Named By: Samuel Wendell Williston - 1903.
Classification: Chordata, Reptilia, Sauropterygia, Plesiosauria, Pliosauridae.
Species: B. lucasi (type).
Size: Estimated around 10 meters long, Skull up to 1.7 meters long.
Known locations: USA, Kansas. Colombia.
Time period: Barremian through to the Turonian of the Cretaceous.
Fossil representation: Skulls, mandibles (lower jaws) as well as partial post cranial remains such as vertebrae.
represents one of the last of the large pliosaurs known to have swum in
the Mesozoic oceans. The heyday for the pliosaurs seems to have been
around the end of the Jurassic when others such as Pliosaurus
(the latter of which is thought to be one of the closest
relatives to Brachauchenius) were at their most
numerous. As the
Cretaceous continued however new competition in the form of mosasaurs
such as Tylosaurus
displaced the pliosaurs from their
position as the top predators of the oceans.
Like its predecessors Brachauchenius would have specialised in hunting large prey such as marine reptiles like plesiosaurs as well as possibly larger fish that would have been beyond the scope of smaller predators. Long associated with the Western Interior seaway (specifically Kansas) the discovery of Brachauchenius in Colombia, South America, proves that Brachauchenius was certainly not restricted to the United States. This is not all that surprising when you consider that a population of large predators like Brachauchenius cannot concentrate in one area otherwise they would exhaust the local supply of prey species. As such these predators have to spread out in order to maintain a balance between them and their prey so that their own species can survive.
Additionally the Colombian material not only extends the geographical range of Brachauchenius, but the temporal range as well. Further, Brachauchenius is one of the first of the large short necked pliosaurs to appear in the Cretaceous after an apparent disappearance between the end of the Jurassic and early-mid Cretaceous. Of course this does not mean to say that these pliosaurs disappeared completely just to reappear later, just that their remains are not as well documented.