“…These austral taxa generally inhabit cool, pristine environments, often upland to montane streams 61 . Noteworthy, some floristic elements recovered from the Chorrillo Formation, as well as paleosoil analysis, contrarily indicate temperate to warm conditions 23 , 72 .…”
Section: Discussionmentioning
confidence: 99%
“…The Chorrillo Formation was initially named as ‘dinosaur-bearing strata’ because of the abundance of fossil vertebrate remains that were found on these deposits 14 – 16 , 19 – 21 , 80 , 81 . However, studies carried out in the last years indicate that the Chorrillo Formation was not only rich in vertebrates but also in invertebrates, plants, and palynomorphs 14 , 17 , 22 , 23 . Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Previous uppermost Cretaceous report from insects in the region consisted of coleopteran elytra imprints presumably from the lowermost levels of the Dorotea Formation in southern Chile 12 , 13 . The Chorrillo Formation has yielded a rich and variegated fossil content 14 including titanosaurids, hadrosaurids, ankylosaurids 15 , non-avian theropods 16 , enantiornithine birds 17 , 18 , gondwanatherian and monotreme mammals 19 – 21 , turtle, frogs, and fishes 14 , 17 , terrestrial mollusks 14 , and conifer woods, pollen and spores of different plant groups 14 , 17 , 22 , 23 . The entomofauna currently recognized is composed by members of Chironomidae, Ephemeroptera, and Lepidoptera.…”
Insect faunas from the latest Cretaceous are poorly known worldwide. Particularly, in the Southern Hemisphere, there is a gap regarding insect assemblages in the Campanian-Maastrichtian interval. Here we present an insect assemblage from the Maastrichtian Chorrillo Formation, southern Argentina, represented by well-preserved and non-deformed, chitinous microscopic remains including head capsules, wings and scales. Identified clades include Chironomidae dipterans, Coelolepida lepidopterans, and Ephemeroptera. The assemblage taxonomically resembles those of Cenozoic age, rather than other Mesozoic assemblages, in being composed by diverse chironomids and lepidopterans. To the best of our knowledge, present discovery constitutes the first insect body fossils for the Maastrichtian in the Southern Hemisphere, thus filling the gap between well-known Early Cretaceous entomofaunas and those of Paleogene age. The presented evidence shows that modern clades of chironomids were already dominant and diversified by the end of the Cretaceous, in concert with the parallel radiation of aquatic angiosperms which became dominant in freshwater habitats. This exceptional finding encourages the active search of microscopic remains of fossil arthropods in other geological units, which could provide a unique way of enhancing our knowledge on the past diversity of the clade.
“…These austral taxa generally inhabit cool, pristine environments, often upland to montane streams 61 . Noteworthy, some floristic elements recovered from the Chorrillo Formation, as well as paleosoil analysis, contrarily indicate temperate to warm conditions 23 , 72 .…”
Section: Discussionmentioning
confidence: 99%
“…The Chorrillo Formation was initially named as ‘dinosaur-bearing strata’ because of the abundance of fossil vertebrate remains that were found on these deposits 14 – 16 , 19 – 21 , 80 , 81 . However, studies carried out in the last years indicate that the Chorrillo Formation was not only rich in vertebrates but also in invertebrates, plants, and palynomorphs 14 , 17 , 22 , 23 . Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Previous uppermost Cretaceous report from insects in the region consisted of coleopteran elytra imprints presumably from the lowermost levels of the Dorotea Formation in southern Chile 12 , 13 . The Chorrillo Formation has yielded a rich and variegated fossil content 14 including titanosaurids, hadrosaurids, ankylosaurids 15 , non-avian theropods 16 , enantiornithine birds 17 , 18 , gondwanatherian and monotreme mammals 19 – 21 , turtle, frogs, and fishes 14 , 17 , terrestrial mollusks 14 , and conifer woods, pollen and spores of different plant groups 14 , 17 , 22 , 23 . The entomofauna currently recognized is composed by members of Chironomidae, Ephemeroptera, and Lepidoptera.…”
Insect faunas from the latest Cretaceous are poorly known worldwide. Particularly, in the Southern Hemisphere, there is a gap regarding insect assemblages in the Campanian-Maastrichtian interval. Here we present an insect assemblage from the Maastrichtian Chorrillo Formation, southern Argentina, represented by well-preserved and non-deformed, chitinous microscopic remains including head capsules, wings and scales. Identified clades include Chironomidae dipterans, Coelolepida lepidopterans, and Ephemeroptera. The assemblage taxonomically resembles those of Cenozoic age, rather than other Mesozoic assemblages, in being composed by diverse chironomids and lepidopterans. To the best of our knowledge, present discovery constitutes the first insect body fossils for the Maastrichtian in the Southern Hemisphere, thus filling the gap between well-known Early Cretaceous entomofaunas and those of Paleogene age. The presented evidence shows that modern clades of chironomids were already dominant and diversified by the end of the Cretaceous, in concert with the parallel radiation of aquatic angiosperms which became dominant in freshwater habitats. This exceptional finding encourages the active search of microscopic remains of fossil arthropods in other geological units, which could provide a unique way of enhancing our knowledge on the past diversity of the clade.
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