Papers by Heather F. Smith
PeerJ, 2020
Background: The African wild dog (Lycaon pictus), an endangered canid native to southern and east... more Background: The African wild dog (Lycaon pictus), an endangered canid native to southern and eastern Africa, is distinct among canids in being described as entirely tetradactyl and in its nomadic lifestyle and use of exhaustive predation to capture its prey instead of speed, strength, or stealth. These behavioral and morphological traits suggest a potentially unique set of adaptations. Methods: Here, we dissected the forelimbs of an adult male L. pictus specimen and performed detailed descriptions and quantitative analyses of the musculoskeletal anatomy. Results: Statistical comparisons of muscle masses and volumes revealed that L. pictus has relatively smaller wrist rotators (mm. pronator teres, pronator quadratus, supinator) than any other included carnivoran taxon, suggesting adaptive pressures for antebrachial stability over rotatory movement in the carpus of L. pictus. While a complete digit I is absent in L. pictus, a vestigial first metacarpal was discovered, resulting in changes to insertions of mm. extensor digiti I et II, abductor (et opponens) digiti I and flexor digiti I brevis. Mm. anconeus, brachialis and flexor carpi ulnaris caput ulnare all have more extensive origins in L. pictus than other canids suggesting an emphasis on posture and elbow stability. M. triceps brachii caput laterale has a larger origin in L. pictus and m. triceps brachii caput longum has an additional accessory head. Electromyographic studies have shown this muscle is active during the stance phase of trotting and galloping and is important for storing elastic energy during locomotion. We interpret these differences in size and attachments of muscles in L. pictus as adaptations for long distance running in this highly cursorial species, likely important for exhaustive predation. Absence of a full digit I in L. pictus may increase speed and stride length; however, the retention of a vestigial digit permits the attachment of reduced pollical muscles which may provide additional stability and proprioception to the carpus.
Journal of Mammalian Evolution, 2021
The kinkajou (Potos flavus) is a South and Central American procyonid that can plantarflex and in... more The kinkajou (Potos flavus) is a South and Central American procyonid that can plantarflex and invert its hindfoot around multiple joints in order to fully reverse the hindfoot 180°. However, the myological and osteological adaptions that facilitate this behavior have not been quantified metrically. Osteological correlates of hindfoot reversal have been described in the past, but recent advances in data collection allow for a more comprehensive evaluation of shape differences. Osteological features of the astragalus (talus), calcaneus, and distal tibia of P. flavus were collected and compared to other carnivoran species, including species that are full, partial, and non-reversers of the hindfoot. Hindfoot reversing procyonids were found to possess a relatively smaller medial malleousl, a wider sustentaculum tali, narrower calcaneal tuberosity, and a relatively longer astragalus. In general, the dimensions of the astragalus tend to discriminate hindfoot reversing taxa from other locomotor categories more reliably than the dimensions of the calcaneus or distal tibia. A detailed dissection, description, and documentation of the hind limb muscles in P. flavus was undertaken, and we present the first comprehensive review of its muscular anatomy utilizing muscle maps of the pelvis, femur, tibia, and fibula. Potos flavus has well-developed plantarflexor and invertor muscles, traits which have been hypothesized to characterize species that perform hindfoot reversal. This finding contrasts with other procyonid hindfoot reversing species, such as Bassariscus astutus, which appear to lack muscular adaptations to hindfoot reversal. Muscle semimembranosus, a muscle that facilitates hind limb suspension, was also enlarged. Overall, the hind limb musculature and hindfoot osteology of the kinkajou are consistent with proposed adaptations to hindfoot reversal.
Diagnostics, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The Anatomical Record, 2022
The Anatomical Record, 2022
We present new fossil records of the geoemydid turtle Bridgeremys pusilla from the Uinta Formatio... more We present new fossil records of the geoemydid turtle Bridgeremys pusilla from the Uinta Formation of Utah. Turtles are abundant throughout the unit, and known taxa are similar to those from the older strata in the Upper Green River Basin in Wyoming from the Bridger and Washakie Formations. B. pusilla is known from Bridgerian deposits but was not previously known from after the Turtle Bluff Member of the Bridger Formation. The taxon was coveal with two species of the geoemydid Echmatemys (E. callopyge and E. wyomingensis), a common genus of
Journal of Pediatric Surgery Case Reports, 2022
Background: Pediatric rectal injuries are rare and occur mainly due to motor vehicle accidents, f... more Background: Pediatric rectal injuries are rare and occur mainly due to motor vehicle accidents, firearms, sexual abuse, and other varying causes of penetrating trauma. Common management of cases generally includes primary suture repair with or without diversion. Recent literature suggests that primary repair without fecal diversion may be performed safely in select children excluding presentation of shock, requirement of multiple blood transfusions, multiple other injuries, or extensive contamination; however, there is limited evidence to consider it yet a first-line strategy. Case presentation: A previously healthy 10-year-old boy was brought to the hospital emergency department following a traumatic rectal injury after falling on a rebar post. Flexible sigmoidoscopy with laparoscopic visualization demonstrated a 1-2 cm full-thickness laceration in the rectal mucosa 10 cm proximal to the anal margin. The laceration was successfully repaired with endoscopic clipping. Subsequently, the patient was discharged and had no additional complications during outpatient follow-up. Conclusions: This case demonstrates the successful use of endoscopic clipping as a treatment modality in the management of a grade IV pediatric rectal injury. While additional research is necessary, endoscopic clipping may serve as an additional treatment option when handling restrictive pediatric anatomy or as an alternative to primary suture closure with or without fecal diversion.
Scientific Reports
Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of ... more Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas. Herein, we describe a new side-necked turtle (Pleurodira), Pleurochayah appalachius gen. et sp. nov., which is a basal member of the Bothremydidae. Pleurochayah appalachius gen. et sp. nov. shares synapomorphic characters with other bothremydids, including shared traits with Kurmademydini and Cearachelyini, but has a unique combination of skull and shell traits. The new taxon is significant because it is the oldest crown pleurodiran turtle from North America and Laurasia, predating bothremynines Algorachelus peregrinus and Paiutemys tibert from Europe and North America respectively. This discovery also documents the oldest evidence of dispersal of crown Pleurodira from Gondwana to Laurasia. Pleurochayah appalachius gen. et sp. nov. is compared to previously described fossil pleurodires, placed in a modified phylogenetic analysis of pelo...
Integrative and Comparative Biology
The snow leopard (Panthera uncia) is anatomically and physiologically adapted for life in the roc... more The snow leopard (Panthera uncia) is anatomically and physiologically adapted for life in the rocky terrain of alpine zones in Central and South Asia. Panthera uncia is scansorial, and typically hunts solitarily by using overhead ambush of prey, rather than the typical stalking pattern of other large pantherines. In this study, we conducted dissections, detailed documentation, and illustrated the forelimb anatomy of two adult P. uncia specimens (1M/1F). Qualitative and quantitative data revealed an intriguing combination of functional adaptations illustrating a balance between the diverse demands of head-first descent, pouncing, climbing across rocky terrain, restraint of large prey, rapid pursuit, and navigating deep snow. In many forelimb proportions, P. uncia is intermediate between the cursorial Acinonyx jubatus (cheetah) and the scansorial forest dwelling Panthera onca (jaguar). Enlarged scapular and pectoral musculature provide stability to the shoulder girdle during grappling...
Diagostics, 2020
The retroesophageal aberrant right subclavian artery (ARSA) is a variation of the aortic arch tha... more The retroesophageal aberrant right subclavian artery (ARSA) is a variation of the aortic arch that occurs asymptomatically in most patients. However, when symptomatic, it is most commonly associated with dysphagia. ARSA has also been noted as a location of potentially severe aneurysms in some patients, as well as posing a risk during surgical interventions in the esophageal region. This case study analyzes two individuals with ARSA morphology in comparison to a normal sample in order to gain a better anatomical understanding of this anomaly, potentially leading to better risk assessment of ARSA patients going forward. The diameter of the ARSA vessel was found to be substantially larger than both the right subclavian artery and brachiocephalic trunk of the subjects with classic aortic arch anatomy. As many ARSA individuals are asymptomatic, we hypothesize that the relative size of the ARSA may dictate its contribution to the presence and/or severity of associated symptomatology.
PaleoBios, 2020
Numerous geoemydid turtle fossils from the extinct genus Echmatemys have been recovered from the ... more Numerous geoemydid turtle fossils from the extinct genus Echmatemys have been recovered from the middle Eocene Uinta Formation, Uinta Basin, Utah over the past several decades. Here, we tested whether co-occurring Uintan species Echmatemys callopyge and E. uintensis can be reliably differentiated based on epiplastral morphology, and whether their geospatial distributions overlapped significantly. The geographic spatial and stratigraphic distributions of Uinta Basin E. callopyge and E. uintensis specimens were compared using ArcGIS and analysis of variance (ANOVA). The analysis revealed overlapping geographic distributions of these two species, and no significant differences in stratigraphic dispersal. This finding of extensive geospatial overlap between the two Uintan Echmatemys species highlights the need for accurate taxonomic identification, such as the gular scale morphology validated here. In addition, we sought to address a methodological question regarding the relative efficacy of data complexity in this context. Using epiplastra from three additional Eocene species of Echmatemys, we employed hierarchical analyses of increasing data complexity, from standard linear dimensions to 2D geometric morphometrics to 3D laser scans, to determine the degree to which data complexity contributes to taxonomic assessments within this genus. Uintan species E. callopyge and E. uintensis were found to differ significantly in epiplastral shape as captured by all three categories of data. These findings verify that these two co-occurring species can be differentiated consistently using the shape of the gular scale, and that the use of geometric morphometrics can improve identification of fragmentary specimens. Among the non-Uintan species, dorsal and ventral 2D landmark data reliably differentiated among species, but the linear dimensions were less useful.
Diagnostics, 2020
Median arcuate ligament syndrome (MALS) is a rarely diagnosed condition resulting from compressio... more Median arcuate ligament syndrome (MALS) is a rarely diagnosed condition resulting from compression of the celiac trunk (CT) by the median arcuate ligament (MAL) of the diaphragm. Ischemia due to reduced blood flow through the CT and/or neuropathic pain resulting from celiac ganglion compression may result in a range of gastrointestinal symptoms, including nausea, postprandial discomfort, and weight loss. However, the mechanism of compression and its anatomical correlates have been incompletely delineated. It has been hypothesized that CT angle of origination may be more acute in individuals with MALS. Here, frequency of anatomical variation in the MAL and CT were assessed in 35 cadaveric subjects (17M/18F), including the vertebral level of origin of CT and superior mesenteric artery (SMA), the distance between CT and MAL and SMA, the angles of origination of CT and SMA, the diameter at the CT base, and MAL/CT overlap. Females exhibited significantly higher rates of inferred MAL/CT overlap than males. Significant correlations were revealed between MAL/CT overlap and angles of origination of the CT and SMA. Vertebral level of origin of the CT in individuals with MAL/CT overlap was not significantly more superior than in those without. This study also revealed a significant relationship between MAL/CT overlap and angle of origination of the CT, which has clinical implications for understanding the anatomy associated with MALS.
Anatomical Science International, 2020
Circumscapular pain is a frequent complaint in clinical practice. The dorsal scapular and long th... more Circumscapular pain is a frequent complaint in clinical practice. The dorsal scapular and long thoracic nerves course through the neck, where they may become entrapped between or within adjacent scalene muscles. Additionally, a high frequency of brachial plexus “piercing” variants have recently been documented, and it is unclear how they influence branching patterns
distally along the brachial plexus. In the project reported here we strived to identify and quantify variations in dorsal scapular nerve and long thoracic nerve secondary to brachial plexus piercing variation. Ninety brachial plexuses from human cadavers (45 female/45 male) were evaluated to identify nerve branching patterns, specifically piercing versus non-piercing variants in
the brachial plexus roots and nerves. Anatomical entrapment of the dorsal scapular nerve and long thoracic nerve was found in high frequencies (60.8% and 44.6%, respectively). Anomalous brachial plexus piercing variants were associated with higher frequencies of distal nerve branches also coursing through the scalene musculature, and there was a statistically significant
correlation between brachial plexus and long thoracic nerve piercings (p = 0.027). Anatomical entrapment of nerves within scalene musculature is common and may be causative factors for idiopathic circumscapular pain, dorsalgia, and dysfunction of scapulohumeral rhythm. This study revealed a link between anatomical arrangement of the brachial plexus and occurrence
of long thoracic nerve entrapment, which may lead to a series of cascading neurologic effects in which affected individuals may suffer from increased incidence of thoracic outlet syndrome and long thoracic nerve entrapment resulting in additional symptoms of interscapular pain and compromised shoulder mobility.
PeerJ, 2019
Background. Variation within the submandibular triangle, including variant paths of facial neurov... more Background. Variation within the submandibular triangle, including variant paths of facial neurovasculature, could increase risk of neurovascular derangement during submandibular gland (SMG) dysfunction, enlargement, interventions, or removal. Methods. Frequency of anatomical variants enveloped within or piercing the SMG, including facial artery, vein, or branches of CN VII, were assessed in 70 cadaveric submandibular glands (39M/31F). Results. Eighteen of 70 SMGs (25.7%) were pierced by at least one aberrant neu-rovasculature structure: Facial artery most frequently (n = 13), followed by facial vein (n = 2), inferior labial artery and vein (n = 1), and CN VII cervical branch (n = 1). This study demonstrated the high variability of neurovasculature within submandibular parenchyma. These aberrant neurovascular structures, especially facial artery, are in danger of compromise during surgical and other medical procedures on the SMG. To avoid potential neurovascular compromise, ultrasonographic or other imaging is recommended prior to procedures involving the SMG.
Palaeontologia Electronica, 2019
The Arlington Archosaur Site (AAS) is a Cenomanian (93-99 Mya) fossil locality in the Woodbine Fo... more The Arlington Archosaur Site (AAS) is a Cenomanian (93-99 Mya) fossil locality in the Woodbine Formation of Texas. Woodbine deposits form primarily terrigenous near shore and shallow marine depositional systems, including shelf, deltaic, and fluvial environments. The AAS is the oldest Upper Cretaceous unit in the Gulf Coastal Plain, and the most complete fossil ecosystem discovered in southwestern Appalachia. It preserves a freshwater/brackish wetland situated in a low-lying coastal plain. The site contains diverse fossil vertebrate and invertebrate faunas and abundant carbonized plant material. The taphonomy of the site is complex, frequently resulting in fragmentary specimens due to a mixture of environmental transport, biological accumulation, pervasive crocodyliform predation, massive storms, wildfires, and widespread flooding
events. Numerous new reptilian taxa (particularly crocodyliform) have been recently described, but turtles from the site have not been taxonomically identified. This study documents fossil shell material of AAS turtles, most of which were previously unknown
from the site. Results include a new baenid species, “Trinitichelys” maini sp. nov., numerous elements of the helochelydrid Naomichelys, a small trionychid, and a bothremydid. Insights from the turtle faunas at the AAS contribute to our growing understanding of the coastal ecosystems of southwestern Appalachia at the beginning of the Upper Cretaceous.
Scientific Reports, 2019
Avian ceca, a pair of blind sacs arising from the junction of the ileum and colon, are homologous... more Avian ceca, a pair of blind sacs arising from the junction of the ileum and colon, are homologous to the cecum in mammals. Cecal size is hypothesized to depend on dietary proclivities and pressures, with faunivorous species having short ceca, whereas herbivorous species have long ceca. previous tests of this hypothesis, however, did not account for phylogenetic pseudoreplication among closely related taxa. We collated published data on cecal length, dietary category, flying ability, and body mass from 155 avian taxa. Character states were mapped onto a phylogenetic framework, and the permutation tail probability test was used to detect phylogenetic signal in each character. phylogenetic signal is significant among the characters. As with the cecoappendicular complex in mammals, closely-related birds tend to have similar cecal length. to account for phylogenetic pseudoreplication, we performed phylogenetic generalized least squares regression on cecal length and body mass with dietary category, superordinal-level clade, and flying ability as cofactors. The best-fitting regression model supports the dietary hypothesis for the avian cecum. Among sampled birds of comparable body mass, mean cecal length is significantly longer in herbivorous species than in carnivorous ones (p = 0.008), presumably allowing the extraction of nutrients without the burden of fermenting bulky masses of dietary fiber. exceptions to this trend, however, suggest that avian ceca are functionally complex and may have additional roles in water balance and nitrogen recycling. The avian ceca are a pair of blind sacs that arise from the junction of the ileum and colon, and may extend alongside the ileum 1-3. These structures are highly variable among species of birds. For example, the ceca are short in the Columbidae (pigeons and doves), but they can project a large distance along the ileum in the Galloanserae (fowl) 4. However, the causes for this variation remain poorly understood. A homologous structure is found in many mammalian species, the cecum. Smith and colleagues recently proposed the term "cecoappendicular com-plex" to reflect the fact that the mammalian cecum evolves in concert with its attached appendix 5. The cecoap-pendicular complex has been recently shown not to correlate with diet, social behavior, or any other ecological factor across mammals 5,6. Instead, the mammalian cecoappendicular complex exhibits significant phylogenetic signal, such that new phenotypes appear restricted primarily by phylogenetic conservatism across mammals (i.e., the tendency of closely-related species to resemble one another irrespective of the adaptive landscape) 5-7. This intriguing finding raises the question as to whether the homologues in birds, the ceca, share similar evolutionary conservatism. Avian ceca span a wide range of morphological types, from essentially absent to small and lymphoid to large and glandular 1,4. They serve various diverse functions, including fermentation, water absorption, digestion, and immunity, which may be performed to varying degrees in different species and cecal types. In herbivorous birds that feed on fiber-rich plant material, ceca house microorganisms that presumably assist in the breakdown of fiber through fermentation via anaerobic degradation to ammonia and volatile fatty acids 8,9. In order for nutrient absorption to take place in the ceca, particles are refluxed from the rectum into the ceca along with digestive fluid and urine 3,10,11. Retrograde urine transport therefore directs uric acid to the site of fermentation, and uric acid is likely to be a major substrate for fermentation. Most microorganisms found within the avian ceca are able to degrade urea and uric acid into carbon dioxide and ammonia, which can be rapidly absorbed and utilized for the production of amino acids and protein 3,12-14. Maintenance of water balance is another vital function that may be performed by the avian ceca, because sodium and water are reabsorbed there in great abundance 15-17. Many species also possess a cecal tonsil composed of lymphoid tissue, suggesting the ceca play a role in immune
Myology of the Head, Neck, and Thoracic Region of the Lesser Grison (Galictis cuja) in Comparison with the Red Panda (Ailurus fulgens) and Other Carnivorans: Phylogenetic and Functional Implications
Journal of Mammalian Evolution, 2017
Abstract The lesser grison (Galictis cuja) and the red
panda (Ailurus fulgens) represent two oppo... more Abstract The lesser grison (Galictis cuja) and the red
panda (Ailurus fulgens) represent two opposed morphofunctional
musteloid extremes. The mid-sized lesser
grison is primarily terrestrial, a frequent burrow-dweller,
and carnivorous, while the larger, scansorial red panda
eats bamboo. This study documents the axial myology
of these species, including muscle descriptions, weights,
and optimizations. Muscle maps are also provided for the
lesser grison, representing the first axial maps for a wildcaught
carnivoran. The functional analyses revealed that
G. cuja, contrary to A. fulgens, possesses longer, stronger,
and subdivided neck muscles. It also possesses a
thoraco-lumbar iliocostalis system that is more developed
than the longissimus complex, and numerous, robust, and
laterally inserted deep bellies of the cervical and thoracic
transversospinalis systems. These specializations allow
powerful neck movement during hunting and transport
of heavy prey as well as axial flexibility, facilitating
bounding gaits and lateral movements while navigating
subterranean galleries. Some myological traits of the red
panda differ from those expected in a highly herbivorous
taxon (e.g., m. sternocephalicus, m. masseter), and may
reflect its depredatory ancestry. The optimization analysis
revealed phylogenetically informative traits across
Carnivora, including the absence of m. longissimus
capitis in Mephitidae, the absence of spinous thoracic
origins for m. biventer cervicis in Must
eloidea, and the presence of a relatively lateral insertion
of m. rectus dorsalis capitis intermedius in the clade
Ictonychinae+Lutrinae+Mustelinae. This study reveals
key associations between axial myological and
osteological features that will prove useful for future
studies of carnivorans.
The evolutionary pressures leading to the appearance of the cecal appendix, its evolutionary rela... more The evolutionary pressures leading to the appearance of the cecal appendix, its evolutionary relationships with the cecum, and the link between these gastrointestinal characters and ecology remain controversial. We collected data on appendix presence and size,other gastrointestinal characters, ecological variables, dietary habits, and social characters hypothesized to drive appendix evolution for 533 mammalian species. Using phylogeny-informed analyses, we identified the first evidence of a positive correlation between appendix presence and cecal apex thickness, and a correlation with cecal morphology, suggesting that the appendix and cecum may be evolving as a module, the cecoappendicular complex. A correlation between appendix presence and concentration of cecal lymphoid tissue supports the hypothesis of an adaptive immune function for this complex. Other new findings include an inverse correlation between relative cecum length and habitat breadth,and positive relationships between cecum length and mean group size, and between colon length and weaning age.
Neurogenic thoracic outlet syndrome (NTOS) is the most common type of TOS. Typically it results f... more Neurogenic thoracic outlet syndrome (NTOS) is the most common type of TOS. Typically it results from impingement of the neurovasculature as it passes between the anterior and middle scalene muscles; this classic anatomical relationship being the foundation of clinical diagnosis. Positional testing relies on vascular compromise occurring when the subclavian artery is compressed in this space. This study describes several anatomical variations observed in this relationship. Sixty-five cadavers (35m/30f) were assessed to determine the frequency and extent of brachial plexus branching variants. A total of thirty-one variations from " classic " anatomy were observed (47.7%). In two specimens (3.1%), the entire superior trunk coursed completely anterior to the anterior scalene in a position of relative vulnerability. In 27 instances, a portion of or the entire superior trunk pierced the anterior scalene muscle, and in two, the middle trunk also pierced the muscle belly. Interestingly, while two bilateral branching variations were observed, the majority occurred unilaterally, and almost exclusively on the left side. There were no sex differences in frequency. The high frequency of these variations and their potential to predispose patients to neurogenic TOS suggest that current diagnostic methods may be insufficient in clinical diagnosis. Due to lack of vascu-lar compromise, patients with the piercing variant would not display positive signs on the traditional positional tests. The use of ultrasound to determine the route of the brachial plexus could determine whether this variation is present in patients who suffer from TOS symptoms but lack a diagnosis based on traditional positional testing.
Human Biology, 2014
Molecular-based characterizations of Andean peoples are traditionally conducted in the service of... more Molecular-based characterizations of Andean peoples are traditionally conducted in the service of elucidating continent-level evolutionary processes in South America. Consequently, genetic variation among "western" Andean populations is often represented in relation to variation among "eastern" Amazon and Orinoco River Basin populations. This west-east contrast in patterns of population genetic variation is typically attributed to large-scale phenomena, such as dual founder colonization events or differing long-term microevolutionary histories. However, alternative explanations that consider the nature and causes of population genetic diversity within the Andean region remain underexplored. Here we examine population genetic diversity in the Peruvian Central Andes using data from the mtDNA first hypervariable region and Y-chromosome short tandem repeats among 17 newly sampled populations and 15 published samples. Using this geographically comprehensive data set, we first reassessed the currently accepted pattern of western versus eastern population genetic structure, which our results ultimately reject: mtDNA population diversities were lower, rather than higher, within Andean versus eastern populations, and only highland Y-chromosomes exhibited significantly higher within-population diversities compared with eastern groups. Multiple populations, including several highland samples, exhibited low genetic diversities for both genetic systems. Second, we explored whether the implementation of Inca state and Spanish colonial policies starting at about ad 1400 could have substantially restructured population genetic variation and consequently constitute a primary explanation for the extant pattern of population diversity in the Peruvian Central Andes. Our results suggest that Peruvian Central Andean population structure cannot be parsimoniously explained as the sole outcome of combined Inca and Spanish policies on the region's population demography: highland populations differed from coastal and lowland populations in mtDNA genetic structure only; highland groups also showed strong evidence of female-biased gene flow and/or effective sizes relative to other Peruvian ecozones. Taken together, these findings indicate that population genetic structure in the Peruvian Central Andes is considerably more complex than previously reported and that characterizations of and explanations for genetic variation may be best pursued within more localized regions and defined time periods.
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Papers by Heather F. Smith
distally along the brachial plexus. In the project reported here we strived to identify and quantify variations in dorsal scapular nerve and long thoracic nerve secondary to brachial plexus piercing variation. Ninety brachial plexuses from human cadavers (45 female/45 male) were evaluated to identify nerve branching patterns, specifically piercing versus non-piercing variants in
the brachial plexus roots and nerves. Anatomical entrapment of the dorsal scapular nerve and long thoracic nerve was found in high frequencies (60.8% and 44.6%, respectively). Anomalous brachial plexus piercing variants were associated with higher frequencies of distal nerve branches also coursing through the scalene musculature, and there was a statistically significant
correlation between brachial plexus and long thoracic nerve piercings (p = 0.027). Anatomical entrapment of nerves within scalene musculature is common and may be causative factors for idiopathic circumscapular pain, dorsalgia, and dysfunction of scapulohumeral rhythm. This study revealed a link between anatomical arrangement of the brachial plexus and occurrence
of long thoracic nerve entrapment, which may lead to a series of cascading neurologic effects in which affected individuals may suffer from increased incidence of thoracic outlet syndrome and long thoracic nerve entrapment resulting in additional symptoms of interscapular pain and compromised shoulder mobility.
events. Numerous new reptilian taxa (particularly crocodyliform) have been recently described, but turtles from the site have not been taxonomically identified. This study documents fossil shell material of AAS turtles, most of which were previously unknown
from the site. Results include a new baenid species, “Trinitichelys” maini sp. nov., numerous elements of the helochelydrid Naomichelys, a small trionychid, and a bothremydid. Insights from the turtle faunas at the AAS contribute to our growing understanding of the coastal ecosystems of southwestern Appalachia at the beginning of the Upper Cretaceous.
panda (Ailurus fulgens) represent two opposed morphofunctional
musteloid extremes. The mid-sized lesser
grison is primarily terrestrial, a frequent burrow-dweller,
and carnivorous, while the larger, scansorial red panda
eats bamboo. This study documents the axial myology
of these species, including muscle descriptions, weights,
and optimizations. Muscle maps are also provided for the
lesser grison, representing the first axial maps for a wildcaught
carnivoran. The functional analyses revealed that
G. cuja, contrary to A. fulgens, possesses longer, stronger,
and subdivided neck muscles. It also possesses a
thoraco-lumbar iliocostalis system that is more developed
than the longissimus complex, and numerous, robust, and
laterally inserted deep bellies of the cervical and thoracic
transversospinalis systems. These specializations allow
powerful neck movement during hunting and transport
of heavy prey as well as axial flexibility, facilitating
bounding gaits and lateral movements while navigating
subterranean galleries. Some myological traits of the red
panda differ from those expected in a highly herbivorous
taxon (e.g., m. sternocephalicus, m. masseter), and may
reflect its depredatory ancestry. The optimization analysis
revealed phylogenetically informative traits across
Carnivora, including the absence of m. longissimus
capitis in Mephitidae, the absence of spinous thoracic
origins for m. biventer cervicis in Must
eloidea, and the presence of a relatively lateral insertion
of m. rectus dorsalis capitis intermedius in the clade
Ictonychinae+Lutrinae+Mustelinae. This study reveals
key associations between axial myological and
osteological features that will prove useful for future
studies of carnivorans.