Behavior of Jince drumian trilobites

This publication represents a report of the findings of a scientifically interesting collection of trilobite fossils from the Middle Cambrian (Drumian) of the Jince area. This set was collected during the years 1970–2015 by the first of the authors who focused on the scientifically interesting fossils that provide evidence about trilobite behaviour. The authors focused on comparing trilobite behavioural patterns describedin other locations or in earlier or later periods with the fossils in the set that was investigated. The first type of behavior investigated was the exuviation in Paradoxides gracilis that was described by Whittington (1990). A similar exuvial configuration was also documented in the samplesof Ellipsocephalus hoffi (Schlotheim, 1823) and of Conocoryphe sulzeri (Schlotheim, 1823). The second of the types of behavior investigated was mass exuviation. Our report on the findings also provided evidence of the occurrence of an identical fossil configuration in the Conocoryphe sulzeri species. The third of the types of behavior investigated was trilobite rolling that, until recently, had been disputed as being from the Cambrian. Nevertheless, the new findings (Esteve, 2013) state that the author detected significant variability of enrolment in the Cambrian trilobites. In our sample we found the following types of enrolment in the Czech Cambrian trilobites, in accordance with the Levi-Setti terminology (1993): incomplete, spheroidal, proper spiral enrolment, uncoiled spiral enrolment, basket and lid enrolment, in a total of seven trilobite species. Newly documented as a common behavioural pattern was the tucking of the pygidium in the otherwise stretched body of the three taxa of trilobites in the sample. The fourth of the types of behavior observed were the trilobite rows that were interpreted by Brett and Hunda (2011) as representing migration behaviour. I n our set this proved to be frequent in regard to Conocoryphe cirina (Šnajdr, 1982). The report on the findings demonstrates that some of the trilobite behavioural patterns familiar from other locations and periods can also be found in the trilobites from the Middle Cambrian of the Jince area.