conodonts

Conodonts are an extinct lineage of primitive jawless chordates known primarily from their conodont elements, small tooth-like fossils that formed part of a feeding apparatus. The elements, ranging from microscopic to a few millimeters in length, are made of apatite (calcium phosphate) and are among the most durable microfossils in the marine fossil record. Because soft-bodied remains are rarely preserved, the full appearance and biology of conodonts are inferred largely from their mineralized elements.

The conodont apparatus consists of multiple elements arranged in a feeding unit, with the shapes and arrangements varying across taxa. The elements are interpreted as components of a complex mechanism used to grasp, filter, or process prey, though exact function and mechanics are still subjects of study. Conodonts inhabited marine environments and spanned a wide range of ecological settings, from open-ocean to coastal environments, during various Paleozoic and early Mesozoic eras.

Temporal range and significance in dating: Conodonts first appear in the Early Cambrian and persist until the end of the Triassic, roughly 520 to 199 million years ago, with a peak in diversity during the Paleozoic. Their rapid evolution and wide geographic distribution make them exceptionally useful for biostratigraphy; conodont species and assemblages define many Paleozoic stages and subintervals, enabling detailed correlation of marine rocks worldwide.

Taxonomy and interpretation: Conodonts comprise an extinct clade within the early vertebrate lineage. While long debated, they are generally regarded as vertebrate or near-vertebrate chordates, and their mineralized elements provide some of the earliest evidence of skeletal tissue in this lineage. Ongoing research continues to refine their evolutionary relationships and the biology of the animals that produced these iconic elements.