The Evae transgression: a major event?

The most extensive sea-level event of the Early Ordovician is known as the Evae transgression. During the highstand of this event, the conodont index species Oepikodus evae reached its acme and often coincided with the peak in conodont generic diversity. The main objective of this study is to statistically evaluate the degree of similarity in conodont species composition be -tween the Argentine Precordillera, Laurentia, Baltica, Kazakhstania, South China, and Australia at that time. Cluster analysis shows two main faunal groups moderately to poorly differentiated, indicating that some paleogeographic barriers may not have decreased during the Evae trans -gression. On the other hand, a paleolatitudinal control over the distribution of species is suspected, considering the occurrence of a higher number of species dwelling in mid-low lati - tudes than in mid-latitudes. This suggests that this event could have been of a lesser magnitude or duration than previously claimed.

Automated summary

The study aims to evaluate the similarity in conodont species composition between different regions during the Early Ordovician Evae transgression. Cluster analysis indicates the presence of two moderately to poorly differentiated faunal groups, suggesting that certain paleogeographic barriers may have remained during the transgression. There seems to be a paleolatitudinal control over species distribution, with a higher number of species dwelling in mid-low latitudes than mid-latitudes. This suggests a potentially smaller magnitude or duration for the Evae transgression.