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Palaeontology is the study of prehistoric species, mostly ones that are extinct. It focuses primarily on fossil data, using a variety of physical, chemical and biological techniques to analyse them.
Atmospheric carbon dioxide concentrations remained below 840 parts per million and polar regions were glaciated throughout much of the Early Cretaceous except during episodic volcanism, according to an analysis of stable isotope composition of plants and biogenic carbonate data.
Ancient proteins carry genetic information from fossils that are too old or degraded for ancient DNA recovery. This protocol describes the extraction and tandem mass spectrometry sequencing of million-year-old dental enamel proteins for phylogenetic inference.
For a century, scientists pondered whether bird flight evolved by animals gliding down from trees or by creatures running and flapping from the ground up. A landmark 1974 paper reset the debate to focus on the evolution of the flight stroke instead.