Figure 4. 1 , Arenosicaris inflata from the Furongian Elk Mound Group of Wisconsin – PRI–1013: 1a–c ( a at top, c at bottom), three phyllocarids; two partial, and one complete; 2 , Ceratiocaris acuminata , PE-664, inset image (YPM 212400) shows a telson with a row of small pits where

Figure 4 — Arenosicaris inflata n. gen. n. sp. from the Elk Mound Group (4.1–4.5, 4.7) and St. Lawrence Formation (4.6). 1 , PRI 10130 (holotype), a nearly complete phyllocarid, note prominent limb bases (arrowheads); 2 , PRI 10131a–c, three phyllocarids (a at top, c at bottom); two partial

Figure 5 —Camera lucida drawings of Arenosicaris inflata n. gen. n. sp. shown in Figure 4 ; in all camera lucida drawings where gray is present, gray represents areas of deep relief and white represents areas of high relief. 1 , PRI 10130 (holotype). This example illustrates abdominal

Figure 6 — Arenosicaris inflata n. gen. n. sp. carapaces from the Elk Mound Group. 1 , carapace internal mold, field specimen and 2 , (lucida). These specimens show the internal surface morphology of the carapace valves. Note the anterodorsal depression present in both examples, which may

Table 1 A number of morphological characters of representative Cambrian to Recent bivalved arthropods. Although the number of thoracic somites in Arenosicaris inflata is not presently known, a comparison of other features reveals its affinity with the Phyllocarida. Cells in gray represent

Figure 11 —Composite reconstructions of the arthropods presented in this study. 1 , Arenosicaris inflata n. sp. from the Elk Mound Group and Lodi Member, St. Lawrence Formation of Wisconsin. Reconstruction based on 47 specimens; 2 , Mosinieia macnaughtoni n. sp. from the Elk Mound Group

in A. At this level in the section, trace fossils occur in the channels, on the levees, and on the adjacent flats; body fossils occur only on the flats immediately adjacent to the levees. Pocket knife (arrowed) is 8.3 cm long. C) Body fossil of the phyllocarid Arenosicaris inflata from the Elk Mound Group

F igure 2 Elk Mound Group fossils, Blackberry Hill, Wisconsin, PRI Station 3421. 1 , PRI 11041, Protichnites eremita Form 2, Trackway E, (p = postabdominal imprint, s = segment, t = track); arrow indicates likely direction of travel; 2 , Arenosicaris inflata (phyllocarid crustacean), showing