The Ecomorph Concept in Conodont Biostratigraphy W Britt

The Ecomorph Concept in Conodont Biostratigraphy W. Britt Leatham CSU San Bernardino

Inferences of conodont paleoecology • Paleosynecological associations • Paleogeographic distribution • Sedimentological interpretation

Tools for Biological investigations • Linnean taxa

Linnean species • Temporally restricted • evolution • Environmentally restricted • One niche--one species

Limiting factors on use of Linnean species • Temporally restricted--evolution • Spatially restricted--niche concept

Morphological essence • Basic morphological pattern in conodont elements is a draped basal cavity (cusp)

Variation in basic elemental bauplan • Within the apparatus--autecologic

Variation in basic bauplan • Specific variation--evolutionary

Variation in basic bauplan • Specific variation--paleobiogegraphy

Recurrent forms and apparatus types • Iterative evolution of form

Recurrent forms and apparatus types • Stability of symmetry transition series

Recurrent forms and apparatus types • Minor, repetitive variation in long-term stable morphologies may indicate broad scale ecologic aptation.

Recurrent forms and apparatus types • Variation of pectiniform elements indicates environmental sensitivity

Recurrent forms and apparatus types • Ligonodiniform Sc elements typify post. Ordovician ramiform elements of the symmetry transition series • Pre-Silurian conodont faunas include coniform-dominated apparatuses

Recurrent forms and apparatus types • Antero-posterior elongation of elements

Recurrent forms and apparatus types • Lateral growth on margins of cusp

Recurrent trends • Increase in surface area through denticulation/serration

Element morphology

Recurrent forms and apparatus types • Longevity of basic element types and apparatuses

Mass Extinctions • Changes in linnean taxonomic composition- exploitation of ecospace? • Quantifiable change--e. g. Aldridge

Heterochronic convergence