The Ecomorph Concept in Conodont Biostratigraphy

1
The Ecomorph Concept in Conodont Biostratigraphy

• W. Britt Leatham
• CSU San Bernardino

2
Inferences of conodont paleoecology

• Paleosynecological associations
• Paleogeographic distribution
• Sedimentological interpretation

3
Inferences of conodont paleoecology

• Paleosynecological associations
• Paleogeographic distribution
• Sedimentological interpretation

4
Tools for Biological investigations

• Linnean taxa

5
Linnean species

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

6
Limiting factors on use of Linnean species

• Temporally restricted--evolution
• Spatially restricted--niche concept

7
Morphological essence

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

8
Morphological essence

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

9
Variation in basic elemental bauplan

• Within the apparatus--autecologic

10
Variation in basic bauplan

• Specific variation--evolutionary

11
Variation in basic bauplan

• Specific variation--paleobiogegraphy

12
Recurrent forms and apparatus types

• Iterative evolution of form

13
Recurrent forms and apparatus types

• Stability of symmetry transition series

14
Recurrent forms and apparatus types

• Minor, repetitive variation in long-term stable
  morphologies may indicate broad scale ecologic
  aptation.

15
Recurrent forms and apparatus types

• Variation of pectiniform elements indicates
  environmental sensitivity

16
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

17
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

18
Recurrent forms and apparatus types

• Antero-posterior elongation of elements

19
Recurrent forms and apparatus types

• Lateral growth on margins of cusp

20
Recurrent trends

• Increase in surface area through
  denticulation/serration

21
Element morphology
22
Recurrent forms and apparatus types

• Longevity of basic element types and apparatuses

23
Mass Extinctions

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

24
Heterochronic convergence
25
(No Transcript)