Paleontologists gained groundbreaking new perspectives on the evolution of kangaroos. They did this by focusing their efforts on an old insect species – Dorcopsoides fossilis. This large kangaroo lived more than 7 million years ago during the Late Miocene epoch. As such, it provides essential data on how these early macropodines responded to the dynamic environments developing across much of Australia. Dorcopsoides fossilis is only known from the Alcoota rich fossil field in southern Northern Territory. Based on its teeth, this extraordinary species is thought to be one of the oldest “modern” kangaroos, a distant cousin to modern kangaroos and wallabies.
Dr. Isaac Kerr from the Paleontology Lab at Flinders University, who led the study that identified these striking features of Dorcopsoides fossilis. Their robust hind limb bones show modifications more consistent with adaptations to saltatory locomotion (hopping) across open, dry grassland environments. This discovery offers the first direct proof of adaptations in kangaroos from this period. It further illuminates how they transformed over time as the climate warmed.
Insights from Fossil Analysis
Dr. Kerr and his team performed a thorough comparison of the limb bones of Dorcopsoides fossilis with other taxa. So they furthered their research by comparing these bones to those of living species. This extensive study provided the opportunity for researchers to dive deeper into kangaroo evolution than ever before.
“For the first time we have analyzed all their fossilized limb bones and compared them with limbs of living (extant) species, to shed light on kangaroo evolution.” – Dr. Isaac Kerr
The comparison between Dorcopsoides fossilis and extant gray kangaroos showed that they had certain morphological characteristics in common. This indicates that it was capable of very efficient long-distance hopping. This ant species has really strong legs that allow it to use its unique adaptations. These adaptations allowed it to survive the great Australian drying, as the continent morphed from wet rainforests to dry eucalypt woodlands between 11 and 7 million years ago.
Dr. Kerr noted, “During this period, macropodines became a dominant feature of the Australian landscape, which they still are today. Until this study of Dorcopsoides fossilis, we have had almost no fossil evidence of the evolution of their iconic hindlimbs during this period.”
Evolutionary Context
Dorcopsoides fossilis belongs to the forest-wallaby group, or tribe Dorcopsini. Among those relatives are the ancestors that grazed the Australian mainland until around 5 million years ago. The research shows Dorcopsoides fossilis to be a species of ecological interest. This animal probably looked like an oversized forest wallaby with proportionately longer legs, allowing it to adapt more efficiently to its respective environment.
“Living forest wallabies are peculiar, with slightly sad, whippet-like faces. Their strong, curved tails arch during slow movement so only the very tip touches the ground. Dorcopsoides fossilis may have looked like a larger, longer-legged version.” – Dr. Isaac Kerr
This macroevolutionary lens offers a broader and perhaps deeper understanding of Dorcopsoides fossilis. Equally, it shows her connection to the great family tree of kangaroos and wallabies.
The Significance of Research
Dorcopsoides fossilis was originally described in 1967 from partial jaws, teeth, and metatarsals. Since then, it’s received almost no attention. A new paper from this year featured in Royal Society Open Science addresses this gap directly. Co-authored by Professor Gavin Prideaux, it stresses the essential role of fossil evidence in uncovering the real story of how macropodines evolved.
“It bolsters evidence from more recent fossils and from genetic analyses about the timing and nature of the rise of macropodines.” – Professor Gavin Prideaux
This study addresses critical gaps in the fossil record. It enriches our understanding of how these animals adapted to their environments during a pivotal period in Australia’s geological history.