Version of Record online: 25 MAR 2009
© 2009 The Authors, Journal compilation © 2009 The Lethaia Foundation
Volume 42, Issue 3, pages 357–364, September 2009
How to Cite
VINTHER, J. and BRIGGS, D. E.G. (2009), Machaeridian locomotion. Lethaia, 42: 357–364. doi: 10.1111/j.1502-3931.2009.00165.x
- Issue online: 23 JUL 2009
- Version of Record online: 25 MAR 2009
- manuscript received on 01/05/2008; manuscript accepted on 29/09/2008.
- hydrostatic skeleton;
The discovery that machaeridians (class Machaeridia Withers, 1926) are annelids allows their mode of locomotion to be interpreted in the context of the body plan of this phylum. The Plumulitidae were errant epibenthic forms, moving with parapodia. The body of Turrilepadidae and Lepidocoleidae, however, was enclosed largely within the mineralized plates that make up the skeleton. Articulated specimens indicate that these machaeridians were able to burrow like other annelids using peristaltic locomotion. A lepidocoleid specimen indicates that multiple waves of shortened and contracted regions moved over the body. This is in contrast to the mode of locomotion in earthworms and most polychaetes, but similar to peristaltic progression in Polyphysia (Scalibregmidae). Either the rugose sculpture (turrilepadids) and/or the margins of the overlapping shell plates functioned as a burrowing sculpture, allowing forward movement but preventing backwards slipping. A trace from the Devonian Hunsrück Slate associated with a lepidocoleid indicates that considerable flexing of the skeleton was possible, but this is an escape trace and does not represent normal locomotion. Features of the skeleton of machaeridians are convergent on those of molluscs where the shells likewise function in protection and burrowing.