title: Hydrodynamics of fossil fishes.
abstract: From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms.
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK tomfletcher.palaeo@gmail.com.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fletcher
authors.affiliation: School of Biology, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
authors.forename: John
authors.initials: J
authors.lastname: Altringham
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Peakall
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Wignall
authors.affiliation: School of Earth and Environment, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Dorrell
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D005399:Fishes / Q000033:anatomy & histology* / Q000502:physiology*; D005580:Fossils / Q000033:anatomy & histology*; D057446:Hydrodynamics; D013550:Swimming
keywords: biomechanics; comparative anatomy; fishes; functional morphology; hydrodynamics; locomotion