{"refrec":{"BRefID":338129,"RR":"<b>Drage, H.B.; Vandenbroucke, T.R.A.; Van Roy, P.; Daley, A.C.</b> (2019). Sequence of post-moult exoskeleton hardening preserved in a trilobite mass moult assemblage from the Lower Ordovician Fezouata Konservat-Lagerstatte, Morocco. <i>Acta Palaeontol. Pol. 64(2)</i>: 261-273. <a href=\"https://hdl.handle.net/10.4202/app.00582.2018\" target=\"_blank\">https://hdl.handle.net/10.4202/app.00582.2018</a>","BEntID":334753,"PublicFlag":1,"CheckedFlag":1,"wosflag":1,"vabbflag":0,"RefStringPartII":". <i>Acta Palaeontol. Pol. 64(2)</i>: 261-273. <a href=\"https://hdl.handle.net/10.4202/app.00582.2018\" target=\"_blank\">https://hdl.handle.net/10.4202/app.00582.2018</a>","DocTypID":8,"DocType":"Journal article","MarineFlag":1,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Drage, H.B.; Vandenbroucke, T.R.A.; Van Roy, P.; Daley, A.C.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Drage, H.B. <i>et al.</i>","Englishabstract":"Euarthropods have a tough exoskeleton that provides crucial protection from predation and parasitism. However, this is restrictive to growth and must be periodically moulted. The moulting sequence is well-known from extant arthropods, consisting of: (i) the long inter-moult stage, in which no changes occur to the hardened exoskeleton; (ii) the pre-moult stage where the old exoskeleton is detached and the new one secreted; (iii) exuviation, when the old exoskeleton is moulted; and (iv) the post-moult stage during which the new exoskeleton starts as soft, thin, and partially compressed and gradually hardens to the robust exoskeleton of the inter-moult stage. Trilobite fossils typically consist of inter-moult carcasses or moulted exuviae, but specimens preserving the post-moult stage are rare. Here we describe nine specimens assigned to <em>Symphysurus ebbestadi</em> representing the first group of contemporaneous fossils collected that preserve all key stages of the moulting process in one taxon, including the post-moult stage. They were collected from a single lens in the Tremadocian part of the Fezouata Shale Formation, Morocco. Based on cephalic displacement and comparison to other trilobite moults, one specimen appears to represent a moulted exoskeleton. Four specimens are typical inter-moult carcasses. Four others are wrinkled and flattened, with thin exoskeletons compared to inter-moult specimens, and are considered post-moult individuals. These <em>S. ebbestadi</em> specimens illuminate the preservation and morphology of the post-moulting stage, characterised by strong anterior-posterior exoskeleton wrinkling, as well as overall body flattening and reduced visibility of thoracic articulations. Being found in the same lens, these specimens likely represent the first preserved in-the-act mass moulting event. The displayed sequence of moulting suggests the moulting process in trilobites was comparable to modern arthropods, and conserved within euarthropod evolutionary history.","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Sequence of post-moult exoskeleton hardening preserved in a trilobite mass moult assemblage from the Lower Ordovician Fezouata Konservat-Lagerstatte, Morocco","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2026-04-19 01:32:11.564237","timezone_type":1,"timezone":"+02:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"Trilobita; mass moult; soft-shelled; post-moult; moulting; exoskeleton; Ordovician; Morocco","OtherDescriptors":null,"Notes":null,"AnaPub":2019,"MonPub":null,"DateUpdate":"2021-05-31","DateCreate":"2021-05-17","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":"WOS:000470965100004","VABBcode":null,"OpenAcc":1,"Handle":"10.4202/app.00582.2018"},"refs":null,"anarec":{"AnaID":338129,"PubliDate":2019,"Pagination":"261-273","XtraPublOfAnaID":null,"ISBN":null,"Volume":"64","Issue":"2","BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":42022,"SerRR":"Acta Palaeontologica Polonica. 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