through the Triassic periods. The conodonts are thought to be bony
appendages of an unusual, soft-bodied animal resembling a hagfish. However,
the shape of the missing creature remained unclear until 1983, when paleon-
tologists discovered toothlike pieces at the forward end of an eel-shaped fos-
sil from Scotland. Furthermore, the presence of distinctive eye muscles in
conodonts not known in invertebrates pushed the vertebrate fossil record as
far back as the Cambrian.Conodonts show their greatest diversity during the
Devonian and are important for long-range rock correlations of that period.Figure 52Kimberella
was an odd-looking
Precambrian mollusk.
Figure 53Crustaceans
such as this crab are
primarily aquatic species.
Historical Geology