[Taxacom] Triassic-Jurassic Glossatan Leps

John Grehan calabar.john at gmail.com
Wed Jan 10 14:42:52 CST 2018

For those interested -

Nice article demonstrating the truism that all fossils are the minimum age
of taxa and all molecular extrapolations are also minimums (no matter how
loud the protestations). Also note the inclusion of fairy tales about the
origin of the proboscis. Makes my earlier point quite well.

A Triassic-Jurassic window into the evolution of Lepidoptera

On the basis of an assemblage of fossilized wing scales recovered from
latest Triassic and earliest Jurassic sediments from northern Germany, we
provide the earliest evidence for Lepidoptera (moths and butterflies). The
diverse scales
confirm a (Late) Triassic radiation of lepidopteran lineages, including the
divergence of the Glossata, the clade that comprises the vast multitude of
extant moths and butterflies that have a sucking proboscis. The
microfossils extend
the minimum calibrated age of glossatan moths by ca. 70 million years,
refuting ancestral association of the group with flowering plants.
Development of the proboscis may be regarded as an adaptive innovation to
sucking free liquids for maintaining the insect’s water balance under arid
conditions. Pollination drops secreted by a variety of Mesozoic gymnosperms
may have been non-mutualistically exploited as a high-energy liquid source.
The early evolution of the Lepidoptera was probably not severely
interrupted by the end-Triassic biotic crisis.

Discussion excerpt

The transition to exclusively feeding on liquids was most likely an
evolutionary response to widespread heat and aridity during the Norian
(19). When flying in dry air, the high ratio of surface area to volume
inherent in the small body size of basal moths would intensify evaporative
losses of body moisture (20). Because free liquid drinking is an efficient
technique to replenish lost moisture and survive desiccation stress,
substitution of mandibulatemouthparts by a sucking proboscis could be
seen as an adaptation to adequate maintenance of body water balance of
small, short-lived moths.


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