New revelations in three fossil species of ancient Tasmanian tiger ancestors found at Riversleigh World Heritage Area offer fresh insight into the ancestry and evolution of this now exctinct iconic marsupial predator.
Meet the Thylacines’ First Cousins
Paleontologists from UNSW Sydney have discovered rare fossils of 3 new species of marsupial lions that existed for millions of years before the last known extant Tasmanian Tiger.
The largest of these ancestors, also new and also living well into the much later Quaternary, was the 7-11-kilogram Badjcinus timfaulkneri, similar in size to a large Tasmanian devil. This fierce beast, named for the director of the Australian Reptile Park Tim Faulkner, stands as the earliest yet recorded member of the thylacine lineage and dates to back to 25-23 million years ago in Late Oligocene times.
The find of Badjcinus timfaulkneri, along with two other new species, Nimbacinus peterbridgei and Ngamalacinus nigelmarveni gives key insights into the evolutionary path of the Tasmanian tiger. Such fossils provide new insights to the diversification and adaptive remarkableness of this marsupial carnivore lineage, offering a more complete scope on the ancestral roots and diversity of an extinct megafauna member within its former ecosystem.
Ancestry of the Tasmanian Tiger
Published in the Journal of Vertebrate Paleontology, the research shows that this new thylacine species had highly specialized teeth, indicating the presence of distinct carnivorous niches within the high diversity fauna of ancient rainforests in Riversleigh.
One such animal is Nimbacinus peterbridgei, which had been named after the geologist and paleontology supporter Peter Bridge, was a little larger than the Tiger Quoll and would have hunted small mammals (and possibly some other prey species). All of them are thought to be potential direct ancestors of the larger, more powerful Nimbacinus dicksoni that lived 15 million years ago.
The third thylacine-like deposit [Ngamalacinus nigelmarveni] was at least an almost complete skull with associated jaws, also belonging to a relatively large enigmatic animal which I reconstruct as highly carnivorous from the elongate cutting blades and deeply meat-slicing notches on its lower molars. Named after wildlife documentary maker Nigel Marven, the species weighed in at just over 5.1kg, comparable to a red fox.
The coexistence of these three specialized thylacine lineages in the late Oligocene testifies to an immediate diversification and adaptation of this marsupial group following its first appearance in the fossil record. This study also removes the idea that Australia was smothered by reptilian meat-eaters across this time, presenting a mammalian carnivore variety at Riversleigh that matches any other environment on earth.
Conclusion
The finding of the three early thylacine ancestors illuminates not just the evolutionary past of the iconic Tasmanian tiger, but also one angle on the impressive mammalian diversity that inhabited ancient Australia’s forests. As we uncover more and more of the past, these new discoveries threaten to rearrange our understanding of where in nature the Tasmanian tiger belonged over the immense web of life that one roamed this most magnificent region.
