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 and replaced by EU Directive 2010/63/EU In 2002, a Government select committee inquiry described the Act as the "...tightest system of regulation in the world" in relation to the regulation of using animals for research. Prior to ASPA, the use of animals in the UK was regulated by the Cruelty to Animals Act 1876, which enforced a licensing and inspection system for vivisection. Animal cruelty was previously regulated by the Protection of Animals Act 1911 (now largely repealed) and more recently by the Animal Welfare Act 2006, both of which outlaw the causing of "unnecessary suffering". Specific exemptions apply to