Vestibular evidence for the evolution of aquatic behaviour in early cetaceans

@article{Spoor2002VestibularEF,
  title={Vestibular evidence for the evolution of aquatic behaviour in early cetaceans},
  author={Fred Spoor and Sunil Bajpai and S. Taseer Hussain and K Ravi Kumar and J. G. M. Thewissen},
  journal={Nature},
  year={2002},
  volume={417},
  pages={163-166}
}
Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton. Here we assess the evolution of cetacean locomotor behaviour from an independent perspective by looking at the semicircular canal system, one of the main sense organs involved in neural control of locomotion. Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times… 

Comparative analysis of vestibular ecomorphology in birds

The hypothesis that the lengths, streamlines and angles between the semicircular canals are related to body size, wing kinematics and flying style in birds is tested and a link between visual acuity and proportional size of the labyrinth among birds is tentatively indicated.

Deep evolutionary diversification of semicircular canals in archosaurs

The relationship of head movements to semicircular canal size in cetaceans

Comparisons of rotational head velocities, frequencies and accelerations of bottlenose dolphin and cattle using an array of three orthogonal head-fixed miniaturized rotational ratemeters indicate that accentuated head movements cannot explain the reduced size and sensitivity of cetacean semicircular canals.

Inner ear sensory system changes as extinct crocodylomorphs transitioned from land to water

The morphology of the vestibular system corresponds to habitat, with pelagic thalattosuchians exhibiting a more compact labyrinth with wider semicircular canal diameters and an enlarged vestibule, reminiscent of modified and miniaturized labyrinths of other marine reptiles and cetaceans.

Functional Morphology of the Vertebral Column in Remingtonocetus (Mammalia, Cetacea) and the Evolution of Aquatic Locomotion in Early Archaeocetes.

It is suggested that the evolution of tail-powered swimming in early cetaceans was preceded by an increase in lumbar mobility, and the vertebral morphology of an early archaeocete (Remingtonocetus domandaensis) is documents and quantitative methods for assessing vertebral function in fossil forms are developed.

Transition of Eocene Whales from Land to Sea: Evidence from Bone Microstructure

This study highlights the strong need for homologous sections in comparative microanatomical studies, and the importance of combining information from several bones of the same taxon for improved functional interpretation.

The inner ear of Megatherium and the evolution of the vestibular system in sloths

The morphometric analyses demonstrate that the giant ground sloth clearly departs from the SC morphology of both extant sloth genera (Choloepus, Bradypus) and is in some aspects closer to that of armadillos and anteaters.

The Evolution of Bat Vestibular Systems in the Face of Potential Antagonistic Selection Pressures for Flight and Echolocation

Across all bats, the shape of the anterior and lateral canals was associated with large cochlea size and small body size respectively, suggesting differential spatial constraints on each canal depending on its orientation within the skull, thus in many echolocating bats, it seems that the combination of smallBody size and enlarged cochlear size together act as a principal force on the vestibular system.

Carnivoran hunting style and phylogeny reflected in bony labyrinth morphometry

The results demonstrate that the bony labyrinth provides a powerful ecological proxy reflecting both predatory habits as well as phylogenetic relationships in extinct and extant carnivorans.

An Integrative Investigation of Convergent Bipedal Locomotion in Desert Rodents

This thesis integrates phylogenetics, functional morphology, biomechanics, information theory, and behavior to investigate whether and how bipedality increases fitness in desert ecosystems, and whether bipedal rodents convergently evolved to have the role in their respective ecosystems.
...

References

SHOWING 1-10 OF 38 REFERENCES

Implications of Vertebral Morphology for Locomotor Evolution in Early Cetacea

Although almost invariably fragmentary, early cetacean postcranial skeletons are surprisingly informative, and can complement morphological indicators of diet, sensory specializations, and skull reorganization to fill in some of the gaps in the authors' understanding of the dramatic transition of earlyCetaceans as they moved from land to water.

Fossil Evidence for the Origin of Aquatic Locomotion in Archaeocete Whales

The fossil indicates that archaic whales swam by undulating their vertebral column, thus forcing their feet up and down in a way similar to modern otters.

Locomotor evolution in the earliest cetaceans: functional model, modern analogues, and paleontological evidence

It is concluded that Ambulocetus may have locomoted by a combination of pelvic paddling and dorsoventral undulations of the tail, and that its locomotor mode in water resembled that of the modern otter Lutra most closely.

Hearing in extinct cetaceans as determined by cochlear structure

The bony cochlea is described in representative Odontoceti, Mysticeti and Archaeoceti, with special emphasis on adaptations to high-frequency echolocation. The latter include (a) a small distance

Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls

Cladistic analysis of the skeletons of two early Eocene pakicetid cetaceans, the fox-sized Ichthyolestes pinfoldi, and the wolf-sized Pakicetus attocki, indicates that cetACEans are more closely related to artiodactyls than to any mesonychian, and supports monophyly of artiodACTyls.

Comparative review of the human bony labyrinth.

This review compares the bony labyrinth of humans with that of the great apes and 37 other primate species based on data newly acquired with computed tomography combined with previous descriptions, finding that labyrinthine and basicranial shape are interspecifically correlated in the sample, and in most respects the human morphology is consistent with the general trend among primates.

Endocranial Volume of Mid-Late Eocene Archaeocetes (Order: Cetacea) Revealed by Computed Tomography: Implications for Cetacean Brain Evolution

The large brain of modern cetaceans has engendered much hypothesizing about both the intelligence of cetaceans (dolphins, whales, and porpoises) and the factors related to the evolution of such large

Structural Adaptations of Early Archaeocete Long Bones

Early archaeocete postcranial skeletons should document the series of structural modifications that occurred in a move from complete terrestrial competence, through an amphibious or semiaquatic stage, to the type of highly specialized aquatic locomotion that characterizes modern cetaceans.

Postcranial Osteology of the North American Middle Eocene Protocetid Georgiacetus

The purpose of this report is to describe the postcranial remains of G. vogtlensis and compare them with those of other archaeocetes.

Paleobiological Perspectives on Mesonychia, Archaeoceti, and the Origin of Whales

Living cetaceans share a suite of special characteristics related to life in water that distinguish them from land mammals: These include large body size, a reduced and simplified dentition, an audition-dominated sensory and communication system, a hydrodynamically streamlined body form with a muscular propulsive tail.