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 inquiry compared the Act to legislation from France, the U.S., and Japan. The report concluded that "virtually all witnesses agreed that the UK has the tightest system of regulation in the world" and that it is "the only country to require an explicit cost/benefit assessment of every application to conduct animal research." Note that costs are explicitly in terms of adverse effects on animals, not the financial cost to the experimenters. In 2005, Patricia Hewitt, then British Secretary of State for Trade and Industry, called the Act "[among] the strongest laws in the world to protect animals which are being