Leptocleididae

{{Automatic taxobox

| fossil_range = Early Cretaceous, {{fossilrange|Berriasian|Albian}}

| image = Leptocleidus_BW.jpg

| image_upright = 1.15

| image_caption = Leptocleidus

| taxon = Leptocleididae

| authority = White, 1940

| subdivision_ranks = Genera

| subdivision =

{{extinct}}Brancasaurus
{{extinct}}Hastanectes
{{extinct}}Leptocleidus
{{extinct}}Nichollssaura
{{extinct}}Umoonasaurus
{{extinct}}Vectocleidus

}}

Leptocleididae is a family of small-sized plesiosaurs that lived during the Early Cretaceous period (early Berriasian to early Albian stage). They had small bodies with small heads and short necks. Leptocleidus and Umoonasaurus had round bodies and triangle-shaped heads. Leptocleidids have been found in what were shallow nearshore, freshwater and brackish habitats.{{cite journal |last1=Bunker |first1=Georgina |last2=Martill |first2=David M. |last3=Smith |first3=Roy E. |last4=Zouhri |first4=Samir |last5=Longrich |first5=Nick |title=Plesiosaurs from the fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and a review of non-marine plesiosaurs |journal=Cretaceous Research |date=1 December 2022 |volume=140 |pages=105310 |doi=10.1016/j.cretres.2022.105310 |bibcode=2022CrRes.14005310B |s2cid=250964381 }} Hilary F. Ketchum and Roger B. J. Benson (2010), transferred Brancasaurus, Kaiwhekea, Nichollssaura and Thililua to this family.{{Cite journal|author1=Ketchum, H. F. |author2=Benson, R. B. J. |year=2010 |title=Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses |journal=Biological Reviews |volume=85 |issue=2 |pages=361–392 |doi=10.1111/j.1469-185X.2009.00107.x |pmid=20002391|s2cid=12193439 }} However, Ketchum and Benson (2011) reassigned Kaiwhekea and Thililua to their original positions, as an elasmosaurid and a polycotylid, respectively.{{cite journal |last1=Ketchum |first1=Hilary F. |last2=Benson |first2=R. B. J. |title=A new pliosaurid (Sauropterygia, Plesiosauria) from the Oxford Clay Formation (Middle Jurassic, Callovian) of England: evidence for a gracile, longirostrine grade of Early-Middle Jurassic pliosaurids |journal=Special Papers in Palaeontology |date=2011 |volume=86 |pages=109–129 |url=https://eprints.esc.cam.ac.uk/2336/ }}