Deutsch, Ashley R. and Burrows, Anne M. and Hartstone-Rose, Adam}, year={2020}, month={Jun} }
 @article{boettcher_leonard_dickinson_herrel_hartstone-rose_2019, title={Extraordinary grip strength and specialized myology in the hyper-derived hand of Perodicticus potto?}, volume={235}, ISSN={["1469-7580"]}, url={https://doi.org/10.1111/joa.13051}, DOI={10.1111/joa.13051}, abstractNote={Previous behavioral reports of the African lorisid, Perodicticus potto, have speculated that these animals have an extraordinary grip strength. This ability is hypothesized to be facilitated by a range of anatomical features within the forelimb, ranging from the presence of a retia mirabilia in its wrist to the hyper-abduction of its pollex. Despite numerous behavioral reports, however, this claim of extraordinary grip strength has not been empirically substantiated. This study quantifies the physiological cross-sectional area of the digital flexor muscles within P. potto. These data are compared with a broad primate sample, including several similarly sized strepsirrhines. Contrary to expectation, we found that P. potto actually has relatively below-average digital flexor PCSA. However, we identified other myological characteristics in the upper limb of P. potto that were unexpected, including the largest brachioradialis muscle (an elbow flexor) among our primate sample, and - despite P. potto having only a vestigial second digit - an independent digital extensor indicis that is absent in almost a quarter of our primate sample.}, number={5}, journal={JOURNAL OF ANATOMY}, publisher={Wiley}, author={Boettcher, Marissa L. and Leonard, Kaitlyn C. and Dickinson, Edwin and Herrel, Anthony and Hartstone-Rose, Adam}, year={2019}, month={Nov}, pages={931–939} }
 @article{dickinson_basham_rana_hartstone-rose_2019, title={Visualization and Quantification of Digitally Dissected Muscle Fascicles in the Masticatory Muscles of Callithrix jacchus Using Nondestructive DiceCT}, volume={302}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.24212}, DOI={10.1002/ar.24212}, abstractNote={ABSTRACT The organization and length of a muscle's fascicles imparts its contractile properties. Longer fascicles permit increased muscle excursion, whereas changes in fascicle orientation relate to the overall vector of contractile force. Collecting data on fascicle architecture has traditionally involved destructive and irreversible gross dissection. In recent years, however, new imaging modalities have permitted muscles and their fascicles to be visualized nondestructively. Here, we present data from a primate ( Callithrix jacchus ), in which, for the first time, individual muscle fascicles are digitally “dissected” (segmented and reconstructed) using nondestructive, high‐resolution diffusible iodine‐based contrast‐enhanced computed tomography (DiceCT) techniques. We also present quantitative data on the length and orientation of these fascicles within 10 muscle divisions of the jaw adductor and abductor musculature (superficial, deep, and zygomatic portions of temporalis and masseter; medial and lateral pterygoid; anterior and posterior digastric) and compare these digitally measured lengths to fascicular lengths measured using traditional gross and chemical dissection. Digitally derived fascicle lengths correspond well to their dissection‐derived counterparts. Moreover, our analyses of changes in fascicle orientation across the adductor complex enable us to visualize previously uncharacterized levels of detail and highlight significant variation between adjacent muscle layers within muscle groups (e.g., between superficial, deep, and zygomatic portions of masseter and temporalis). We conclude that this technique offers great potential to future research, particularly for questions centered around the visualization and quantification of obscured and often‐overlooked muscles such as the pterygoid and digastric muscles, and for deriving more accurate models of the masticatory system as a whole. Anat Rec, 302:1891–1900, 2019. © 2019 American Association for Anatomy}, number={11}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, publisher={Wiley}, author={Dickinson, Edwin and Basham, Colin and Rana, Avadh and Hartstone-Rose, Adam}, year={2019}, month={Nov}, pages={1891–1900} }