|a hypothetical surviving bird lineage -- small-bodied and specialized for a ground-dwelling lifestyle -- fleeing a burning forest in the aftermath of the asteroid strike that eliminated non-avian dinosaurs and destroyed global forests.|
in Field, Bercovici, Berv, et al., 2018.
Illustration: Phillip M. Krzeminski
• The end-Cretaceous mass extinction devastated forest habitats globally
• Tree-dwelling birds failed to persist across the end-Cretaceous extinction event
• All bird groups that survived the end-Cretaceous extinction were non-arboreal
• The early ancestors of many modern tree-dwelling bird groups were ground-dwelling
The fossil record and recent molecular phylogenies support an extraordinary early-Cenozoic radiation of crown birds (Neornithes) after the Cretaceous-Paleogene (K-Pg) mass extinction. However, questions remain regarding the mechanisms underlying the survival of the deepest lineages within crown birds across the K-Pg boundary, particularly since this global catastrophe eliminated even the closest stem-group relatives of Neornithes. Here, ancestral state reconstructions of neornithine ecology reveal a strong bias toward taxa exhibiting predominantly non-arboreal lifestyles across the K-Pg, with multiple convergent transitions toward predominantly arboreal ecologies later in the Paleocene and Eocene. By contrast, ecomorphological inferences indicate predominantly arboreal lifestyles among enantiornithines, the most diverse and widespread Mesozoic avialans. Global paleobotanical and palynological data show that the K-Pg Chicxulub impact triggered widespread destruction of forests. We suggest that ecological filtering due to the temporary loss of significant plant cover across the K-Pg boundary selected against any flying dinosaurs (Avialae) committed to arboreal ecologies, resulting in a predominantly non-arboreal post-extinction neornithine avifauna composed of total-clade Palaeognathae, Galloanserae, and terrestrial total-clade Neoaves that rapidly diversified into the broad range of avian ecologies familiar today. The explanation proposed here provides a unifying hypothesis for the K-Pg-associated mass extinction of arboreal stem birds, as well as for the post-K-Pg radiation of arboreal crown birds. It also provides a baseline hypothesis to be further refined pending the discovery of additional neornithine fossils from the Latest Cretaceous and earliest Paleogene.
Daniel J. Field, Antoine Bercovici, Jacob S. Berv, Regan Dunn, David E. Fastovsky, Tyler R. Lyson, Vivi Vajda and Jacques A. Gauthier. 2018. Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction. Current Biology. In Press. DOI: 10.1016/j.cub.2018.04.062
What the asteroid that wiped out dinosaurs meant for birds eurekalert.org/e/8gbw via @CellPressNews @EurekAlert
When the dinosaurs died, so did forests—and tree-dwelling birds phys.org/news/2018-05-dinosaurs-died-forestsand-tree-dwelling-birds.html via @physorg_com