Emma Schachner | Louisiana State University Health Sciences Center in New Orleans (original) (raw)

Papers by Emma Schachner

Research paper thumbnail of Anatomical Variation of the Tarsus in Common Inbred Mouse Strains

Anatomical record (Hoboken, N.J. : 2007), Jan 12, 2016

Rodent models are used for a variety of orthopedic research applications; however, anatomy refere... more Rodent models are used for a variety of orthopedic research applications; however, anatomy references include mostly artistic representations. Advanced imaging techniques, including micro-computed tomography (microCT), can provide more accurate representations of subtle anatomical characteristics. A recent microCT atlas of laboratory mouse (Mus musculus) anatomy depicts the central and tarsal bone III (T3) as a single bone, differing from previous references. Fusion of tarsal bones is generally characterized as pathological secondary to mutations associated with growth factors, and normal variation has not been documented in the mouse tarsus. Therefore, it is unclear if this fusion is a normal or a pathological characteristic. The aim of this study is to characterize the tarsus of the laboratory mouse and compare it to the rat and selected outgroup species (i.e., white-footed mouse) via microCT and histology to determine if the central and T3 are separate or fused into a single bone...

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Research paper thumbnail of The effects of skeletal asymmetry on interpreting biologic variation and taphonomy in the fossil record

Paleobiology, 2018

Biologic asymmetry is present in all bilaterally symmetric organisms as a result of normal develo... more Biologic asymmetry is present in all bilaterally symmetric organisms as a result of normal developmental instability. However, fossilized organisms, which have undergone distortion due to burial, may have additional asymmetry as a result of taphonomic processes. To investigate this issue, we evaluated the magnitude of shape variation resulting from taphonomy on vertebrate bone using a novel application of fluctuating asymmetry. We quantified the amount of total variance attributed to asymmetry in a taphonomically distorted fossil taxon and compared it with that of three extant taxa. The fossil taxon had an average of 27% higher asymmetry than the extant taxa. In spite of the high amount of taphonomic input, the major axes of shape variation were not greatly altered by removal of the asymmetric component of shape variation. This presents the possibility that either underlying biologic trends drive the principal directions of shape change irrespective of asymmetric taphonomic distorti...

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Research paper thumbnail of Introducing the Comparative Atlas of Vertebrate Embryology Online Database

The FASEB Journal, 2015

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Research paper thumbnail of Anatomy of the Respiratory System of the African Grey Parrot ( Psittacus erithacus )

The FASEB Journal, 2018

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Research paper thumbnail of Evaluating the Effects of the Obturator Externus Tendon on the Posterior Femoral Neck

The FASEB Journal, 2018

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Research paper thumbnail of Supplementary Methods from Vertebral morphometrics and lung structure in non-avian dinosaurs

Tables containing the full lists of extant and extinct taxa used in this study, as well as a deta... more Tables containing the full lists of extant and extinct taxa used in this study, as well as a detailed description of the landmark scheme.

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Research paper thumbnail of Supplementary Tables from Vertebral morphometrics and lung structure in non-avian dinosaurs

Additional results tables, showing the results of the Procrustes ANOVAs, as well as the LDA class... more Additional results tables, showing the results of the Procrustes ANOVAs, as well as the LDA classifications of fossil taxa.

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Research paper thumbnail of Preliminary Observations from the First Datasets Available on the CAVE (Comparative Atlas of Vertebrate Embryology) Website

The FASEB Journal, 2015

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Research paper thumbnail of 3D trauma analysis using x-ray microtomography in Tenontosaurus tilletti, Cloverly Formation (Montana, USA)

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Research paper thumbnail of Three-dimensional (3D) lung segmentation for diagnosis of COVID-19 and the communication of disease impact to the public

BMJ Case Reports, 2020

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Research paper thumbnail of Online conferencing software in radiology: Recent trends and utility

Clinical Imaging, 2021

Videoconferencing platforms have recently gained wide attention due to the COVID-19 pandemic, bot... more Videoconferencing platforms have recently gained wide attention due to the COVID-19 pandemic, both within and outside of the medical community. This article reviews various applications of online meeting technology to the radiologic community, not only in response to the recent pandemic but also thereafter. Various platform features are outlined and discussed, specifically with respect to collaboration, training, and patient care. Platforms reviewed are GoToMeeting, Microsoft Teams, Skype, WebEx, and Zoom.

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Research paper thumbnail of Anatomy, ontogeny, and evolution of the archosaurian respiratory system: A case study on Alligator mississippiensis and Struthio camelus

Journal of Anatomy, 2020

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Research paper thumbnail of Respiratory evolution in archosaurs

Philosophical Transactions of the Royal Society B: Biological Sciences, 2020

The Archosauria are a highly successful group of vertebrates, and their evolution is marked by th... more The Archosauria are a highly successful group of vertebrates, and their evolution is marked by the appearance of diverse respiratory and metabolic strategies. This review examines respiratory function in living and fossil archosaurs, focusing on the anatomy and biomechanics of the respiratory system, and their physiological consequences. The first archosaurs shared a heterogeneously partitioned parabronchial lung with unidirectional air flow; from this common ancestral lung morphology, we trace the diverging respiratory designs of bird- and crocodilian-line archosaurs. We review the latest evidence of osteological correlates for lung structure and the presence and distribution of accessory air sacs, with a focus on the evolution of the avian lung-air sac system and the functional separation of gas exchange and ventilation. In addition, we discuss the evolution of ventilation mechanics across archosaurs, citing new biomechanical data from extant taxa and how this informs our reconstr...

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Research paper thumbnail of Osteology of the Late Triassic Bipedal Archosaur Poposaurus gracilis (Archosauria: Pseudosuchia) from Western North America

The Anatomical Record, 2019

Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since th... more Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since the discovery of the holotype fragmentary partial postcranial skeleton in 1915. Poposaurus. gracilis is a member of Poposauroidea, an unusually morphologically divergent clade of pseudosuchians containing taxa that are bipedal, quadrupedal, toothed, edentulous, and some individuals with elongated thoracic neural spines (i.e., sails). In 2003, a well preserved, fully articulated, and nearly complete postcranial skeleton of P. gracilis was discovered with some fragmentary cranial elements from the Upper Triassic Chinle Formation of Grand Staircase‐Escalante National Monument of southern Utah, USA. The aim of this work is to describe the osteology of this specimen in detail and compare P. gracilis to other closely related pseudosuchian archosaurs. The open neurocentral sutures throughout the majority of the vertebral column, the small size of this individual, and the presence of seven evenly spaced cyclic growth marks in the histologically sectioned femur indicate that this specimen was a skeletally immature juvenile, or subadult when it died. The pes of P. gracilis contains multiple skeletal adaptations and osteological correlates for soft tissue structures that support a hypothesis of digitigrady for this taxon. When coupled with the numerous postcranial characters associated with cursoriality, and the many anatomical traits convergent with theropod dinosaurs, this animal likely occupied a similar ecological niche with contemporaneous theropods during the Late Triassic Period. Anat Rec, 303:874–917, 2020. © 2019 American Association for Anatomy

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Research paper thumbnail of Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina ): developmental perspectives on cryptodiran lungs

Journal of Anatomy, 2017

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Research paper thumbnail of Vertebral morphometrics and lung structure in non-avian dinosaurs

Royal Society Open Science, 2018

The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds wh... more The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds whether an avian-style lung is restricted to birds or first appeared in their dinosaurian ancestors, as common osteological correlates for the respiratory system offer limited information on the lungs themselves. Here, we shed light on these issues by using axial morphology as a direct osteological correlate of lung structure, and quantifying vertebral shape using geometric morphometrics in birds, crocodilians and a wide range of dinosaurian taxa. Although fully avian lungs were a rather late innovation, we quantitatively show that non-avian dinosaurs and basal dinosauriforms possessed bird-like costovertebral joints and a furrowed thoracic ceiling. This would have immobilized the lung's dorsal surface, a structural prerequisite for a thinned blood-gas barrier and increased gas exchange potential. This could have permitted high levels of aerobic and metabolic activity in dinosaurs, eve...

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Research paper thumbnail of Cystic Calculus in a Laboratory-housed Green Anole (Anolis carolinensis)

Comparative medicine, 2017

An adult, male, wild-caught, laboratory-housed green anole (Anolis carolinensis) on a locomotor p... more An adult, male, wild-caught, laboratory-housed green anole (Anolis carolinensis) on a locomotor performance study was presented for anorexia. The anole exhibited a 26% weight loss and a thin body condition but was otherwise alert and active. Despite supportive care, the anole's clinical condition deteriorated, necessitating euthanasia. Postmortem examination revealed a 4.5 mm × 2.5-mm cystic calculus, which consisted entirely of sodium urate. Here we describe the clinical findings and locomotor consequences of this disease in a green anole. Although urolithiasis has been reported clinically in reptiles, this report presents the first case of a cystic calculus in a laboratory-housed green anole.

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Research paper thumbnail of Correction: A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America

PloS one, 2015

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Research paper thumbnail of Pedal proportions of Poposaurus gracilis: convergence and divergence in the feet of archosaurs

Anatomical record (Hoboken, N.J. : 2007), 2014

The crocodile-line basal suchian Poposaurus gracilis had body proportions suggesting that it was ... more The crocodile-line basal suchian Poposaurus gracilis had body proportions suggesting that it was an erect, bipedal form like many dinosaurs, prompting questions of whether its pedal proportions, and the shape of its footprint, would likewise "mimic" those of bipedal dinosaurs. We addressed these questions through a comparison of phalangeal, digital, and metatarsal proportions of Poposaurus with those of extinct and extant crocodile-line archosaurs, obligate or facultatively bipedal non-avian dinosaurs, and ground birds of several clades, as well as a comparison of the footprint reconstructed from the foot skeleton of Poposaurus with known early Mesozoic archosaurian ichnotaxa. Bivariate and multivariate analyses of phalangeal and digital dimensions showed numerous instances of convergence in pedal morphology among disparate archosaurian clades. Overall, the foot of Poposaurus is indeed more like that of bipedal dinosaurs than other archosaur groups, but is not exactly like...

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Research paper thumbnail of Origin of the unique ventilatory apparatus of turtles

Nature Communications, 2014

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Research paper thumbnail of Anatomical Variation of the Tarsus in Common Inbred Mouse Strains

Anatomical record (Hoboken, N.J. : 2007), Jan 12, 2016

Rodent models are used for a variety of orthopedic research applications; however, anatomy refere... more Rodent models are used for a variety of orthopedic research applications; however, anatomy references include mostly artistic representations. Advanced imaging techniques, including micro-computed tomography (microCT), can provide more accurate representations of subtle anatomical characteristics. A recent microCT atlas of laboratory mouse (Mus musculus) anatomy depicts the central and tarsal bone III (T3) as a single bone, differing from previous references. Fusion of tarsal bones is generally characterized as pathological secondary to mutations associated with growth factors, and normal variation has not been documented in the mouse tarsus. Therefore, it is unclear if this fusion is a normal or a pathological characteristic. The aim of this study is to characterize the tarsus of the laboratory mouse and compare it to the rat and selected outgroup species (i.e., white-footed mouse) via microCT and histology to determine if the central and T3 are separate or fused into a single bone...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The effects of skeletal asymmetry on interpreting biologic variation and taphonomy in the fossil record

Paleobiology, 2018

Biologic asymmetry is present in all bilaterally symmetric organisms as a result of normal develo... more Biologic asymmetry is present in all bilaterally symmetric organisms as a result of normal developmental instability. However, fossilized organisms, which have undergone distortion due to burial, may have additional asymmetry as a result of taphonomic processes. To investigate this issue, we evaluated the magnitude of shape variation resulting from taphonomy on vertebrate bone using a novel application of fluctuating asymmetry. We quantified the amount of total variance attributed to asymmetry in a taphonomically distorted fossil taxon and compared it with that of three extant taxa. The fossil taxon had an average of 27% higher asymmetry than the extant taxa. In spite of the high amount of taphonomic input, the major axes of shape variation were not greatly altered by removal of the asymmetric component of shape variation. This presents the possibility that either underlying biologic trends drive the principal directions of shape change irrespective of asymmetric taphonomic distorti...

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Research paper thumbnail of Introducing the Comparative Atlas of Vertebrate Embryology Online Database

The FASEB Journal, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Anatomy of the Respiratory System of the African Grey Parrot ( Psittacus erithacus )

The FASEB Journal, 2018

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Research paper thumbnail of Evaluating the Effects of the Obturator Externus Tendon on the Posterior Femoral Neck

The FASEB Journal, 2018

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Research paper thumbnail of Supplementary Methods from Vertebral morphometrics and lung structure in non-avian dinosaurs

Tables containing the full lists of extant and extinct taxa used in this study, as well as a deta... more Tables containing the full lists of extant and extinct taxa used in this study, as well as a detailed description of the landmark scheme.

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Research paper thumbnail of Supplementary Tables from Vertebral morphometrics and lung structure in non-avian dinosaurs

Additional results tables, showing the results of the Procrustes ANOVAs, as well as the LDA class... more Additional results tables, showing the results of the Procrustes ANOVAs, as well as the LDA classifications of fossil taxa.

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Research paper thumbnail of Preliminary Observations from the First Datasets Available on the CAVE (Comparative Atlas of Vertebrate Embryology) Website

The FASEB Journal, 2015

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Research paper thumbnail of 3D trauma analysis using x-ray microtomography in Tenontosaurus tilletti, Cloverly Formation (Montana, USA)

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Three-dimensional (3D) lung segmentation for diagnosis of COVID-19 and the communication of disease impact to the public

BMJ Case Reports, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Online conferencing software in radiology: Recent trends and utility

Clinical Imaging, 2021

Videoconferencing platforms have recently gained wide attention due to the COVID-19 pandemic, bot... more Videoconferencing platforms have recently gained wide attention due to the COVID-19 pandemic, both within and outside of the medical community. This article reviews various applications of online meeting technology to the radiologic community, not only in response to the recent pandemic but also thereafter. Various platform features are outlined and discussed, specifically with respect to collaboration, training, and patient care. Platforms reviewed are GoToMeeting, Microsoft Teams, Skype, WebEx, and Zoom.

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Research paper thumbnail of Anatomy, ontogeny, and evolution of the archosaurian respiratory system: A case study on Alligator mississippiensis and Struthio camelus

Journal of Anatomy, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Respiratory evolution in archosaurs

Philosophical Transactions of the Royal Society B: Biological Sciences, 2020

The Archosauria are a highly successful group of vertebrates, and their evolution is marked by th... more The Archosauria are a highly successful group of vertebrates, and their evolution is marked by the appearance of diverse respiratory and metabolic strategies. This review examines respiratory function in living and fossil archosaurs, focusing on the anatomy and biomechanics of the respiratory system, and their physiological consequences. The first archosaurs shared a heterogeneously partitioned parabronchial lung with unidirectional air flow; from this common ancestral lung morphology, we trace the diverging respiratory designs of bird- and crocodilian-line archosaurs. We review the latest evidence of osteological correlates for lung structure and the presence and distribution of accessory air sacs, with a focus on the evolution of the avian lung-air sac system and the functional separation of gas exchange and ventilation. In addition, we discuss the evolution of ventilation mechanics across archosaurs, citing new biomechanical data from extant taxa and how this informs our reconstr...

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Research paper thumbnail of Osteology of the Late Triassic Bipedal Archosaur Poposaurus gracilis (Archosauria: Pseudosuchia) from Western North America

The Anatomical Record, 2019

Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since th... more Poposaurus gracilis is a bipedal pseudosuchian archosaur that has been poorly understood since the discovery of the holotype fragmentary partial postcranial skeleton in 1915. Poposaurus. gracilis is a member of Poposauroidea, an unusually morphologically divergent clade of pseudosuchians containing taxa that are bipedal, quadrupedal, toothed, edentulous, and some individuals with elongated thoracic neural spines (i.e., sails). In 2003, a well preserved, fully articulated, and nearly complete postcranial skeleton of P. gracilis was discovered with some fragmentary cranial elements from the Upper Triassic Chinle Formation of Grand Staircase‐Escalante National Monument of southern Utah, USA. The aim of this work is to describe the osteology of this specimen in detail and compare P. gracilis to other closely related pseudosuchian archosaurs. The open neurocentral sutures throughout the majority of the vertebral column, the small size of this individual, and the presence of seven evenly spaced cyclic growth marks in the histologically sectioned femur indicate that this specimen was a skeletally immature juvenile, or subadult when it died. The pes of P. gracilis contains multiple skeletal adaptations and osteological correlates for soft tissue structures that support a hypothesis of digitigrady for this taxon. When coupled with the numerous postcranial characters associated with cursoriality, and the many anatomical traits convergent with theropod dinosaurs, this animal likely occupied a similar ecological niche with contemporaneous theropods during the Late Triassic Period. Anat Rec, 303:874–917, 2020. © 2019 American Association for Anatomy

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Research paper thumbnail of Pulmonary anatomy and a case of unilateral aplasia in a common snapping turtle (Chelydra serpentina ): developmental perspectives on cryptodiran lungs

Journal of Anatomy, 2017

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Vertebral morphometrics and lung structure in non-avian dinosaurs

Royal Society Open Science, 2018

The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds wh... more The lung-air sac system of modern birds is unique among vertebrates. However, debate surrounds whether an avian-style lung is restricted to birds or first appeared in their dinosaurian ancestors, as common osteological correlates for the respiratory system offer limited information on the lungs themselves. Here, we shed light on these issues by using axial morphology as a direct osteological correlate of lung structure, and quantifying vertebral shape using geometric morphometrics in birds, crocodilians and a wide range of dinosaurian taxa. Although fully avian lungs were a rather late innovation, we quantitatively show that non-avian dinosaurs and basal dinosauriforms possessed bird-like costovertebral joints and a furrowed thoracic ceiling. This would have immobilized the lung's dorsal surface, a structural prerequisite for a thinned blood-gas barrier and increased gas exchange potential. This could have permitted high levels of aerobic and metabolic activity in dinosaurs, eve...

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Research paper thumbnail of Cystic Calculus in a Laboratory-housed Green Anole (Anolis carolinensis)

Comparative medicine, 2017

An adult, male, wild-caught, laboratory-housed green anole (Anolis carolinensis) on a locomotor p... more An adult, male, wild-caught, laboratory-housed green anole (Anolis carolinensis) on a locomotor performance study was presented for anorexia. The anole exhibited a 26% weight loss and a thin body condition but was otherwise alert and active. Despite supportive care, the anole's clinical condition deteriorated, necessitating euthanasia. Postmortem examination revealed a 4.5 mm × 2.5-mm cystic calculus, which consisted entirely of sodium urate. Here we describe the clinical findings and locomotor consequences of this disease in a green anole. Although urolithiasis has been reported clinically in reptiles, this report presents the first case of a cystic calculus in a laboratory-housed green anole.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Correction: A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America

PloS one, 2015

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Pedal proportions of Poposaurus gracilis: convergence and divergence in the feet of archosaurs

Anatomical record (Hoboken, N.J. : 2007), 2014

The crocodile-line basal suchian Poposaurus gracilis had body proportions suggesting that it was ... more The crocodile-line basal suchian Poposaurus gracilis had body proportions suggesting that it was an erect, bipedal form like many dinosaurs, prompting questions of whether its pedal proportions, and the shape of its footprint, would likewise "mimic" those of bipedal dinosaurs. We addressed these questions through a comparison of phalangeal, digital, and metatarsal proportions of Poposaurus with those of extinct and extant crocodile-line archosaurs, obligate or facultatively bipedal non-avian dinosaurs, and ground birds of several clades, as well as a comparison of the footprint reconstructed from the foot skeleton of Poposaurus with known early Mesozoic archosaurian ichnotaxa. Bivariate and multivariate analyses of phalangeal and digital dimensions showed numerous instances of convergence in pedal morphology among disparate archosaurian clades. Overall, the foot of Poposaurus is indeed more like that of bipedal dinosaurs than other archosaur groups, but is not exactly like...

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Research paper thumbnail of Origin of the unique ventilatory apparatus of turtles

Nature Communications, 2014

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