Early Jurassic extinctions

Ichthyosaurus (derived from Greek () meaning 'fish' and () meaning 'lizard') is a genus of ichthyosaurs from the Early Jurassic (Hettangian - Pliensbachian) of Europe (Belgium, England, Germany and Portugal). Some specimens of the ichthyosaurid Protoichthyosaurus from England and Switzerland have been erroneously referred to this genus in the past. It is among the best known ichthyosaur genera, as it is the type genus of the order Ichthyosauria.

thumb|right|L. tenuirostris, Royal Ontario Museum thumb|right|Life restoration Leptonectes is a genus of ichthyosaur that lived in the Late Triassic to Early Jurassic (Rhaetian - Pliensbachian). Fossils have been found in Belgium, Germany, Spain and the United Kingdom. A possible specimen from Switzerland first reported in 2006, has been reclassified as that of Hauffiopteryx. The type species, L. tenuirostris, reached long, whereas L. moorei (NHMUK PV R 14370) likely reached long; the largest species, L. solei, was approximately long.

Oligokyphus ("few cusps") is an extinct genus of herbivorous tritylodontid cynodont known from the Late Triassic to Early Jurassic of Europe, Asia and North America.

Prosalirus is an extinct genus of primitive frog known from the Early Jurassic of North America. It contains a single species, P. bitis, known from the Kayenta Formation of Arizona.

Leptonectidae is a family of ichthyosaurs known from Late Triassic to Early Jurassic marine deposits in Europe. They were all small to medium-sized creatures, most noted for their very long, swordfish-like snouts, which could have been used like a weapon, slashing through schools of fish.

Clevosaurus (meaning "Gloucester lizard") is an extinct genus of rhynchocephalian reptile from the Late Triassic and the Early Jurassic periods. Species of Clevosaurus were widespread across Pangaea, and have been found on all continents except Australia and Antarctica. Five species of Clevosaurus have been found in ancient fissure fill deposits in south-west England and Wales, alongside other sphenodontians, early mammals and dinosaurs. In regards to its Pangaean distribution, C. hadroprodon is the oldest record of a sphenodontian from Gondwana, though its affinity to Clevosaurus has been que

Microcleididae is an extinct family of basal plesiosauroid plesiosaurs from the Early Jurassic (middle Sinemurian to late Toarcian stages) of France, Germany, Portugal and the United Kingdom. Currently, the oldest and the most known microcleidid is Eretmosaurus from the middle Sinemurian of the United Kingdom. Microcleididae was formally named and described by Roger B. J. Benson, Mark Evans and Patrick S. Druckenmiller in 2012.

Protoichthyosaurus is a genus of ichthyosaur from the early Jurassic of southern England and possibly Switzerland. Two species are known, P. prostaxalis—the type species, named by Appleby in 1979—and P. applebyi. A third species, P. prosostealis, was named by Appleby, but it was removed from the genus in 2017 due to its similarity to Ichthyosaurus. The genus Protoichthyosaurus was synonymized with Ichthyosaurus by Maisch and Hungerbuhler in 1997, and again by Maisch and Matzke in 2000. However, it was found to be distinct in 2017 by Dean Lomax and colleagues, who separated it from Ichthyosauru

Amaltheidae is a family of eoderoceratoidean ammonitids from the Lower Jurassic consisting of genera characterised by stigated discoidal oxycones—narrow involute shells with narrowly rounded to angular venters that bear a series of grooves, or ridges, along broad flanks, which according to the Treatise L, 1957, evolved into strongly ribbed planulates (discoidal evolute shells) with quadrate whorls, typically with crenulated keels; involving all together four genera.

thumb|right|The Triassic [[Saurichthys was a highly specialized predator]] thumb|right|Saurichthys|Costasaurichthys paucitrichus fossil thumb|right|Saurichthys|Saurichthys curionii fossil thumb|right|Fossil of the Jurassic saurichthyid Saurorhynchus brevirostris thumb|right|Morphological comparison of Saurichthyidae with extant needlefish and flying fish. A. Sinosaurichthys|Sinosaurichthys longipectoralis; B. Sinosaurichthys longimedialis; C. Sinosaurichthys minuta; D. Saurichthys dawaziensis from Middle Triassic of Dawazi Section, Luoping, Yunnan, China (based on Wu et al. 2009). E. Atlantic

Kuehneotheriidae is an extinct family of mammaliaforms traditionally placed within 'Symmetrodonta', though now generally considered more basal than true symmetrodonts. All members of Kuehneotheriidae which have been found so far are represented only by teeth, but these teeth have features which have led paleontologists to classify kuehneotheriids as very close relatives of the first true mammals. But fossil clades based solely on teeth often lead to difficulties (Ausktribosphenidae being a good example), and it is not possible to draw significant conclusions about mammalian evolution from Kueh

Hildoceratidae is a family of ammonoid cephalopods from the Lower Jurassic, lower Pliensbachian (Jamesoni zone) to lower Bajocian (maybe even upper Bajocian) substages, generally with strongly ribbed, involute shells. They are combined with the Hammatoceratidae (= Phymatoceratidae), Graphoceratidae, and Sonniniidae to make up the Hildoceratoidea.