Alexandronectes is a genus of elasmosaurid plesiosaur, a type of long-necked marine reptile, that lived in the oceans of Late Cretaceous New Zealand.

[1] A 2021 study used CT scans to create digital reconstructions of the holotype, and detected the stapes in the inner ear, marking the first time this bone has been found in an aristonectine.

The study also found a recess in the floccular lobe of the cerebellum, which may have functioned to stabilize both the head and the retinal image of Alexandronectes.

Fossils lied between rock of the Conway Formation, built of soft, erosive, but massive dark gray mudstones and mud sandstones with intensive marks of bioturbation and big spherical calcareous concretions from the end of Cretaceous,[4] from Maastrichtian.

Previously in the rocks of aforementioned formation fossils of Teleostei, shark teeth, brachiopods, plant remains and dinoflagellates had been found, the latter used to date another ones.

[1] The situation changed with publication of paper by Hiller and Mannering in 2004 in a journal published by Canterbury Museum, where the fossils had been transported to.

[4] Mentioned paper put the specimen in rich fauna of New Zealand late Cretaceous plesiosaurs, seven species of which had been described earlier, besides part of them becoming nomina dubia.

[1] In 2016 Otero, R. A., O'Gorman, J. P., Hiller, N., O'Keefe, F. R. & Fordyce, R. E. published in Journal of Vertebrate Paleontology a paper titled Alexandronectes zealandiensis gen. et sp.

Its specific epithet appeals to microcontinent of Zealandia, a land mass that broke away from supercontinent Gondwana in late Cretaceous epoch and contained areas of what is nowadays New Zealand.