Protoanisolarva juarezi, a new genus and species described from a 247-million-year-old larva, shares key features with Anisopodidae, a small cosmopolitan family of gnat-like flies known as wood gnats or window-gnats.
Triassic terrestrial larva Protoanisolarva juarezi. Scale bars – 1 mm in (A), 0.05 mm in (C-E, G), 0.1 mm in (F). Image credit: Peñalver et al., doi: 10.1002/spp2.1472.
“Insect colonization of continental aquatic ecosystems and their immediate surroundings was paramount for the establishment of complex trophic nets and organic-matter recycling in those environments,” said Dr. Enrique Peñalver, a researcher with the Spanish National Research Council at the Spanish Geological Survey, and colleagues.
“True flies (order Diptera) and other insects such as mayflies developed crucial ecological roles in early continental aquatic ecosystems, as early as the Triassic.”
“However, the mode and tempo of these processes remain poorly known, partly due to a critical fossil record gap before the Middle Triassic.”
In new research, the authors examined Middle Triassic dipteran fossils — including Protoanisolarva juarezi, the oldest record of the order — from the Pedra Alta locality, Cala d’Estellencs, Mallorca, Spain.
“The larva of Protoanisolarva juarezi, very well preserved, belongs to a group of insects that we all know, the dipterans,” they said.
“Although thousands of fossil dipterans have been found across the globe, both in thinly layered rocks and in amber, this 247-million-year-old specimen — older than the earliest dinosaurs — is the oldest dipteran ever found.”
“This record was previously held by fossils found in France, about one or two million years younger than those from Pedra Alta.”
The Protoanisolarva juarezi larva preserves both the external and internal structures of the head, some parts of the digestive system, and, most importantly, the spiracles (external openings to its respiratory system).
“If we were able to visit the region at the beginning of the Triassic, we would see large rivers and floodplains under a climate similar to that found in tropical Africa today, alternating dry and rainy seasons,” said Dr. Rafel Matamales-Andreu, a paleontologist at the Balearic Museum of Natural Sciences.
“This larva fed on organic matter from the soil ‘just’ a few million years in the aftermath of likely the most dramatic mass extinction in the history of life on Earth, which erased more than 80% of the species and led to the end of the Paleozoic Era.”
“We have been able to look at some of the adaptations by the first dipterans to the postapocalyptic environment at the beginning of the Triassic, for instance, a breathing system that is still found in different groups of insects today,” added Dr. Ricardo Pérez-de la Fuente, a paleontologist at the Oxford Universitys’s Museum of Natural History.
The team’s paper was published in the journal Papers in Palaeontology.
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Enrique Peñalver et al. 2022. Early adaptations of true flies (Diptera) to moist and aquatic continental environments. Papers in Palaeontology 8 (6): e1472; doi: 10.1002/spp2.1472
