The beetles were so involved with cycads that they evolved special adaptations like mandibular patches that transport pollen. Indeed, when Cai and colleagues examined the fossil more closely under a microscope, they discovered tiny pollen grains. Liqin Li, an expert in ancient pollen at the Chinese Academy of Sciences, later confirmed that the pollen grains belonged to a cycad.
A phylogenetic analysis explored the beetle’s family tree, showing that the insect belonged to a sister group to the extant (still surviving) Australian Paracucujus, which pollinate the relic cycad Macrozamia riedlei.
Illustration of Cretoparacucujus burmiticus pollinating a gymnosperm. Credit: Chenyang Cai.
Bearing in mind the current distribution of related beetle-herbivore and cycad-host pairs in South America and Australia, the findings suggest that cycad pollination has an ancient origin. How old? Likely before the breakup of the Gondwana supercontinent during the Early Jurassic, some 167 million years ago, Cai says. But this is an unproven hypothesis at this stage — for instance, scientists will need to find fossilized cycad leaves from this period.
The findings appeared in the journal Current Biology.
