This 2010 video from the USA is about the Eocene.
From Naturwissenschaften journal in Germany:
These structures, which are unknown from extant birds and other vertebrates, were previously described for an avian skeleton from Messel but considered a singular feature of this specimen.
The new fossils are from a different species of uncertain phylogenetic affinities and show that tuberculated vertebrae have a wider taxonomic, temporal, and geographic distribution.
In contrast to previous assumptions, they are no ontogenetic feature and arise from the vertebral surface.
It is concluded that they are most likely of pathologic origin and the first record of a Paleogene avian disease.
Their regular and symmetrical arrangement over most of the external vertebral surface indicates a systemic disorder caused by factors that do not affect extant birds, such as especially high-dosed phytohormones or extinct pathogens.
Dasornis, gigantic toothed Eocene birds: here.
British Eocene birds: here.
- UNESCO World Heritage Site #214: Messel Pit Fossil Site (everything-everywhere.com)
- Ancestor of humming bird and swift (earthtimes.org)
- Bird fossil sheds light on how swift and hummingbird flight came to be (eurekalert.org)
- Another link between CO2 and mass extinctions of species (arctic-news.blogspot.com)
- Dinosaur age bird discovery (dearkitty1.wordpress.com)
- The Eocene to Oligocene transition in Australia (phdland.com)