Middle Jurassic first appearances

The Galatheoidea are a superfamily of decapod crustaceans comprising the porcelain crabs and some squat lobsters. Squat lobsters within the three families of the superfamily Chirostyloidea are not closely related to the squat lobsters within the Galatheoidea. The fossil record of the superfamily extends back to the Middle Jurassic genus Palaeomunidopsis.

thumb|Life restoration of members of the Metriorhynchinae compared to a human Metriorhynchidae is an extinct family of specialized, aquatic metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period (Bajocian to early Aptian) of Europe, North America and South America. The name Metriorhynchidae was coined by the Austrian zoologist Leopold Fitzinger in 1843. The group contains two subfamilies, the Metriorhynchinae and the Geosaurinae. They represent the most marine adapted of all archosaurs.

thumb|Pholidosaurus|Pholidosaurus purbeckensis fossil.

Triconodontidae is an extinct family of small, carnivorous mammals belonging to the order Eutriconodonta, living in what would become Asia, Europe, North America and probably also Africa and South America during the Jurassic through Cretaceous periods at least from 190–66 mya.

Gobiconodontidae is a family of extinct mammals that ranged from the mid-Jurassic to the early Late Cretaceous, though most common during the Early Cretaceous. The Gobiconodontids form a diverse lineage of carnivorous non-therian mammals, and include some of the best preserved Mesozoic mammal specimens.

Shuotheriidae is a small family of Jurassic mammaliaforms whose remains are found in China, Great Britain and possibly Russia. They have been proposed to be close relatives of Australosphenida (which often controversially includes monotremes), together forming the clade Yinotheria. However, some studies suggest shuotheres are closer to therians than to monotremes, or that australosphenidans and therians are more closely related to each other than either are to shuotheres, with a 2024 study suggesting that shuotheriids were closely related to Docodonta outside of the Mammalia crown group.

Kalligrammatidae, sometimes known as kalligrammatids or kalligrammatid lacewings, is a family of extinct insects in the order Neuroptera (lacewings) that contains twenty genera and a number of species. The family lived from the Middle Jurassic to the early Late Cretaceous before going extinct. Species of the family are known from Europe, Asia, and South America. The family has been occasionally described as "butterflies of the Jurassic" based on their resemblance to modern butterflies in morphology and ecological niche.

Amphitheriidae is a family of Mesozoic mammals restricted to the Middle Jurassic of Britain, with indeterminate members also possibly known from the equivalently aged Itat Formation in Siberia and the Anoual Formation of Morocco. They were members of Cladotheria, more derived than members of Dryolestida, and possibly forming a close relationship with Peramuridae. Amphitheriidae is the only family of the order Amphitheriida.

The Cymatoceratidae is a family of Mesozoic and early Cenozoic nautiloid cephalopods and the most abundant of their kind in the Cretaceous. They are characterized by ribbed, generally involute shells of varied forms - coiled such that the outer whorl envelops the previous one, as with Nautilus, and sutures that are variably sinuous.

Aspidorhynchidae (from Ancient Greek ἀσπίς (aspís), meaning "shield", and ῥύγχος (rhúnkos), meaning "snout") is an extinct family of ray-finned fish from the Mesozoic Era. It is the only member of the monotypic order Aspidorhynchiformes. Members of the group are noted for their elongated, conical rostrums, of varying length, formed from fused premaxillae. The range of the group extends from the Middle Jurassic to the end of the Maastrichtian, with a potential record from the Late Paleocene. The family and order were described by Pieter Bleeker in 1859.