Most bats patrol the night sky in search of insects. New World leaf-nosed bats take a different approach. Among the more than 200 species of leaf-nosed bats, there are also those that hunt insects. drinking nectar; eat fruit; pollen; blood sucking; and prey on frogs, birds, lizards and even other bats. They are among the most ecologically diverse mammals in the world, and until recently, were thought to have originated in South America.

“The theory that people have put forward is that they first got to South America, where their only competition was insectivorous bats. So they developed a bunch of different feeding strategies, ” said Gary Morgan, curator of vertebrate biology in New Mexico. Natural History Museum.

A new discovery suggests the story may be more complicated. In an article published by Journal of Mammalian Evolution, Morgan and colleagues described the oldest known leaf-nosed bat fossils, found along the Panama Canal. They are also the oldest bat fossils from Central America, preserved 20 million years ago when Panama and the rest of North America were separated from the southern landmass by a seaway at least 120 miles wide.

Based on these and other fossils, Morgan believes that previous research may have identified the wrong continent as the birthplace of leaf-nosed bats.

“We think they may have a northern origin.”

A once-in-a-century opportunity leads to many new discoveries.

In 2007, hundreds of engineers, excavators and geologists gathered in Panama to begin the daunting task of widening and deepening the country’s historic canal. Biologists were not far behind. After work crews used dynamite to blow up parts of the bank, the researchers dug in to remove pieces of the fossil from the rubble. The bones trace the largest migration of animals in Earth’s history, and the expansion of the canal marked the first time anyone had seen it up close.

About 5 million years ago, shifting tectonic plates created a land bridge between North and South America. After more than 100 million years of separation, animals in the Northern Hemisphere could freely travel south and vice versa.

“Animals like sloths and armadillos moved north, while horses, tappers, bears and elephants moved south,” said study co-author Bruce McFadden, curator of vertebrate biology at the Florida Museum of Natural History. This event is called the Great American Biotic Interchange, and it helped shape the current distribution of countless plants and animals across the American continents.

If the Panama Canal had not been built, it is likely that this event would still remain a mystery to scientists.

“This suggests that the Panama Canal Basin, which was part of North America at the time, was full of the kind of mammals you’d find in Nebraska or Florida rather than South America,” says Jonathan Bloch, a Florida vertebrate scientist. Curator of Biology said. Museum

Rare fossils provide clues to the origin of leaf-nosed bats.

Almost all the animals found in fossil beds of similar age near the Canal Zone represent the southernmost range of species from high latitudes. Bears were dogs. Small horse rhinoceros; Camels are early relatives of modern hippos; ungulates with horns protruding from their heads and snouts; and at least one species of chalicothere, a strange animal that resembles a sloth grafted onto a giraffe with a horse.

The first South American mammal to be discovered in the old beds was from a primate species, which is believed to have migrated up the seaway.

The leaf-nosed bat is the second South American mammal found at the site. This may suggest that the animals were better at crossing the sea barrier than previously thought. The strait separating North and South America was five times wider than the modern Strait of Dover between England and France and 15 times wider than the Strait of Gibraltar, which separates Europe from Africa.

Yet other animals seem to have had little trouble making the journey. The list of non-mammals that have made their way from south to north includes a boa constrictor, a crocodile and a frog. There is little doubt about where these creatures came from, but the fossil record for leaf-nosed bats is more ambiguous.

Today, leaf-nosed bats are distributed from South America through Arizona. Although they have been around for about 20 million years or more, they have left behind surprisingly few fossils. Three extinct species in this family of similar age to the Panama specimen have been found in Colombia, and fossils of much younger vampire bats have been recovered from several sinkholes in Florida. Beyond that, there’s not much for biologists to do.

Zooming out makes things even more dangerous. Two closely related families of fossils found in Florida are the South American leaf-nosed bat and fossils of their relatives dating back 10 million years.

More fossil discoveries will be needed to determine where leaf-nosed bats came from and why they developed such a diverse and refined appetite. Fortunately, there is no shortage of fossils from the canal. Although the expansion project lasted only nine years, the biologists collected enough material to keep them busy for the foreseeable future.

“Time was of the essence, so we collected fossils much faster than science,” Bloch said. “There are probably fossils from this project that will be described 50 years from now.”

Nicholas Szeplowski of the Oklahoma Museum of Natural History, Aldo Rincon of the Universidad del Norte and Aaron Wood of Iowa State University also co-authored the study.