Butterflies appeared before flowers
The two paleontologists dissolving rock cores more than 200 million years old were looking for vestiges of freshwater algae. Instead, tiny fragments of insect scales caught their eye — remnants that a report published Jan. 10 identifies as the oldest evidence of butterflies and moths.
A series of fortunate events led to this discovery, which dates the insects to around 70 million years earlier than previously known, well before there were flowers around that they could pollinate.
In the fall of 2012, Paul K. Strother of Boston University, an expert in prehistoric pollen and spores, traveled to Germany to the lab of Bas van de Schootbrugge, a fellow microfossil paleontologist. There they dissolved cores dating to the late Triassic and early Jurassic periods by exposing the material to a nasty acid. The acid erased everything but fossilized organic material.
What grabbed Mr. Strother’s attention were infinitesimally tiny scales. “It struck me that these looked like butterfly scales,” he recalled.
Butterfly and moth wings are covered in tiny scales that overlap like shingles on a roof. The scientists contacted experts studying modern insects, who deflated their hopes of identifying butterflies. The scales were described as “not diagnostic,” Mr. Strother said, meaning they did not belong only to a specific insect group. Some mosquitoes and flies have scales, too.
About a year later in Paris, Mr. Strother found himself seated at a dinner near a man named Torsten Wappler. The University of Bonn scientist, an expert in extinct insects, had just published an extensive phylogeny, or family tree, describing 479 million years of insect evolution. Mr. Strother, who kept images of the curious scales on his computer, whipped out the photos. Mr. Wappler examined them and told Mr. Strother that it would be possible to classify the insects. It would just take a lot of grunt work down the barrelof a microscope.
Mr. Van de Schootbrugge enlisted an undergraduate student named Timo J.B. van Eldijk. “Timo is the guy that did all the work,” Mr. Strother said.
The acid reduced the rock cores to what Mr. van Eldijk called “black organic smudge.” Out of this smudge he had to isolate the scales, which to the naked eye look just like a pile of dust. He embedded the dust in a mixture of glycerol and water. Then, using a needle tipped with a human nose hair, Mr. van Eldijk managed to prod the scales into of co-evolution, butterflies view beneath an electron developed proboscises in response microscope. to plants that developed
His investigation revealed flowers. The more intricate that the scales were divided the flower’s nectar into two types. One set of spur, the more intricate the scales was solid all the way insect slurper became. through and compact as Charles Darwin once received steamrolled almonds a box containing an — “primitive,” Mr. van orchid with an exceptionally Eldijk called them. The other long and slender spur. scales were hollow, which “Good Heavens, what insect proved to be the critical discovery, can suck it,” he wrote in an he said. 1862 letter to a friend. Four
Previous studies of insect decades later, biologists in phylogeny had shown the Madagascar discovered an earliest moth and butterfly African hawkmoth with a families with solid scales, wiry proboscis more than Mr. van Eldijk said. They 10 inches long. also had mandibles for But plants did not evolve chewing food. The insects flowers until 130 million that later split off the family years ago, according to the tree developed hollow earliest fossil flowers. scales in their wings. And “There’s two possible scenarios these younger moths and if these [insects] really butterflies also grew proboscises: are pollinators” with long sucking tubes proboscises, Mr. Strother for drinking plant nectar said. Maybe there is a missing that curled like crazy record of Triassic or straws beneath their heads. early Jurassic flowers. Or
In the textbook example maybe the proboscis came first — the scenario that the study authors hypothesize is more probable.
“During the Jurassic, the most dominant group of plants were the gymnosperms, like your classic pine tree,” Mr. van Eldijk said. Conifer cones have indentations to catch male pollen. Insects might have drunk this pollen, if they had tubular mouths.
The new research, published in Science Advances, also reveals that moths and butterflies are survivors. At the end of the Triassic period, 201 million years ago, the world was going through an upheaval. Many marine species and some land animals went extinct. Some scientists suggest that intense volcanic activity wracked the planet, altering its climate. But moth and butterfly scales are present in the rock cores on both sides of the extinction divide.