15th Swiss Geoscience Meeting, Davos 2017 Diversity of USA Radiodonta Stephen Pates*, Allison C. Daley** *Department of Zoology, University of Oxford, Oxford, OX2 6GG, United Kingdom ([email protected]) **Faculty of Geosciences and Environment, University of Lausanne, Sorge Géopolis, CH1015, Lausanne, Switzerland Our understanding of large Cambrian pelagic predators, including radiodontans such as Anomalocaris, Hurdia, Peytoia and Caryosyntrips has increased greatly over recent years (e.g. Daley et al. 2009). The bodyplan of a radiodontan includes a segmented frontal appendage specialised for feeding, a circular mouthpart made of radial plates, a segmented body with lateral flaps for movement, a pair of compound eyes, and an anterior sclerite. Recent work has identified radiodontans as stem group arthropods, and shed light on the origin of the biramous limb, the compound eye and arthropod brain structure (Paterson et al. 2011; Cong et al. 2014; Van Roy et al. 2015). Radiodontans are often preserved disarticulated: as isolated frontal appendages, mouthparts, or carapace elements. Frontal appendage morphology is often used to differentiate different species and genera, as well as to infer feeding style. Most recent studies have focussed on the Chengjiant Biota (China), Emu Bay Shale (Australia) and Burgess Shale (Canada). Radiodontans are also an important component of soft-bodied faunas from the Great Basin (Utah, Nevada, and California) and the Kinzers Formation (Pennsylvania). These deposits offer an opportunity to study the evolution and distribution of radiodontans at a local and regional level, and at high temporal resolution. These sites have also increased our knowledge of the diversity of Radiodonta. Amongst other radiodontans, three species of Anomalocaris, one species of Caryosyntrips, the youngest representative of Staneycaris and Tamisiocaris, and a new genus of hurdiid (Figure 1) are only known from USA deposits. Radiodontans from the USA show a trend that Anomalocarididae dominate in older sites, and Hurdiidae in younger sites. Interpretation of the functional morphology of these radiodontans suggests that these taxa possessed a range of ecologies, mirroring other, more famous, Cambrian Lagerstätten. !"#$%&'())%*+,)-(+.-+%/++#(.01%234,)%56!7% % % Q(0N@+%!>%UN@G((G%@3G(,G,.#3.%B@,A%#$+%&8+.-+%&$3<+%/+AV+@1%S3.0)#,.% Q,@A3#(,.1%D#3$%K=3AV@(3.%&+@(+)%d1%&#30+%"P>%S+B#]%=<,)+N8%,B%A,N#$83@#)%'(#$% #',%B@,.#3<%388+.G30+)%3.G%9`+<+A+.#)>%Y(0$#]%=,A8<+#+%)8+-(A+.1%)$,'(.0% +<,.03#+G%B<38)1%AN)-<+%V<,-O)1%A(G<(.+1%.+-O%B<38)%3.G%$+3G%@+0(,.>% % % YRQRYRa=R&%% =,.01%9>1%/31%H>1%U,N1%H>1%RG0+-,AV+1%*>%2>1%e%&#@3N)B+<G1%a>%f>%56![]%_@3(.% )#@N-#N@+%@+),<4+)%#$+%)+0A+.#3<%3BB(.(#?%,B%3.,A3<,-3@(G(G%388+.G30+)1%a3#N@+% "!d1%"dg>% 23<+?1%;>%=>1%_NGG1%*>%R>1%=3@,.1%f`_>1%RG0+-,AV+1%*>%2>1%e%=,<<(.)1%2>%566W]% X$+%_N@0+))%&$3<+%3.,A3<,-3@(G(G%UN@G(3%3.G%(#)%)(0.(B(-3.-+%B,@%+3@<?% +N3@#$@,8,G%+4,<N#(,.1%&-(+.-+1%d5d1!"W7`!I66>% 93#+@),.1%f>%Y>1%*3@-h3`_+<<(G,1%2>%=>1%S++1%/>%&>1%_@,-O1%*>%;>1%f30,1%f>%_>1%e% RG0+-,AV+1%*>%2>%56!!]%;-N#+%4()(,.%(.%#$+%0(3.#%=3AV@(3.%8@+G3#,@% !"#$%&#'%()*%3.G%#$+%,@(0(.%,B%-,A8,N.G%+?+)1%a3#N@+1%[g61%5d7`5[6>% \3.%Y,?1%9>1%23<+?1%;>%=>1%e%_@(00)1%2>%R>%56!"]%;.,A3<,-3@(G(G%#@N.O%<(AV% $,A,<,0?%@+4+3<+G%V?%3%0(3.#%B(<#+@`B++G+@%'(#$%83(@+G%B<38)1%a3#N@+1%"551%77>% %.