Felidae Oligocene, about 25 million years ago, with the appearance of "Proailurus" and "Pseudaelurus". The latter species complex was ancestral to two main lines of felids, the cats in the extant subfamilies and a third major group of extinct cats, which are assigned to the subfamily Machairodontinae. The machairodonts included the saber-toothed cats such as the "Smilodon". The "false sabre toothed cats", the Barbourofelidae and Nimravidae, are not true cats, but are closely related and together with Felidae and other cat-like carnivores (hyaenas, viverrids and mongooses) make up the feliform carnivores. Results of mitochondrial analysis indicates that all the Felidae descended
Animals (Scientific Procedures) Act 1986 of regulation is governed by the granting of a "project licence" (PPL) to a suitably qualified senior researcher. The PPL details the scope of the work to be carried out, the likely benefits that may be realised by the work, and the costs involved in terms of the numbers and types of animals to be used, and the harm that might be caused to the animals. Typically a large and detailed document, the PPL precisely defines which techniques may be applied to particular animals and for what purpose. Finally, the 'place' where regulated procedures are carried out is controlled by