Paleontologists have discovered three racewing larvae in Myanmar's 100 million Kachin amber with large forward trunks (the eyes of Holometabolan). These specimens show highly developed, simple eye convergent evolution of at least two additional lines, indicating the enormous diversity of Cretaceous larvae.
A larva from Kachin Amber, 100 million years ago. Image credit: Haug et al. , doi: 10.1111/1744-7917.13509.
Adult insects are known for their fascinating and complicated eyes. This allows you to achieve amazing sensory feats when performing functions such as food and peers search.
However, in many insect larvae, these eyes are not yet developed. The simple eyes known as the stem are usually sufficient for these larvae. Often, it is a machine that is mostly eating at this stage.
However, some insect larvae are predators, and a few of these have developed highly efficient imaging systems from simple stems.
“The adults and pups of beetles, bees, flies, butterflies and close relative insects also have complex eyes that are present in some larvae,” says Dr. Carolin Haug, researcher at Ludwig-Maximilians-Universität München.
“In contrast, most holometaboran larvae have a small group of up to seven simple eyes, known as stems, on either side of the head.”
“The trunk is inherent to holometaborane, usually a simple structure, often slightly radial oriented, creating a wide field of view.”
“However, the fields of the right and left trunks rarely overlap, but denies binocular vision in the larvae.”
“And more, most stems lack the complex internal structures needed to create images.”
“In contrast, several predatory holometaboran larvae evolved anteriorly directed stems, which were expanded with overlapping fields of vision that promote binocular vision.”
“Examples include the larvae of diving beetles known as water tigers, tiger beetles, anthraion and the Whirlgihi beetle.”
“The trunk has been reported in over 120 fossil larvae, but no imaging eyes have been identified that allow binocular vision.”
In a new study, the authors discovered three predatory larvae with unusually large and positive trunks in the Cretaceous Cachin Amber.
They found that the size and orientation of the larvae eyes are comparable to the size and orientation of modern anthraions, allowing for similar optical resolution.
“This is evidence of the first fossils of such an eye and therefore the oldest,” Dr. Haug said.
“The highly refined, simple eyes of predatory larvae evolved with a further double convergence, not just anti-, water tigers and tiger beetles, but also at least among extinct larvae.”
“Our results reveal greater diversity in morphology, ecology, and feeding strategies among Cretaceous larvae than today.”
Survey results Published in the journal Insect Science.
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Karolyn Haug et al. Cretaceous horny larvae with binocular vision show convergent evolution of refined, simple eyes. Insect SciencePublished online on February 18th, 2025. doi:10.1111/1744-7917.13509
Source: www.sci.news
