Revision of the enrolment in Spanish Cambrian trilobites and its implications in trilobite evolution

The middle Cambrian trilobites found in the locality of Purujosa as well as other localities from the Iberian Chains such as Murero and Mesones (Zaragoza) show a large number of new enrolment devices as well as high variability of enrolment types ever describe in Cambrian times, they show that enrolment was a very spread behavior in Cambrian times. In this paper I carried out a revision of the coaptative structures or interlocking devices, which are in the cephalon and in the pigidia, as well as a revision of the articulating devices through the thorax needed for enrolment. The different enrolment types are described and discussed with special emphasis in Cambrian trilobites. For first time enrolled specimens of Agraulos longicephalus and Ctenocephalus antiquus are figured. I describe the different enrolled trilobites found in the locality of Purujosa such as Solenopleuropsis, Pardailhania, Schopfaspis?, Agraulos, Ctenocephalus and Eccaparadoxides. Finally I discuss the importance of such behavior for trilobite evolution.