The Ecomorph Concept in Conodont Biostratigraphy

W. Britt Leatham

CSU San Bernardino

Inferences of conodont paleoecology

• Paleosynecological associations

• Paleogeographic distribution

• Sedimentological interpretation

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)

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

• 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