Cardiovascular Physiology of Dinosaurs

Seymour, Roger S.

doi:10.1152/physiol.00016.2016

Cited by 23 publications

(29 citation statements)

References 105 publications

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“…Bone isotope analysis (Tutken, ) confirms the modern consensus that sauropods were predominantly terrestrial browsers not adapted to frequently exploit aquatic vegetation (contra Stevens and Parrish, ,b; Seymour, ). Nor were their unpadded forefeet well adapted for traversing soft substrates, as evidenced by the remains of mired sauropods (Russell et al, ; Heinrich et al, ).…”

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 62%

“…Because giraffes increasingly elevate circulatory pressures well above the avian‐mammalian norm as they increasingly raise their heads (Mitchell and Skinner, ), it is likely that sauropods did the same. Most researchers agree that if sauropods regularly raised their heads much further above their hearts than giraffes, then the dinosaurs' maximum circulatory pressures were even higher (Paul, ; Stevens and Parrish, ; Seymour and Lillywhite, ; Faarc, ; Seymour, ; Sander et al, ; Seymour, ; Seymour and Lillywhite, ). In principle very tall sauropods could have avoided the need for blood pressures above the giraffe maximum if they did not raise their heads much above the maximum giraffe head/heart height differential for more than a few moments at a time.…”

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

“…The hypothesis of terramegathermy proposes that land vertebrates over 1 tonne and a maximum height above the heart of significantly over halft a meter must have resting and exercise metabolic rates above the reptilian level (Paul, , ; Seymour, makes a similar argument), this effect increases with height. Contrary to earlier reports, giraffe hearts are not enlarged relative to total mass compared to animals of normal height (Mitchell and Skinner, ), so calculations that very tall sauropods would have needed extremely large hearts (Seymour and Lillywhite, ; Paul, ; Seymour, ) may be exaggerated.…”

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

“…Contrary to earlier reports, giraffe hearts are not enlarged relative to total mass compared to animals of normal height (Mitchell and Skinner, ), so calculations that very tall sauropods would have needed extremely large hearts (Seymour and Lillywhite, ; Paul, ; Seymour, ) may be exaggerated. Even so, the cardiac work needed to generate high pressures should have increased the metabolic rates of very tall sauropods significantly over the levels needed if the same animals had shorter necks (Paul, ; Seymour and Lillywhite, ; Seymour, ; Sander et al, ; Seymour, ), although it is possible that alternative adaptations may be reduced the costs. The claim by Seymour () that the energy needed to circulate blood in a very tall animal with elevated circulatory pressure is the same regardless of neck posture appears to be contradicted by the lower pressures associated with lower necks.…”

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

“…The pose and vertical reach of the often very long necks of sauropods has become an active and controversial area of research (Bakker, ; Borsuk‐Bialynicka, ; Martin, ; Paul, ,b, 2000, ; Tanimoto, ; McIntosh et al, ; Jensen, ; Christian and Heinrich, ; Martin et al, ; Parrish and Stevens, ; Stevens and Parrish, , , ; Seymour and Lillywhite, ; Upchurch, ; Wedel et al, ; Barrett and Willis, ; Stevens, ; Christian, ; Christian and Dzemski, ; Dzemski and Christian, ; Sereno et al, ; Faarc, ; Mallison, ; Sander et al, ; Seymour, ; Taylor et al, ; Mallison, ; Remes et al, ; Siegwarth et al, ; Ruxton and Wilkinson, ; Whitlock, ; Wilkinson and Ruxton ; Colbey et al, ; Carabajal et al, ; Taylor, ; Hallett and Wedel, ; Seymour, ; Taylor and Wedel, ; Woodruff, ). A research group was formed in part to address the problem (Sander and Clauss, ; Sander et al, ).…”

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confidence: 99%

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Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs

Paul

2017

The Anatomical Record

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The ongoing controversy centered on neck posture and function in sauropod dinosaurs is misplaced for a number of reasons. Because of an absence of pertinent data it is not possible to accurately restore the posture and range of motion in long necked fossil animals, only gross approximations are possible. The existence of a single "neutral posture" in animals with long, slender necks may not exist, and its relationship to feeding habits is weak. Restorations of neutral osteological neck posture based on seemingly detailed diagrams of cervical articulations are not reliable because the pictures are not sufficiently accurate due to a combination of illustration errors, and distortion of the fossil cervicals. This is all the more true because fossil cervical series lack the critical inter-centra cartilage. Maximum vertical reach is more readily restorable and biologically informative for long necked herbivores. Modest extension of 10° between each caudal cervical allowed high shouldered sauropods to raise the cranial portion of their necks to vertical postures that allowed them to reach floral resources far higher than seen in the tallest mammals. This hypothesis is supported by the dorsally extended articulation of the only known co-fused sauropod cervicals. Many sauropods appear to have been well adapted for rearing in order to boost vertical reach, some possessed retroverted pelves that may have allowed them to walk slowly while bipedal. A combination of improved high browsing abilities and sexual selection probably explains the unusually long necks of tall ungulates and super tall sauropods. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:1802-1825, 2017. © 2017 Wiley Periodicals, Inc.

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Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 62%

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

Section: Biological and Ecological Implications For The Competing Hypmentioning

confidence: 99%

mentioning

confidence: 99%

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Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs

Paul

2017

The Anatomical Record

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Scaling of major organs in hatchling female American alligators (Alligator mississippiensis)

et al. 2018

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Allometric equations represent relationships between morphological/physiological traits and body mass Y = aM b , where Y is the trait, a is elevation, b is the exponent describing the shape of the line, and M is body mass. We measured visceral organ masses in hatchling alligators (Alligator mississippiensis) from five clutches from approximately 45 to 500 g wet body mass. The interaction between initial egg mass and clutch identity was significant for initial hatchling mass, but only egg mass, not clutch, had a significant effect on initial snout-vent and head length. Kidney and liver mass showed biphasic scaling with body mass, as determined by "breakpoint" analyses, with the breakpoint at 120 g wet body mass. Kidney and liver wet mass showed slopes b > 1.0 as animals increased approximately 45-120 g, with significantly lower b approximately 0.8-0.9 for alligators 120-500 g. Within kidney and liver mass, below and above the breakpoint, organ mass slopes tended to be similar across clutches. Lung and heart wet mass did not show biphasic scaling, with b approximately 0.8-0.9. Within lung and heart mass, clutches had statistically identical slopes. Combined clutch data for wet mass showed distinct regressions with b > 1.4 for approximately 45-120 g alligators' kidney and liver mass, compared with approximately 120-500 g alligators' kidney, liver, lung, and heart mass b < 1.0.Alligators show rapid kidney and liver growth following hatching, with higher rates than lung or heart tissue. Clutch, egg mass, and hatchling size influence organ size, and each factor should be accounted for in future studies exploring reptile morphology and physiology to assess environmental versus clutch contributions. K E Y W O R D S allometry, bird, body size, dinosaur, organ mass, reptile 1 | INTRODUCTION The effect of body mass on the relative growth, metabolism, organ size, and morphological/anatomical features of animals is an active and long-studied area of biology, ecology, and comparative animal physiology (Franz et al.Wiersma, Nowak, & Williams, 2012). Allometry is used to demonstrate nonlinear relationships between body mass and physiological rates or morphological variables, across both interspecific and intraspecific changes in body mass. Allometric relationships between morphological or physiological traits and body mass are represented using the equation Y = aM b . Y is a size or rate, a is elevation, b is the exponent describing the shape of the line, M is body mass, and the rate of change (slope) can be allometric (b < 1.0 or b > 1.0) or J. Exp. Zool. 2019;331:38-51. wileyonlinelibrary.com/journal/jez

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Nasal turbinates of the dicynodont Kawingasaurus fossilis and the possible impact of the fossorial habitat on the evolution of endothermy

Laaß,

Kaestner

2023

Journal of Morphology

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The nasal region of the fossorial anomodont Kawingasaurus fossilis was virtually reconstructed from neutron‐computed tomographic data and compared with the terrestrial species Pristerodon mackayi and other nonmammalian synapsids. The tomography of the Kawingasaurus skull reveals a pattern of maxillo‐, naso‐, fronto‐ and ethmoturbinal ridges that strongly resemble the mammalian condition. On both sides of the nasal cavity, remains of scrolled maxilloturbinals were preserved that were still partially articulated with maxilloturbinal ridges. Furthermore, possible remains of the lamina semicircularis as well as fronto‐ or ethmoturbinals were found. In Kawingasaurus, the maxilloturbinal ridges were longer and stronger than in Pristerodon. Except for the nasoturbinal ridges, no other ridges in the olfactory region and no remains of turbinates were recognized. This supports the hypothesis that naso‐, fronto‐, ethmo‐ and maxilloturbinals were a plesiomorphic feature of synapsids, but due to their cartilaginous nature in most taxa were, in almost all cases, not preserved. The well‐developed maxilloturbinals in Kawingasaurus were probably an adaptation to hypoxia‐induced hyperventilation in the fossorial habitat, maintaining the high oxygen demands of Kawingasaurus' large brain. The surface area of the respiratory turbinates in Kawingasaurus falls into the mammalian range, which suggests that they functioned as a countercurrent exchange system for thermoregulation and conditioning of the respiratory airflow. Our results suggest that the environmental conditions of the fossorial habitat led to specific sensory adaptations, accompanied by a pulse in brain evolution and of endothermy in cistecephalids, ~50 million years before the origin of endothermy in the mammalian stem line. This supports the Nocturnal Bottleneck Theory, in that we found evidence for a similar evolutionary scenario in cistecephalids as proposed for early mammals.

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Cardiovascular Physiology of Dinosaurs

Cited by 23 publications

References 105 publications

Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs

Restoring Maximum Vertical Browsing Reach in Sauropod Dinosaurs

Scaling of major organs in hatchling female American alligators (Alligator mississippiensis)

Nasal turbinates of the dicynodont Kawingasaurus fossilis and the possible impact of the fossorial habitat on the evolution of endothermy

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