29. Conodonts: Lower to Middle Ordovician Record

First part of the introduction

Conodonts, eel-shaped animals that were common inhabitants of Paleozoic and Triassic seas, are now interpreted to be chordates (Aldridge et al., 1993). Recent phylogenetic analyses based on morphological, biochemical, and physiological characters suggest conodonts to be the most plesiomorphic member of the group Gnathostomata (Donoghue et al., 2000). Their apatite feeding microelements are usually well preserved, and conodonts have a fossil record whose completeness competes with that of any other animal group (Foote and Sepkoski, 1999). The excellent fossil record of conodonts and their rapid evolution make them key tools for establishing high-resolution biostratigraphy from the Middle Cambrian through the Triassic.