Techniques of trilobite exuviation
- 1 April 1984
- journal article
- research article
- Published by Scandinavian University Press / Universitetsforlaget AS in Lethaia
- Vol. 17 (2) , 153-173
- https://doi.org/10.1111/j.1502-3931.1984.tb01722.x
Abstract
Examples of the [Cambrian and Ordovician] trilobites Toxochasmops extensus (Boeck, 1838), Asaphiscus wheeleri Meek, 1874, Encrinurus mitchelli Foerste, 1888, Ogygopsis klotzi (Rominger, 1887), Paradoxides davidis Salter, 1863 and Oryctocephalus spp., which are interpreted as exuvial configurations, are described. Four specimens of T. extensus are known in which the pygidium rests either directly behind the cephalon, or with only 3 intervening thoracic segments. During exuviation the old pygidium became wedged behind the cephalon. This facilitated its removal. An ecdysial configuration of A. wheeleri is described which possesses inverted and partially rotated free cheeks. Part of the thorax of the specimen is wedged obliquely behind the cephalon. This is considered to have aided withdrawal of the trilobite from its exoskeleton. Two specimens of E. mitchelli are described which possess free cheeks inverted beneath the cranidium by lateral rotation, in a manner similar to that of A. wheeleri. Three examples of Ogygopsis klotzi are described, one a failed exuvia and two in which the free cheeks were inverted and rotated through 180.degree. with respect to their original position and came to rest beneath the thorax. An identical exuvia of P. trapezopyge is also described. Two specimens of Oryctocephalus exhibiting 2 different arrangements of inverted free cheeks are recorded. Possible mechanisms for each of these free cheek inversions are proposed.Keywords
This publication has 13 references indexed in Scilit:
- Structure, patterns and function of cuticular terraces in trilobitesLethaia, 1981
- The post-ecdysial development of the cuticle and the eye of the Devonian trilobitePhacops rana milleriStewart 1927Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 1980
- Molting and GrowthPublished by Elsevier ,1980
- Taxonomy and distribution of chasmopine trilobitesGeological Magazine, 1980
- Evolutionary trends and their functional significance in chasmopine trilobitesLethaia, 1980
- Morphology and function of cuticular micro-scales and corresponding structures in terrestrial isopods (Crust., Isop., Oniscoidea)Zoomorphology, 1978
- Structure, patterns, and function of cuticular terraces in recent and fossil arthropodsZoomorphology, 1978
- Structure and function of trilobite terrace linesPublished by Scandinavian University Press / Universitetsforlaget AS ,1975
- Moulting in trilobitesPublished by Scandinavian University Press / Universitetsforlaget AS ,1975
- Fabricational Noise in Adaptive MorphologySystematic Zoology, 1973