细齿兽超科（Miacoidea），又名古裂脚兽，是已灭绝的侧系群总科，传统上分为两类，包括细齿兽科及古灵猫科。牠们是原始的肉食性动物，生存于3300-6500万年前古新世及始新世。细齿兽超科是一个包括一些细齿兽类的侧系群，仅在食肉目以外。故此，细齿兽超科是食肉形类顶部群的组合。食肉形类包括了细齿兽超科及食肉目，但不包括肉齿目。细齿兽超科被认为是食肉形类的基底。

由细齿兽超科至细齿兽科与犬型亚目，及古灵猫科至猫型亚目的演化是古新世及始新世末期的趋势，在北美洲及欧亚大陆都有出现。支序分类学分析显示不同的细齿兽超科演化成不同的食肉目分支。古灵猫科与猫型亚目都是只有两颗臼齿及较长的头颅骨。而细齿兽类要直至古新世最末期才出现，并有较短的头颅骨，而跟骨与腓骨没有接触。根据化石纪录，这两类都可以追溯至古新世早期。细齿兽科演化成现今的犬型亚目（即狗、熊、浣熊及鼬），而古灵猫科则演化成猫型亚目（即猫、鬣狗及猫鼬）。

Miacoidea is a paraphyletic superfamily that had been traditionally divided into two families of carnivores: Miacidae (the miacids) and Viverravidae. Miacoids were primitive carnivores that lived during the Paleocene and Eocene Epochs, about 33-66 million years ago. Today, Miacidae is recognized as a paraphyletic array of stem taxa that probably resulted in some "miacid" genera ending up just outside the order Carnivora, the crown-group within the Carnivoramorpha. Carnivoramorpha consists of both Miacoidea and Carnivora, but excludes the order Creodonta that existed alongside Carnivoramorpha. Miacoids are regarded as basal carnivoramorphs. The miacids are a paraphyletic group containing all miacoids that are not viverravids.