Vestibular evidence for the evolution of aquatic behaviour in early cetaceans

Title

Vestibular evidence for the evolution of aquatic behaviour in early cetaceans

Creator

Spoor F; Bajpal S; Hussaim S T; Kumar K; Thewissen J G M

Publisher

Nature

Date

2002
2002-05

Description

Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton(1). 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(2). Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times smaller than in other mammals. This reduces the sensitivity of the canal system, most plausibly to match the fast body rotations that characterize cetacean behaviour. Eocene fossils show that the new sensory regime, incompatible with terrestrial competence, developed quickly and early in cetacean evolution, as soon as the taxa are associated with marine environments. Dedicated agile swimming of cetaceans thus appeared to have originated as a rapid and fundamental shift in locomotion rather than as the gradual transition suggested by postcranial evidence. We hypothesize that the unparalleled modification of the semicircular canal system represented a key 'point of no return' event in early cetacean evolution, leading to full independence from life on land.

Subject

artiodactyls; bony labyrinth; feet; hearing; inner-ear; locomotor evolution; model; origin; petrosal; Science & Technology - Other Topics; whales

Identifier

Format

Journal Article

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Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

163-166

Issue

6885

Volume

417

Citation

Spoor F; Bajpal S; Hussaim S T; Kumar K; Thewissen J G M, “Vestibular evidence for the evolution of aquatic behaviour in early cetaceans,” NEOMED Bibliography Database, accessed November 30, 2021, https://neomed.omeka.net/items/show/7215.

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