by Carl Strang
Research on the Mesozoic Era has been a big focus of recent paleontological research, and much attention in particular has been paid to feathered dinosaurs and early birds. Chinese deposits, especially, have been productive. This week I share notes on selected studies in this area from last year’s literature.
W. Scott Persons, IV, Philip J. Currie, and Mark A. Norell. 2013. Oviraptorosaur tail forms and functions. Acta Palaeontologica Polonica, DOI: 10.4202/app.2012.0093 From a ScienceDaily article. Unusual (for dinosaurs) fused tail vertebrae and musculature, as well as preserved tail feathers in a flightless species, suggest that oviraptorosaurs (an herbivorous group of theropods) had an active tail-feather display, presumably used in courtship.
Xing, Lida, et al. 2013. Piscivory in the feathered dinosaur Microraptor. Evolution, DOI: 10.1111/evo.12119 From a ScienceDaily article. A fossil of the hawk-sized, 4-winged dromaeosaur Microraptor proves to have been capable of short controlled flights during which it could catch smaller birds and squirrel-sized tree dwelling mammals, and now fish. This was in early Cretaceous China.
Dyke, Gareth, et al. 2013. Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight. Nature Communications, DOI: 10.1038/ncomms3489 From a ScienceDaily article. They created a life-size model of Microraptor, one of the “5-winged” feathered dinosaurs (wing-like structures on the legs, and lift-capable tail) and tested it in a wind tunnel. It could glide efficiently for long distances with slow drop in altitude, but that depended most on lift from the arm-wings. That could have set the stage for further development of those wings leading to the powered flight of birds.
Zheng, Xiaoting, et al. 2013. Hind wings in basal birds and the evolution of leg feathers. Science 339:1309-1312. They looked at 11 bird fossils from the early Cretaceous and found, despite their belonging to different groups, that they had leg wings as in the feathered dinosaur Microraptor. The authors conclude that this feature was common to all the first birds.
O’Connor, J.K., et al. 2013. A new enantiornithine from the Yixian formation with the first recognized avian enamel specialization. Journal of Vertebrate Paleontology 33: 1-12. From a ScienceDaily article. The Enantiornithes were the most diverse birds of the Mesozoic, but died out for reasons that remain unknown (modern birds were another lineage). This study describes a newly found species (Sulcavis geeorum), from the early Cretaceous Chinese Liaoning deposits, which had teeth specialized with grooves on their back faces, thought to have facilitated feeding on invertebrates with hard exoskeletons. Dental diversity in the enantiornithines presumably reflects ecological diversity and accounts for the group’s success.
Chinsamy, Anusuya, et al. 2013. Gender identification of the Mesozoic bird Confuciusornis sanctus. Nature Communications 4: 1381 DOI: 10.1038/ncomms2377 As described in ScienceDaily. They found that fossils of this species lacking ornamental tail feathers possessed medullary bone, which is used by females to store minerals for eggshell formation. Their study also found that these early birds, unlike modern ones but like dinosaurs, began reproducing before reaching maturity.