Some recent non-Mesozoic birds papers in open access. (Some people have wanted more bird stuff...)
Estelle Bourdon, Anette V. Kristoffersen & Niels Bonde (2016)
A roller-like bird (Coracii) from the Early Eocene of Denmark.
Scientific Reports 6, Article number: 34050 (2016)
The fossil record of crown group birds (Neornithes) prior to the Cretaceous-Paleogene boundary is scarce and fragmentary. Early Cenozoic bird fossils are more abundant, but are typically disarticulated and/or flattened. Here we report the oldest roller (Coracii), Septencoracias morsensis gen. et sp. nov. (Primobucconidae), based on a new specimen from the Early Eocene (about 54 million years ago) Fur Formation of Denmark. The new fossil is a nearly complete, three-dimensionally preserved and articulated skeleton. It lies at the lower end of the size range for extant rollers. Salient diagnostic features of Septencoracias relative to other Coracii include the proportionally larger skull and the small, ovoid and dorsally positioned narial openings. Our discovery adds to the evidence that the Coracii had a widespread northern hemisphere distribution in the Eocene. Septencoracias is the oldest substantial record of the Picocoraciae and provides a reliable calibration point for molecular phylogenetic studies.
Alexander Suh (2016)
The phylogenomic forest of bird trees contains a hard polytomy at the root of Neoaves.
Zoologica Scripta 45(S1): 50–62
DOI: 10.1111/zsc.12213View/save citation
Birds have arguably been the most intensely studied animal group for their phylogenetic relationships. However, the recent advent of genome-scale phylogenomics has made the forest of bird phylogenies even more complex and confusing. Here, in this perspective piece, I show that most parts of the avian Tree of Life are now firmly established as reproducible phylogenetic hypotheses. This is to the exception of the deepest relationships among Neoaves. Using phylogenetic networks and simulations, I argue that the very onset of the super-rapid neoavian radiation is irresolvable because of eight near-simultaneous speciation events. Such a hard polytomy of nine taxa translates into 2 027 025 possible rooted bifurcating trees. Accordingly, recent genome-scale phylogenies show extremely complex conflicts in this (and only this) part of the avian Tree of Life. I predict that the upcoming years of avian phylogenomics will witness many more, highly conflicting tree topologies regarding the early neoavian polytomy. I further caution against bootstrapping in the era of genomics and suggest to instead use reproducibility (e.g. independent methods or data types) as support for phylogenetic hypotheses. The early neoavian polytomy coincides with the Cretaceous–Paleogene (K-Pg) mass extinction and is, to my knowledge, the first empirical example of a hard polytomy.
Beatrice Demarchi Shaun Hall Teresa Roncal-Herrero Colin L Freeman Jos Woolley Molly K Crisp Julie Wilson Anna Fotakis Roman Fischer Benedikt M Kessler Rosa Rakownikow Jersie-Christensen Jesper V Olsen James Haile Jessica Thomas Curtis W Marean John Parkington Samantha Presslee Julia Lee-Thorp Peter Ditchfield Jacqueline F Hamilton Martyn W Ward Chunting Michelle Wang Marvin D Shaw Terry Harrison Manuel Domínguez-Rodrigo Ross DE MacPhee Amandus Kwekason Michaela Ecker Liora Kolska Horwitz Michael Chazan Roland Kröger Jane Thomas-Oates John H Harding Enrico Cappellini Kirsty Penkman Matthew J Collins (2016)
A chemically unstable ostrich eggshell peptide survives for at least 3.8 million years at the equator, stabilized by strong mineral interactions.
Proteins persist longer in the fossil record than DNA, but the longevity, survival mechanisms and substrates remain contested. Here, we demonstrate the role of mineral binding in preserving the protein sequence in ostrich (Struthionidae) eggshell, including from the palaeontological sites of Laetoli (3.8 Ma) and Olduvai Gorge (1.3 Ma) in Tanzania. By tracking protein diagenesis back in time we find consistent patterns of preservation, demonstrating authenticity of the surviving sequences. Molecular dynamics simulations of struthiocalcin-1 and -2, the dominant proteins within the eggshell, reveal that distinct domains bind to the mineral surface. It is the domain with the strongest calculated binding energy to the calcite surface that is selectively preserved. Thermal age calculations demonstrate that the Laetoli and Olduvai peptides are 50 times older than any previously authenticated sequence (equivalent to ~16 Ma at a constant 10°C).