Fossil Friday: Insects Part 3

So many insects have the word “fly” attached to their names that I thought I should pause a moment to recognize the insects known as “true flies” before moving on to other insects.

“True flies” can typically be recognized by having only two wings (Diptera is from the Greek di “two” + pteron “wing”). What would normally be a second pair of wings in other insects is a pair of highly specialized organs called halteres, which are basically high-speed sensors that allow the fly to make the acrobatic aerial maneuvers that so often frustrate us when trying to squash them when they invade our homes.

Flies are an incredibly diverse group, so this is only a glimpse at the true diversity (and possible annoyance for local dinosaurs) of these insects during the Jurassic period. Mosquitoes are a rather infamous fly relative that had their earliest beginnings in the Jurassic, but these relatives did not look very much like their modern counterparts, so I have not included them here. Come back during the Cretaceous if you really want to see mosquitoes featured here.

This ancient group of tiny flies are among the first “true flies” to appear in the middle and late Triassic Period. Only one genus has survived to the modern day, a native of Idaho in the USA that likes to stay near running water.
An ancient group of tiny flies known as Nymphomyiidae that may have appeared as early as the Triassic. The few surviving members of this group live along fast-flowing streams in Quebec, the Himalayas, and Japan, where the people in Uenomura, Japan have given them the colloquial name of Ueno Powder Fly.
These flies are much larger than their other ancient relatives, and are easily recognized by their slender bodies and long, stilt-like legs. Most are either predatory and hunt other insects and flies, or else are biting flies and have been a painful nuisance to animals since the Triassic Period.
Gnats have been infesting rotting vegetation and moldy soil ever since the Late Triassic Period. Their tiny grubs help speed up the process of decay, and clean up rotting refuse. They are tiny insects, no bigger than a few grains of salt, and are often recognizable for the clouds or “ghosts” they form when they swarm together. The males are typically the ones who begin this aerial dance, usually at dusk, and the females join them when ready.
Horse-flies and their immediate relatives have been biting animals since the Late Jurassic. Only the females do this, since they need the extra iron and protein to lay eggs. The males are often important pollinators, like most of their other fly cousins, and enjoyed the sweet nectar that oozed from the cones of cycads and related plants of the time. Earlier relatives that were closely related and very similar in appearance were a group called Eostratomyiidae. They are known to live during the Middle Jurassic Period.
These miniscule flies (less than 5mm) appeared in the Middle Jurassic Period. In modern times they are found much more commonly in arid and desert regions, though they are extremely diverse and known all over the world, and in all habitats except the tallest mountains and the poles. They may look a bit like mosquitoes, but these flies do not bite.
The oldest fossils of these flies were found in Middle Jurassic rocks of the Karabastou Formation, in Kazakhstan. The larvae, or grubs, are predatory and most often parasitic of other insects, while the adults enjoy flowers. Of course, with no flowers in the Jurassic, they probably enjoyed the sweet-smelling, syrupy, and often brightly colored cones of cycads and their relatives.


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.

* I must add here that this was not true for the flies. A few groups had convenient time charts, but for the most part I had to crawl in the weeds and cross reference species or family name with the common name, because oftentimes these would be two separate articles on Wikipedia, with different information. I often stumbled across information for one I’d previously researched while following a rabbit trail for a completely different group, so there were a number of last minute additions and I barely completed this post in time! Bottom line, insects just aren’t as interesting to the general populace as big dinosaurs are, so it was a great challenge to find information on these. There’s no way I’m just going to slap a house fly up here with a blanket statement that flies showed up in the Triassic and then diversified in the Jurassic, they’re just too interesting once you take a closer look at all the different shapes and body plans! πŸ˜€

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! πŸ˜€

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,

“Fly.” Wikipedia,

“Brachycera.” Wikipedia,

“Tabanomorpha.” Wikipedia,

“Horse-fly.” Wikipedia,

“Rhagionidae.” Wikipedia,

“Nemestrinoidea.” Wikipedia,

“Nemestrinidae.” Wikipedia,

“Mythicomyiidae.” Wikipedia,

“Asiloidea.” Wikipedia,

“Bibionomorpha.” Wikipedia,

“Deuterophlebia.” Wikipedia,

“Nymphomyiidae” Wikipedia,

“Flyfishing Field Note: Ueno Powder Fly.” SST’S sield sketch,

  • The above link is a Japanese page, so I had to translate its contents with Google translate. I apologize if “powder fly” is a Google translate debauchery of the original words, and welcome the proper translation if there is one. Thank you!

“Rhagionidae.” Wikipedia,

5 thoughts on “Fossil Friday: Insects Part 3

  1. Very interesting! You made the mountain midge look so pretty, haha. That takes skill! I never really thought I’d call flies “cool,” but after reading this post, it’s pretty amazing to see all the variety and diversity! I can only imagine how hard it was to find info for these guys and pull it all together. Flies need more love, lol. πŸ˜›


    1. Thank you! I’m glad you liked it!
      Yeah, who knew flies could be so interesting? I agree, the cleaner, not so well-known flies need more love, but I think the common house fly and horse flies deserve their status. The first have habits too gross to be reconciled with, and the horse-flies are too painful. But it’s unfortunate their reputation rubs off on the other ones. There are actually some pretty ones in here, and all are essential for their respective food chains. πŸ™‚

      Liked by 1 person

  2. Very interesting. I am glad that you mentioned that some flies are helpful pollinators. When did the modern house fly evolve? Even the modern house fly has evolved over the past 50 years or so. I remember when I was a kid of 6 years of age I could easily catch house flies with my bare hands. They also would fly straight to the windows and kept bumping into glass attempting to get back outside. It is not like that anymore. You rarely see a fly head to the windows. They will usually hide somewhere in the house. They will spend a lot of time crawling and staying hidden instead of flying. And do you ever wonder how they get into the house unnoticed? Through the doors of course but they will stay clinging to the door until someone opens it and often fly into the house unnoticed. If the common housefly was not observed doing this 50 years ago I doubt if the Jurassic flies had the speed, agility and “instinct” to do anything like the modern house fly can do.


    1. Hi, I’m glad you liked it! πŸ™‚

      The common house fly appeared in its modern form in the cenezoic era, so basically same as us. But of course every creature is in a constant state of adaptation and change. Flies have a much shorter lifespan, and so take less time to change. Darwin’s finches took about 20 years or so to see changes in beak shape according to changes in their environment. House flies have simply adapted to modern human environments over time. πŸ™‚ Jurassic flies had to have equally sharp instinct to survive, or else they wouldn’t be the hugely successful group that they are. It’s just different compared to the environment modern flies are exposed to. πŸ™‚


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