Seabirds as Ecological Indicators in Late Cretaceous Marine Environments

Laura E. Wilson, Fort Hays State University

Description

In modern marine ecosystems, seabirds are considered indicators of ecological hotspots because their biogeographic distribution is correlated with physical, chemical, and biological oceanographic factors. Pursuit diving seabirds – those that actively pursue prey underwater – are even more limited in distribution and closely tied to oceanographic factors, as diving ability is often gained at the expense of flight capabilities. Today, pursuit diving seabirds are generally restricted to waters cooler than 15ºC. By contrast, the Late Cretaceous was characterized by greenhouse climate and high sea levels that provided marine paleoenvironments with no modern analogs. Even though waters in the Western Interior Seaway (WIS) were warmer than 15ºC, they were host to pursuit diving seabirds called hesperornithiforms. The presence of hesperornithiforms in warm waters indicates that different biotic and abiotic factors affected Late Cretaceous epicontinental ecosystems than affect modern oceans. Together, ecosystem structure and the unique oceanographic factors characterizing epicontinental seas both contribute to differences in seabird biogeography between the Late Cretaceous and today.

 

Seabirds as Ecological Indicators in Late Cretaceous Marine Environments

In modern marine ecosystems, seabirds are considered indicators of ecological hotspots because their biogeographic distribution is correlated with physical, chemical, and biological oceanographic factors. Pursuit diving seabirds – those that actively pursue prey underwater – are even more limited in distribution and closely tied to oceanographic factors, as diving ability is often gained at the expense of flight capabilities. Today, pursuit diving seabirds are generally restricted to waters cooler than 15ºC. By contrast, the Late Cretaceous was characterized by greenhouse climate and high sea levels that provided marine paleoenvironments with no modern analogs. Even though waters in the Western Interior Seaway (WIS) were warmer than 15ºC, they were host to pursuit diving seabirds called hesperornithiforms. The presence of hesperornithiforms in warm waters indicates that different biotic and abiotic factors affected Late Cretaceous epicontinental ecosystems than affect modern oceans. Together, ecosystem structure and the unique oceanographic factors characterizing epicontinental seas both contribute to differences in seabird biogeography between the Late Cretaceous and today.