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