For decades now, scientists have been on a constant search for finding clues about our planet’s vast, ancient past. While creatures of old like dinosaurs and mammoths have long played poster child to public awareness about these majestic animals and plants, there are countless other ancient animals out there that carry with them as much interest as their more-famous contemporaries.
Of particular interest for a certain study published in the journal Scientific Reports are insects that fall under the insect order Neuroptera. The order’s name is roughly Greek for “sinew wings,” given by the fact that their wings showcase extensive branching; these insects are also known as the net-winged insects.
These insects have been around for quite some time now, having first appeared in the fossil record in rocks dated to the end of the Permian Period some 250 million years ago. These insects have since evolved to scatter across the world, and are composed of several well-known members, including antlions, lacewings, and snakeflies.
The insects in this study, however, are so old that they’ve been identified from individuals trapped in 100-million-year-old amber, or fossilized tree resin. This particular study, which explored the odd features displayed by larvae trapped in amber and frozen in time, was spearheaded by Joachim Haug, zoologist from the Ludwig-Maximilians-Universität in Munich.
Of course, amber wouldn’t be the only place you’d look into when searching for fossilized insects; insects locked in time inside usual fossil rock are out there, much like the 49-million-year-old beetle fossil called “Attenborough’s Beauty.” This particular study, however, was rooted in findings from amber obtained in Myanmar’s Hukawng Valley.
What’s odd about these ancient larvae, however, is the fact that they seem so ornate. Features like giant mandibles, long antennae, limbs, and necks are all visible on these insects locked in time. The features seem reminiscent of predatory insects, but as they’ve been locked inside amber and are fossilized, scientists don’t know for certain what these features are really for.
“As in the case of all modern species of lacewings, these larvae were probably predators, but we know nothing about their prey,” said Haug in a statement.
They do know, however, that these features come as a stark contrast to what has been previously understood about these insects, wherein they undergo holometabolism once they reach a certain age in life—a process otherwise known as complete metamorphosis. The same phenomenon occurs in butterflies as they emerge from cocoons created by their previous caterpillar selves.
It has thus been assumed by some experts that these insect larvae don’t necessarily need standout features like giant jaws and long antennae while in their larval stage; after all, they’ll quite literally grow out of it in the end. To the scientists, larvae don’t really need these features until they reach adulthood, where they get a second chance through complete metamorphosis. And true enough, living Neuropterans like lacewings retain relatively “basic” larval forms, and only grow their standout features once they metamorphose into their adult forms.
Haug and team write in their paper: “The enormous evolutionary and ecological success of Holometabola has been attributed to the niche differentiation between the adult and the often highly aberrant-appearing larva. […] All these notions indirectly imply that holometabolan larvae are to a certain degree constrained in their possibilities to evolve morphologically diverse forms.”
To Haug and team, this feeling of surprise with their results really shows more of the scientific community’s “‘ignorance of larval forms’, and of how complex they can sometimes be,” writes news source ScienceAlert.
The eventual loss of these larval features in modern-day Neuropterans may play a role in why we understand so little about these larval forms, but the authors believe that “there is no principal constraint that hinders holometabolan larvae to develop such structures,” as they wrote on their paper.
Finally, the authors continued: “[These results] demonstrate, again, that considering only modern-day fauna will lead to the impression that certain morphological or developmental constraints exist, but which are in fact only artifacts due to ‘filtering history’.”
(For more insect finds, check out the potential ocean-spanning migrations taken by globe skimmer dragonflies.)
References
- Dockrill, P. (2021, November 1). “Extreme morphologies” in ancient insects show how little we know them at all. ScienceAlert. https://www.sciencealert.com/extreme-morphologies-in-ancient-insects-show-how-little-we-know-them-at-all
- Ent 425 | general entomology | resource library | compendium [neuroptera]. (n.d.). Retrieved November 4, 2021, from https://projects.ncsu.edu/cals/course/ent425/library/compendium/neuroptera.html
- Haug, J. T., Baranov, V., Müller, P., & Haug, C. (2021). New extreme morphologies as exemplified by 100 million-year-old lacewing larvae. Scientific Reports, 11(1), 20432. https://doi.org/10.1038/s41598-021-99480-w
- Holometabolous metamorphosis | biology. (n.d.). Encyclopedia Britannica. Retrieved November 4, 2021, from https://www.britannica.com/science/holometabolous-metamorphosis
- Ludwig-Maximilians-Universität Munich. (2021, October 28). Intriguing insect fossils preserved in amber. ScienceDaily. https://www.sciencedaily.com/releases/2021/10/211028143632.htm
