Noctulonoid bats have developed a variety of adaptations in their jaws and teeth to cope with a diverse diet (according to the article, the diet is not diverse but variable), similar to Darwin's pharaohs. Researchers are analyzing their unique dental structure to reveal insights into the evolution of mammals, including our teeth.


Credit: Alexa Sadier

Credit: Sharlene Santana/University of Washington

**Credit:** Sharlene Santana/University of Washington

Credit: Sharlene Santana/University of Washington


Credit: Sharlene Santana/University of Washington

The evolution of Darwin's finches and noctillionoid bats
Darwin's finches, living on the Galapagos Islands, played a central role in understanding the processes of evolution. Each species developed a unique beak shape adapted to its diet, which helped Darwin develop the theory of natural selection.
A group of bats shows a similar evolutionary trajectory, but on an even larger scale. Noctulonoid bats, which live mainly in the tropics of the Americas, include over 200 species. Although genetically related, their jaws have evolved into different shapes and sizes to adapt to diverse (variable) food types.
A study published in Nature Communications suggests that the changes included adjustments in the number, size, shape and location of teeth. For example, bats with shorter snouts lack certain teeth due to lack of space, while bats with longer snouts have room for additional teeth.
Interestingly, their total number of teeth is similar to that of early placental mammals, including humans.
What can noctillionoid bats teach us about facial evolution in mammals??
According to the research team, comparing these bats may provide insights into how jaws and teeth develop in mammals in general, including humans.
"Bats have all four types of teeth—incisors, canines, premolars and molars—just like us," said researcher Charlene Santana, a professor of biology at the University of Washington and curator of mammals at the Burke Museum of Nature and Culture. "Additionally, noctulonoid bats have evolved to a wide variety of diets (foods) in just 25 million years, which is a very short period of time for these kinds of adaptations."
A variety of quick adjustments for different diets
Noctulonoid bats include species with short faces and strong jaws, capable of biting into hard fruits, alongside species with long snouts that help them drink nectar from flowers.
“The key question is how did such a wide variety evolve so quickly? What changes would have had to have occurred in the jaws and teeth to make this possible?” said lead researcher Dr. Alexa Sadier, of the University of Montpellier in France, who began the study as a research fellow at the University of California, Los Angeles.
Today, bats from this group feed on insects, fruits, nectar, fish, and even blood – as they also include the infamous vampire bats.
Scans CT Revealing the laws of development behind teeth
To investigate the phenomenon, the researchers performed CT scans and compared the jaw and tooth structure of more than 100 species of bats, combining specimens (individuals?) from museums and a few individuals captured in the wild for research.
The researchers analyzed the relative sizes of teeth and different cranial adaptations among species with different diets, and used mathematical models to examine how these differences arise during evolution.
The researchers found that there are "developmental laws" that dictate the adaptation of teeth to the bat's diet:
- Bats with long jaws (such as those that feed on nectar) tend to retain a full set of molars and premolars.
- Bats with short jaws (mainly fruit eaters) tend to lose either the middle premolar or the back molar, and sometimes both.
"When there's more space, there are more teeth," Sadier explained. "But when space is limited—like in short-jawed bats—there's just not enough room for all those teeth."
The study also showed that the first tooth to appear tends to be larger, as there is not enough room for the subsequent teeth to grow.
"This study allows us to test hypotheses about how the structure, size and shape of teeth are determined in mammals," Santana said. "Despite the great importance of teeth, we still know very little about their developmental processes."
Most studies of tooth development in mammals have been conducted in mice, which have only specially adapted molars and incisors. It is still unclear whether the genes that control tooth development in mice also function in mammals with more primitive tooth systems, such as bats and humans.
Ongoing research to uncover the secrets of evolution
Sadier, Santana and their colleagues are continuing to expand the research and also examine the development of the incisors and fangs of noctilucent bats.
"The evolutionary pressures on these bats are so strong – the structure has to fit perfectly."
"Dead to function," Santana said. "I believe there are still some hiding here." Many evolutionary secrets "That we are only beginning to uncover."
More of the topic in Hayadan: (Beresheet is the Hebrew name for the book of Genesis)