caa a22 4500 388016930 CHVBK 20180307124913.0 cr unu---uuuuu 161130e199807 xx s 000 0 eng 10.1017/S0022336000040361 doi S0022336000040361 pii (NATIONALLICENCE)cambridge-10.1017/S0022336000040361 Brood pouches in trilobites [Elektronische Daten] [Richard A. Fortey, Nigel C. Hughes] During the Cambrian and Ordovician trilobites belonging to a variety of clades developed distinctive inflated bulbs on the preglabellar field. We make the case that these bulbs were brood pouches, which were employed for retaining and protecting larval trilobites in order to ensure a higher rate of survivorship. Living arthropods of several classes develop comparable spherical structures—for example the domicilium of certain ostracodes. Living limuloids, likely the trilobites' closest living relatives, carry large and yolky eggs in an homologous, prelabral site. There are some trilobite examples where "species pairs” found in the same fossil sites appear to differ only in the presence or absence of the preglabellar bulb. These may represent the female and male of a single species, respectively. If so, this is the first well-supported case of sexual dimorphism in trilobites. Some more problematic examples are discussed, where alleged dimorphism would have to be more extreme. Copyright © The Paleontological Society Fortey Richard A. Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom, <raf@nhm.ac.uk> aut Hughes Nigel C. Department of Earth Sciences, University of California, Riverside, 92521, <nigel.hughes@ucr.edu> aut Journal of Paleontology Cambridge University Press 72/4(1998-07), 638-649 0022-3360 72:4<638 1998 72 JPA https://doi.org/10.1017/S0022336000040361 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0022336000040361 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fortey Richard A. Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom, <raf@nhm.ac.uk> aut NATIONALLICENCE 700 1- Hughes Nigel C. Department of Earth Sciences, University of California, Riverside, 92521, <nigel.hughes@ucr.edu> aut NATIONALLICENCE 773 0- Journal of Paleontology Cambridge University Press 72/4(1998-07), 638-649 0022-3360 72:4<638 1998 72 JPA CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge