caa a22 4500 388110392 CHVBK 20180307125352.0 cr unu---uuuuu 161130s1999 xx s 000 0 eng 10.1017/S0263593300007203 doi S0263593300007203 pii (NATIONALLICENCE)cambridge-10.1017/S0263593300007203 The ontogeny of Taihungshania miqueli (Bergeron, 1893) from the Arenig of the Montagne Noire, southern France [Elektronische Daten] The very large trilobite Taihungshania miqueli occurs abundantly in siliceous nodules in the Ordovician of the Montagne Noire, southern France, but in these, larval individuals are not preserved. At a new locality at Peret, near Cabrières, protaspid and early meraspid growth stages occur in great abundance, together with a few complete specimens belonging to meraspid degrees 1, 2, 3, 5 and 7, and a single young holaspis. Although this material is largely flattened, and the originally globular protaspides crushed, it is still possible to establish the development of several axial rings before the transitory pygidium becomes liberated. In the degree 0 meraspis, the cephalon and transitory pygidium are about the same size, and the presence of a partially enrolled degree 3 meraspis indicates that protective coiling was possible by this early stage. Palpebral lobes are incipient in degree 2 meraspides, and fully formed by degree 7, otherwise the morphology of the cephalon becomes quite adult-like by degree 4. The pygidial spines begin to appear in degree 5, at which stage there are about 10 axial rings; there are about 13 in a degree 7 meraspis, and in the adult, where the posterior contour is semi-elliptical, there are some 22. The smallest hypostomes present belong to a degree 6 meraspis, and these are morphologically similar to those of adults. Observations on the later growth stages were made on material from another locality (Caramaou), as well as that from Peret. In the eye the upper lenses are large and slightly separated, but those towards the base are much diminished in size; this is a function of an unusual growth geometry. At Peret, all stages of development, at least as far as young adults, are represented, albeit often in a fragmentary state. As with other asaphines, the protaspides are assumed to be planktic, and T. miqueli presumably left the plankton and became benthic between the protaspid and meraspid periods. Copyright © Royal Society of Edinburgh 1999 eyes nationallicence hypostome nationallicence meraspis nationallicence Ordovician nationallicence pygidium nationallicence trilobites nationallicence Berard Pierre Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K. Clarkson Euan N. K. Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K. Taylor Cecilia M. Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K. Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/2(1999), 147-163 0263-5933 90:2<147 1999 90 TRE https://doi.org/10.1017/S0263593300007203 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0263593300007203 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Berard Pierre Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K NATIONALLICENCE 700 1- Clarkson Euan N. K. Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K NATIONALLICENCE 700 1- Taylor Cecilia M. Department of Geology and Geophysics, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JW, U.K NATIONALLICENCE 773 0- Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/2(1999), 147-163 0263-5933 90:2<147 1999 90 TRE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge