Paradoxides signature taxon of the Avalonian Faunal Province

Paradoxides (signature taxon of the Avalonian Faunal Province) Avalonia – A dismembered Cambrian continent

Jurassic Period (180 Ma)

Jaccard Index (M/M+N) Most similar: W and St Least similar: So and BC Dice Index 2 M/(2 M+N) Most similar: W and St Least similar: So and BC

Raup-Crick Index Most similar: St and So Least similar: W and BC (So different indices yield different results – they are not statistical tests) Simpson Index Most similar: 4 tied at 1. 00 (Sensitivity Issues) Least similar: So and BC

Jaccard & Dice Indices W and St are most similar H 0 = W and St in close proximity? (Perhaps, but lifestyle? ) According to three of the four Indices So and BC are least similar H 0 = So and BC widely separated? (Whoa! When was the Sonoman Orogeny? Maybe latitude and/or a mountain chain are more plausible. )

Taylor (2006)

Base of the Ptychaspid Biomere

Taylor (2006)

Lower Ordovician Trilobite Faunas (Loch, 2007)

Lower Ordovician (Upper Ibexian) trilobite faunas Jaccard Index values for species data from nine locations in Laurentian North America

Factors affecting the index: 1. Taxonomy: lower grade, lower values; accuracy? 2. Relative Sample Size (AL/MT vs. UT; TX vs. OK) 3. Stratigraphic precision/accuracy (same age? ) 4. Real differences in composition (environment)

Utility of fossils for establishing and testing hypotheses For establishing: Ho = Sonomia had not yet docked by Pliensbachian Age (based on minimal similarity of So and BC in Jaccard & Dice Indices) For testing: Ho = Precordillera Terrane in Argentina is Perigondwanan (not Laurentian)

Origin of the Argentine Precordillera: Laurentian vs. Peri-Gondwanan

Clelandia texana Clelandia parabola

Plethopeltis stitti

Plethopeltis new species

Chapmania taylori

Heymonsicambria taylori

Chapmania taylori

“Plethopeltis lochi”