While the theory’s logic seems sound, evolutionary biologists have poked holes in Dollo’s Law with examples ranging from lizards redeveloping egg-laying to stick insects losing and then regaining wings.īut the re-evolution of teeth in G. An organism cannot re-evolve something its ancestor lost, like how humans have not re-evolved tails, the thinking goes. Coined by the palaeontologist Louis Dollo, the theory posits that once a trait is lost in a group of organisms, it is gone for good. These findings provide tantalising evidence disproving a century-old evolutionary theory known as Dollo’s Law of Irreversibility. To begin with, Paluh and colleagues have shown that these teeth are indeed genuine, and formed by bony tissue called dentin and encased in enamel, refuting suggestions that these structures were possibly “pseudo-teeth.” The researchers also found that these teeth, sourced from the University of Kansas Museum of Natural History, closely resemble teeth those along the upper jaws of other marsupial frogs-making them more likely to be the real deal. So why does Guenther’s marsupial frog have teeth, and how did they arise? Around 230 million years ago, the ancestors of modern frogs lost the teeth along their bottom jaws for good. The study also helps resolve other questions. The images and analysis, published November 10 in the journal Evolution, provide the first in-depth glimpse of the species’ jaws and teeth. guentheri specimens preserved for decades in alcohol. Along with colleagues at the Florida Museum of Natural History, he used a micro-CT scanner to peer into the skulls of six G. This lack of study has left many questions outstanding, including a very simple one: What does this weirdo frog’s jaw look like?ĭaniel Paluh, a herpetologist pursuing a PhD at the University of Florida, wanted to fill in this gap in knowledge. As a result, no real images of the teeth themselves existed. There are precious few samples of the animals in museum collections-less than 30 specimens may exist in the entire world.
Unfortunately, this species hasn’t been sighted since 1996-and even before then, was seldom found or studied. But virtually all 7,000 species of living frogs lack teeth along their lower jaws-except for G. Frogs have teeth? Actually, yes: Most frogs have a small number of them on their upper jaws.
Like other marsupial frogs this species, known as Gastrotheca guentheri, doesn’t produce free-swimming tadpoles, but rather rears its young under a flap of skin on its back.īut it has one even more puzzling trait: It possesses a full set of teeth. Long-limbed and sporting dramatic horns above its eyes, Guenther’s marsupial frog is a bizarre-looking amphibian from the misty cloud forests of the Andean slopes.