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10 Intriguing Ancient Insect Fossils
Insects are everywhere. They are the most diverse group of creatures on the planet, with over 900,000 species identified and named. This represents around 80% of all the animal species that have been discovered. In terms of sheer numbers and mass, insects are overwhelmingly the dominant lifeforms on Earth.
It is thought that insects evolved around 480 million years ago, at around the same time plants made the move to land. Since then, they have exploded into a bewildering variety of forms with incredible adaptations. Because they lack hard internal skeletons, the fossil record of this evolution is somewhat patchy—but many fossil insects have been discovered. Here are ten of the most intriguing.
10 Butterfly Scales
Butterflies and moths are delicate organisms that flutter through the air on wings coated with minuscule scales. They belong to an order of insects called Lepidoptera. The scales provide a number of benefits, but the most obvious is that they can scatter light to create vivid colors and patterns. This is achieved through tiny structures on their surface that diffract light.
Despite being among the tiniest parts of a butterfly, the fossilized scales are the oldest evidence of moths and butterflies ever discovered. Dating to around 200 million years ago, they were recovered from a 10g sample of sediment dug up in Germany. From this one sample, which once sat at the bottom of a lagoon, seven different species of Lepidoptera were discovered.
9 Lacewing Larvae
Amber is the perfect medium for preserving ancient insects. When an insect becomes engulfed in sticky sap, their life may end, but their afterlife might be guaranteed. The sap solidifies and undergoes chemical changes to become amber—and the exterior of the insects is perfectly preserved.
One hundred million years ago, the predatory larvae of a lacewing fly had the bad luck of crawling into some sap. Today, lacewing larvae feed on soft and easy prey, but these ancient ones had long and sharp mouthparts, which suggests they hunted animals that needed to be kept at a distance in case they fought back. The amber-bound larvae also have other extreme modifications compared to their modern relatives. Maybe life in the Cretaceous period was tough.
8 Ancient Insect Camouflage
Many insects are masters of camouflage. This can be used to hide the insects from a predator or from their prey. Camouflage can take many forms, but perhaps the strangest that insects employ is the wearing of dead bodies to disguise themselves. Assassin bug larvae will pile the corpses of ants onto their backs.
This debris-carrying behavior has evolved multiple times in various insect lineages, and sometimes, it has been captured in amber. In one case, the larva of a lacewing, yes them again, from over 100 million years ago was seen with dismembered parts of other arthropods stacked on its back. Another insect larva, named Hallucinochrysa diogenesi, was found to have draped filaments from a plant over itself. Both these behaviors required multiple evolutionary changes to make the debris stick in place, suggesting this form of camouflage emerged even earlier in history than we know.
7 The Insect Alien
You never know what insects will emerge from amber deposits, and sometimes, the results can be terrifying. When one researcher discovered an insect fossil that looked like a science fiction alien, he crafted a Halloween mask resembling it. He had to take the mask off, however, after it scared trick-or-treaters who visited his home too much.
The insect, dating to around 100 million years ago, was so bizarre that it was decided that it belonged to a wholly unknown order of insects known as the Aethiocarenodea. Discovering a new order of insects is incredibly rare as, despite there being nearly a million species of insects, they all belong to just 32 orders.
The new insect—Aethiocarenus burmanicus—is marked by a triangular head, which has only a narrow attachment to the body. By turning its head, the insect would have been able to see directly behind itself. There is also evidence from the fossil that it could produce a substance from one of its glands that would deter predators—just as it deters trick-or-treaters.
6 Insect with Bulging Eyes
Being able to see behind you by turning your head is pretty cool, but what about having 360-degree vision at all times? For that, you need either lots of eyes or eyes that are weirdly shaped and positioned. An insect trapped in amber has been discovered that has a pair of eyes that stick out from its head like light bulbs, giving it this unique ability.
Palaeotanyrhina exophthalma, the second part of its name means “outside eyes,” used its full range of vision to help it hunt for prey. Once located, the insect moved in and snatched them up with its modified front legs. These had special glands that produced a sticky substance that would have snared whatever it managed to grasp. It’s ironic then that this sticky-hunter came to a sticky end of its own when it wandered into sap.
5 Insect Ears
Bats have been blamed for a number of changes in insect evolution. Many bats feast on flying insects, so an evolutionary arms race has developed between bats looking to hunt them and insects seeking to avoid becoming a meal. It was widely thought that butterflies developed from moths that stopped flying at night to avoid bats when they evolved around 50 million years ago. It was also thought that many insects developed sensitive hearing to detect the echolocation used by bats. We now have evidence that neither of these was the case.
By studying fossils that date before the evolution of bats, we know that several insect groups had developed a keen sense of hearing. Well-preserved fossils of crickets and katydids from 50 million years ago show the same organs of hearing located behind the knees as modern species. This means that they must have evolved before bats appeared on the scene.
The ability of insects to hear has evolved at least 17 different times in history due to the different strategies that different groups use to pick up sound.
4 The “Frankenstein” Insect
The past is a foreign country; they do things differently there. Even insects acted differently in the past. Today, mayflies are known for their strange life cycles, where they spend the majority of their time as larvae and emerge as adults for just a few hours or days. In that brief time, all they do is mate and produce the next generation of mayflies—they don’t even eat. Yet fossils of an early relative suggest things were not always this way.
Called Coxoplectoptera, these insects date to around 120 million years ago. They have been described as Frankenstein creatures because they join together features never before seen in a single species. Their wings were like those of a dragonfly, though with the vein pattern on the wings of a mayfly, and they had the front legs of a praying mantis. Unlike mayflies, perhaps their closest living relatives, the adults of this species clearly hunted and ate while they were adults.
3 Pollen-Carrying Insects
When we think of insects as pollinators of plants, we probably picture happy little bees flitting from flower to flower. But flowers probably only evolved around 140 million years ago, and we have evidence of insects carrying pollen that date from 280 million years ago.
Plants had reproduced using pollen for millions of years before flowers developed, but pollen was primarily spread passively by the wind. They may have had some help from insects, however. By examining hundreds of fossils of an insect called tillyardembiids, researchers realized that six of them had pollen stuck to their heads, bodies, and legs. It is thought that the insects climbed into the cones of conifers and ate the pollen that they found there.
The pollen came from a narrow range of species, which suggests the insects were specialized feeders. It cannot be proved that the insects pollinated the plants they visited. Still, it is a fairly safe bet that, at least sometimes, the insects carried pollen from one plant to another and helped them reproduce.
2 The Oldest Insect Fossil
In the 1920s, a fossil was discovered in Scotland that dated to around 400 million years ago. Unfortunately, it was tiny and only a small fragment of the whole organism. By using the microscopes of the time, not much could be said about it other than it might be related to insects in some way. In 2004, it was re-examined, and researchers were startled to discover that it matched insects today.
The fossil of Rhyniognatha hirsti is essentially just the mouth parts of the animal. The mandibles of the creature are triangular in shape and look very much like those belonging to flying insects. There are no fossils of flying insects from before 325 million years ago, but this fossil might hint that flying evolved much earlier than we had thought.
Unfortunately, the fossil comes from the remains of a hot spring, so it is unlikely that a fossil with the insect’s wings intact will ever be discovered. Throwing your samples in a boiling pond is not the best way to preserve them.
1 Insect in Opal
Opals are among the most spectacular precious stones found on Earth, with their vivid colors that shimmer as you move them. In one case, however, it was not the play of light in the opal that astounded people; it was a fossil insect.
This seems to be incredibly unlikely, potentially impossible because opal usually forms from small balls of silica settling in water. This is not the ideal condition for any insect to be fossilized. But in the example from Java, dating to around six million years ago, the insect can be clearly seen. You can even see its open jaws, antennae, and the minuscule hairs on it. There are many questions as to how this fossil could have formed, and many models have been proposed. While it was a unique find, the authenticity of the fossil could be questioned entirely.
Since the appearance of the first insect in opal, a second example has been recovered from the same site in Java. However the fossil came about, it seems there may be more pretty insects in opal waiting to be dug up.