Australia is home to a unique set of native land mammals, such as koalas, wombats, and wallabies. However, between 27 and 23 million years ago, the coastal seas of Australia were also inhabited by an assortment of whales unlike any others found today.
Among these strange creatures were mammalodontids, which would be equally iconic if they still existed. Recent discoveries from Victoria have revealed a diverse range of these unusual whales, with the latest find being a 25-million-year-old fossil of a newly named species, Janjucetus dullardi.
Janjucetus dullardi was unlike other whales, with short jaws lined with teeth and big eyes. Despite this, it was a baleen whale – but one that lacked the characteristic hair-like structures used for filtering plankton. The discovery provides insight into the evolutionary branch that led to modern toothless giants.
Fossil finds from Victoria’s Surf Coast have yielded three out of four named species of mammalodontids. Notable among these is Janjucetus hunderi, with a robust triangular snout and powerful jaw-closing muscles. In contrast, the newly discovered Janjucetus dullardi had different teeth and ear bones, warranting its classification as a separate species.
A tiny new whale
In 2019, school principal Ross Dullard found a fossil eroding out of rocks along the coast at Jan Juc in Victoria. The find was donated to Museums Victoria and meticulously cleaned for study. Analysis revealed that Janjucetus dullardi was approximately two metres long – the smallest fossil whale discovered in Australia.
The coastal waters off southern Australia were a warm-water paradise for these small, toothy whales during the Late Oligocene Warming era (26-23 million years ago). The region’s unique combination of geography and climate allowed mammalodontids to thrive. Unfortunately, their habitat disappeared due to global cooling around 23 million years ago.
The discovery of Janjucetus dullardi sheds light on the origins of mammalodontids, which likely evolved up to 34 million years ago in isolation off southern Australia. Further research is needed to unravel the mysteries surrounding these unusual whales and their place in baleen whale evolution.
Source: https://theconversation.com/a-cornucopia-of-tiny-bizarre-whales-used-to-live-in-australian-waters-heres-one-of-them-262806