1
|
Iijima M, Mayerl CJ, Munteanu VD, Blob RW. Forelimb muscle activation patterns in American alligators: Insights into the evolution of limb posture and powered flight in archosaurs. J Anat 2024; 244:943-958. [PMID: 38242862 PMCID: PMC11095314 DOI: 10.1111/joa.14011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/21/2024] Open
Abstract
The evolution of archosaurs provides an important context for understanding the mechanisms behind major functional transformations in vertebrates, such as shifts from sprawling to erect limb posture and the acquisition of powered flight. While comparative anatomy and ichnology of extinct archosaurs have offered insights into musculoskeletal and gait changes associated with locomotor transitions, reconstructing the evolution of motor control requires data from extant species. However, the scarcity of electromyography (EMG) data from the forelimb, especially of crocodylians, has hindered understanding of neuromuscular evolution in archosaurs. Here, we present EMG data for nine forelimb muscles from American alligators during terrestrial locomotion. Our aim was to investigate the modulation of motor control across different limb postures and examine variations in motor control across phylogeny and locomotor modes. Among the nine muscles examined, m. pectoralis, the largest forelimb muscle and primary shoulder adductor, exhibited significantly smaller mean EMG amplitudes for steps in which the shoulder was more adducted (i.e., upright). This suggests that using a more adducted limb posture helps to reduce forelimb muscle force and work during stance. As larger alligators use a more adducted shoulder and hip posture, the sprawling to erect postural transition that occurred in the Triassic could be either the cause or consequence of the evolution of larger body size in archosaurs. Comparisons of EMG burst phases among tetrapods revealed that a bird and turtle, which have experienced major musculoskeletal transformations, displayed distinctive burst phases in comparison to those from an alligator and lizard. These results support the notion that major shifts in body plan and locomotor modes among sauropsid lineages were associated with significant changes in muscle activation patterns.
Collapse
Affiliation(s)
- Masaya Iijima
- Structure and Motion Lab, Department of Comparative Biomedical SciencesThe Royal Veterinary CollegeHertfordshireUK
- Nagoya University MuseumNagoyaJapan
| | | | - V. David Munteanu
- Department of Biological SciencesClemson UniversityClemsonSouth CarolinaUSA
| | - Richard W. Blob
- Department of Biological SciencesClemson UniversityClemsonSouth CarolinaUSA
| |
Collapse
|
2
|
Thinking Inside the Box: Comparative Limb Bone Shape in Emydid Turtles. J HERPETOL 2021. [DOI: 10.1670/20-086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
3
|
Sellers WI, Rose KAR, Crossley DA, Codd JR. Inferring cost of transport from whole-body kinematics in three sympatric turtle species with different locomotor habits. Comp Biochem Physiol A Mol Integr Physiol 2020; 247:110739. [PMID: 32446940 DOI: 10.1016/j.cbpa.2020.110739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 11/19/2022]
Abstract
Chelonians are mechanically unusual vertebrates as an exoskeleton limits their body wall mobility. They generally move slowly on land and have aquatic or semi-aquatic lifestyles. Somewhat surprisingly, the limited experimental work that has been done suggests that their energetic cost of transport (CoT) are relatively low. This study examines the mechanical evidence for CoT in three turtle species that have differing degrees of terrestrial activity. Our results show that Apolone travels faster than the other two species, and that Chelydra has higher levels of yaw. All the species show poor mean levels of energy recovery, and, whilst there is considerable variation, never show the high levels of energy recovery seen in cursorial quadrupeds. The mean mechanical CoT is 2 to 4 times higher than is generally seen in terrestrial animals. We therefore find no mechanical support for a low CoT in these species. This study illustrates the need for research on a wider range of chelonians to discover whether there are indeed general trends in mechanical and metabolic energy costs.
Collapse
Affiliation(s)
- William I Sellers
- Department of Earth and Environmental Sciences, University of Manchester, UK.
| | | | | | | |
Collapse
|
4
|
Pereyra ME, Bona P, Cerda IA, Desántolo B. Osteohistological correlates of muscular attachment in terrestrial and freshwater Testudines. J Anat 2019; 234:875-898. [PMID: 30901084 DOI: 10.1111/joa.12975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2019] [Indexed: 12/01/2022] Open
Abstract
Sharpey's fibers are considered the anatomical structures integrated to the muscles. Since these fibers leave marks at the microscopic level, their presence and distribution are used as evidence of muscle attachment in extinct and extant forms. In recent years, studies have been focusing on muscle-bone and tendon-bone interaction mostly on mammals. The main objective of this work is to contribute to the morphological and histological knowledge of muscle attachment in other amniotes, such as reptiles, and their variation related to different locomotor habits. In this way, a study was performed on terrestrial and aquatic turtles. The musculature related to the movement of the humerus, and pectoral girdle in Chelonoidis chilensis, Phrynops hilarii and Hydromedusa tectifera was analyzed. Dissections were performed mapping the origins and insertions of each muscle and undecalcified thin sections were performed in specific muscular attachment sites. We found some differences which were not previously reported, related to the insertion of the m. pectoralis, the m. coracobrachialis magnus and the origin of the m. tractor radii. The osteohistology revealed the presence of Sharpey's fibers in the cortex of all the bone elements analyzed. Patterns were established in relation to the orientation and density of Sharpey's fibers, which were used for the categorization of each muscle attachment site. The comparative micro-anatomical study of these areas did not reveal any important differences between terrestrial and freshwater turtles in muscles involved with the rotation, abduction and adduction of the humerus. In this way, the preliminary results suggest an absence of correlation between the distribution and density of Sharpey's fibers between different habitat forms, at least in the bones and species analyzed.
Collapse
Affiliation(s)
- María Eugenia Pereyra
- División Paleontología Vertebrados, Museo de La Plata (Unidad de Investigación Anexo), Facultad de Ciencias Naturales y Museo, CONICET, Buenos Aires, Argentina
| | - Paula Bona
- División Paleontología Vertebrados, Museo de La Plata (Unidad de Investigación Anexo), Facultad de Ciencias Naturales y Museo, CONICET, Buenos Aires, Argentina
| | - Ignacio Alejandro Cerda
- Instituto de Investigaciones en Paleobiología y Geología, Universidad Nacional de Río Negro y Museo Carlos Ameghino, CONICET, Cipolletti, Argentina
| | - Bárbara Desántolo
- Cátedra de Citología, Histología y Embriología A, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Buenos Aires, Argentina
| |
Collapse
|
5
|
Cuff AR, Daley MA, Michel KB, Allen VR, Lamas LP, Adami C, Monticelli P, Pelligand L, Hutchinson JR. Relating neuromuscular control to functional anatomy of limb muscles in extant archosaurs. J Morphol 2019; 280:666-680. [PMID: 30847966 DOI: 10.1002/jmor.20973] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 12/21/2022]
Abstract
Electromyography (EMG) is used to understand muscle activity patterns in animals. Understanding how much variation exists in muscle activity patterns in homologous muscles across animal clades during similar behaviours is important for evaluating the evolution of muscle functions and neuromuscular control. We compared muscle activity across a range of archosaurian species and appendicular muscles, including how these EMG patterns varied across ontogeny and phylogeny, to reconstruct the evolutionary history of archosaurian muscle activation during locomotion. EMG electrodes were implanted into the muscles of turkeys, pheasants, quail, guineafowl, emus (three age classes), tinamous and juvenile Nile crocodiles across 13 different appendicular muscles. Subjects walked and ran at a range of speeds both overground and on treadmills during EMG recordings. Anatomically similar muscles such as the lateral gastrocnemius exhibited similar EMG patterns at similar relative speeds across all birds. In the crocodiles, the EMG signals closely matched previously published data for alligators. The timing of lateral gastrocnemius activation was relatively later within a stride cycle for crocodiles compared to birds. This difference may relate to the coordinated knee extension and ankle plantarflexion timing across the swing-stance transition in Crocodylia, unlike in birds where there is knee flexion and ankle dorsiflexion across swing-stance. No significant effects were found across the species for ontogeny, or between treadmill and overground locomotion. Our findings strengthen the inference that some muscle EMG patterns remained conservative throughout Archosauria: for example, digital flexors retained similar stance phase activity and M. pectoralis remained an 'anti-gravity' muscle. However, some avian hindlimb muscles evolved divergent activations in tandem with functional changes such as bipedalism and more crouched postures, especially M. iliotrochantericus caudalis switching from swing to stance phase activity and M. iliofibularis adding a novel stance phase burst of activity.
Collapse
Affiliation(s)
- Andrew R Cuff
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| | - Monica A Daley
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| | - Krijn B Michel
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| | - Vivian R Allen
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| | - Luis Pardon Lamas
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| | - Chiara Adami
- Queen Mother Hospital, Department of Clinical Science and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, United Kingdom
| | - Paolo Monticelli
- Queen Mother Hospital, Department of Clinical Science and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, United Kingdom
| | - Ludo Pelligand
- Queen Mother Hospital, Department of Clinical Science and Services, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, United Kingdom
| | - John R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, North Mymms, Hertfordshire, AL9 7TA, United Kingdom
| |
Collapse
|
6
|
Blob RW, Mayerl CJ, Rivera ARV, Rivera G, Young VKH. "On the Fence" versus "All in": Insights from Turtles for the Evolution of Aquatic Locomotor Specializations and Habitat Transitions in Tetrapod Vertebrates. Integr Comp Biol 2016; 56:1310-1322. [PMID: 27940619 DOI: 10.1093/icb/icw121] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Though ultimately descended from terrestrial amniotes, turtles have deep roots as an aquatic lineage and are quite diverse in the extent of their aquatic specializations. Many taxa can be viewed as "on the fence" between aquatic and terrestrial realms, whereas others have independently hyperspecialized and moved "all in" to aquatic habitats. Such differences in specialization are reflected strongly in the locomotor system. We have conducted several studies to evaluate the performance consequences of such variation in design, as well as the mechanisms through which specialization for aquatic locomotion is facilitated in turtles. One path to aquatic hyperspecialization has involved the evolutionary transformation of the forelimbs from rowing, tubular limbs with distal paddles into flapping, flattened flippers, as in sea turtles. Prior to the advent of any hydrodynamic advantages, the evolution of such flippers may have been enabled by a reduction in twisting loads on proximal limb bones that accompanied swimming in rowing ancestors, facilitating a shift from tubular to flattened limbs. Moreover, the control of flapping movements appears related primarily to shifts in the activity of a single forelimb muscle, the deltoid. Despite some performance advantages, flapping may entail a locomotor cost in terms of decreased locomotor stability. However, other morphological specializations among rowing species may enhance swimming stability. For example, among highly aquatic pleurodiran turtles, fusion of the pelvis to the shell appears to dramatically reduce motions of the pelvis compared to freshwater cryptodiran species. This could contribute to advantageous increases in aquatic stability among predominantly aquatic pleurodires. Thus, even within the potential constraints of a body plan in which the body is encased by a shell, turtles exhibit diverse locomotor capacities that have enabled diversification into a wide range of aquatic habitats.
Collapse
Affiliation(s)
- Richard W Blob
- *Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA
| | | | | | - Gabriel Rivera
- Department of Biology, Creighton University, Omaha, NE, 68178, USA
| | - Vanessa K H Young
- *Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA
| |
Collapse
|
7
|
Abstract
How can snakes and robots move up sandy slopes?
[Also see Report by
Marvi
et al.
]
Collapse
Affiliation(s)
- John J Socha
- Biomedical Engineering and Mechanics, Virginia Tech, 495 Old Turner Street, Blacksburg, VA 24061, USA.
| |
Collapse
|