A new species of marsupial lion that lived approximately 18 million years ago has been identified from fossils found in Australia.
Reconstruction of Microleo attenboroughi. Image credit: Peter Schouten.
The new species, named Microleo attenboroughi, is described in the journal Palaeontologia Electronica, based on a partial skull and teeth.
Its dentition includes an elongate, knife-like premolar in front of basined molars – specialized features which are common to all members of the Thylacoleonidae, an extraordinary family of extinct marsupial carnivores from Australia, referred to as marsupial lions.
The fossilized remains of Microleo attenboroughi were found in the Riversleigh World Heritage Area, northwestern Queensland, and analyzed by experts from the University of New South Wales.
“The species name honors Sir David Attenborough for his dedication and enthusiasm in promoting the natural history of the world and the paleontological treasures of the Riversleigh World Heritage Area in particular,” the authors explained.
Microleo attenboroughi was much smaller than the other members of Thylacoleonidae, including its most famous relative – Thylacoleo carnifex.
“Microleo attenboroughi would have been more like the cute, but still feisty kitten of the family,” said lead author Dr. Anna Gillespie, of the PANGEA Research Centre at the University of New South Wales.
“It was not lion-size or even bob-cat-size. Weighing only about 600 grams, it was more like a ringtail possum in size.”
Microleo attenboroughi was recovered from a limestone deposit believed to have formed in a pool within a rainforest landscape about 19 million years ago, during the Miocene epoch.
The fossil deposit has already revealed a rich fauna including at least six different kinds of bandicoots, many kinds of possums and kangaroos, toothed platypuses, diminutive koalas, thousands of bats, fish, turtles, lizards, pythons and birds including storks, logrunners and the earliest-known Australian parrot.
“Despite its relatively small size compared with Thylacoleo carnifex, the new species was one of the larger flesh-eaters existing in its ancient community of rainforest creatures at Riversleigh,” said Prof. Mike Archer, also from the PANGEA Research Centre at the University of New South Wales.
“The diversity of marsupial lions alive at this time at Riversleigh is unmatched in the fossil record from anywhere else on the continent.”
“Microleo attenboroughi shared these northern Miocene rainforests with two larger species of marsupial lion, one cat-sized and the other dog-sized,” Dr. Gillespie added.
“Although it is possible they competed with one other, the size differences probably means they each specialized on a different size range of prey.”
“It’s likely that Microleo attenboroughi scampered amongst the tree-tops, gobbling insects as well as small vertebrates such as lizards and birds while simultaneously trying to avoid becoming a prey item for its larger relatives,” she said.
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Gillespie, Anna K. et al. 2016. A tiny new marsupial lion (Marsupialia, Thylacoleonidae) from the early Miocene of Australia. Palaeontologia Electronica 19.2.29A: 1-25
