Insects and their fellow creepy crawlies have been around for a long, long, looong time. Long before dinosaurs ever showed up on stage. A common misconception is that creepy crawlies in prehistoric times were limited to just dragonflies, millipedes, and perhaps spiders, and they were all giant. I’m thinking about a certain eagle-size dragonfly and six-foot long millipede in particular. But there was only one period of history that insects and their other arthropod relatives (like spiders) were truly giant- the Carboniferous period. The Permian Period- the Age of Amphibians- is the span of time between the Carboniferous and Triassic period. The Triassic Period, of course, is when the first dinosaurs came on the scene.
The reason for the giant size of creepy-crawlies during the Carboniferous, and no other period, where the high levels of oxygen from the boom in forest and tree growth around the world. By the time the Jurassic Period rolls around, oxygen levels are a bit more like they are today, and bugs are about as big as they get today. The “bugs” in this series are only a tiny fraction of the diversity there was during the Jurassic. They are delicate creatures and do not fossilize easily, so who knows how many there really were? Most of these still have surviving species today that look very similar to how they looked so many years ago, and they provide a tiny glimpse to the many strange and wonderful insects that flew in the air and crawled in the leaf litter during the Jurassic.
For part one of this series I’ll explore beetles. The oldest known fossil insect that looks more like modern beetles is from the Permian Period, about 270 million years ago. At that time beetles were mostly limited to a few fungus and algae-feeding species, including a few that started to look a little like the weevils and rove beetles below. It wasn’t until the Jurassic period that beetles really started to diversify into the shapes we recognize today. Below are a few of the basic groups we could observe if we went back in time to the Jurassic Period.
Any sort of list for prehistoric insects was mostly unhelpful. Research for this series mostly involved painstaking unwinding of threads from modern groups, then tracing back on which ones are the oldest and most “primitive” groups. Luckily, Wikipedia has a handy little chart on the upper right-hand corner for almost every insect genus and family that says when in time it appeared. I would then trace those lineages and see if I could find fossil versions, or modern species that look nearly identical to their fossil ancestors.
Once I crawled into the rabbit hole I just had to keep going, even when I realized I’d bitten into quite a bit more than I could chew! I hope you enjoyed it as much as I did! 😀
I am eternally grateful that Wikipedia is such a great resource. From the sheer number of insects I discovered I’m afraid I did not have the time to cross reference with other resources, but you can always look into the many resources Wikipedia lists at the bottom of each article if you want to find out more!
“Dicondylia.” Wikipedia, https://en.wikipedia.org/wiki/Dicondylia#Taxonomy
“Beetle.” Wikipedia, https://en.wikipedia.org/wiki/Beetle#Evolution
“Hydrophylidae.” Wikipedia, https://en.wikipedia.org/wiki/Hydrophilidae
“Cupedidae.” Wikipedia, https://en.wikipedia.org/wiki/Cupedidae
“Weevil.” Wikipedia, https://en.wikipedia.org/wiki/Weevil
“Belidae.” Wikipedia, https://en.wikipedia.org/wiki/Belidae
Kundrata, Robin & Pačková, Gabriela & Hoffmannova, Johana. (2020). Fossil Genera in Elateridae (Insecta, Coleoptera): A Triassic Origin and Jurassic Diversification. Insects. 11. 394. 10.3390/insects11060394.
“Bubrestidae.” Wikipedia, https://en.wikipedia.org/wiki/Buprestidae
“Scarabaeidae.” Wikipedia, https://en.wikipedia.org/wiki/Scarabaeidae
“Leaf Beetle.” Wikipedia, https://en.wikipedia.org/wiki/Leaf_beetle