Named By: Louis Dollo - 1885.
Classification: Chordata, Reptilia, Squamata, Mosasauridae, Tylosaurinae.
Species: H. bernardi (type).
Size: Estimated Between 12 and 15 meters long.
Known locations: Europe.
Time period: Campanian to Maastrichtian of the Cretaceous.
Fossil representation: Many specimens but of partial remains.
is usually considered to be one of the largest known mosasaurs;
however its actual size is a subject of on-going study. Early length
estimates placed Hainosaurus at seventeen meters,
while later study
towards the end of the twentieth century revised this down to
fifteen. A Hainosaurus specimen from Sweden that
was described by
Johan Lindgran has seen the total length of Hainosaurus
fall to just
over 12 meters. As is always the case an exceptionally well
preserved specimen of a fully grown adult would be required to settle
the size of Hainosaurus without question.
Even at a more modest twelve meters, Hainosaurus was still one of the bigger predators in the late Cretaceous seas, with only very rare larger predators like Mosasaurus being able to challenge its dominance. Hainosaurus was probably a generalist predator of other large marine organisms such as turtles, smaller mosasaurs, later plesiosaurs, as well as possibly large fish and sharks. While still growing up however it may have included other types of smaller animals such as ammonites and even birds, as indicated by fossil evidence for other mosasaurs.
As a tylosaurine mosasaur Hainosaurus is thought to have been most closely related to other mosasaurs such as Tylosaurus and Taniwhasaurus.