Paleontologists don’t always get what they’re looking for. In January 2020, a team from the Argentine Museum of Natural Sciences and the Chinese Academy of Sciences hoped to discover feathered dinosaurs in what is now Patagonia. They didn’t discover dinosaurs, but instead discovered the oldest known fossil tadpoles.
“Paleontologists have discovered hundreds of adult specimens of the basal ghost frog, the ancestor of frogs and toads.” mariana chubarsays a biologist at Maimonides University in Buenos Aires. Popular science. “After many days of digging, one of our team members discovered a stone with a specific imprint on it. It was a fossilized tadpole.”
This 161-million-year-old specimen sheds light on the evolution of frogs and toads. is explained in The study was co-authored by Chuliver and published in the journal Oct. 30. nature.
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Earth frogs and toads belong to the group of tailless amphibians. anuran. The two-stage life cycle when an aquatic tadpole transforms into its adult form is one of the main characteristics of anurans. Adult frogs are recorded in the fossil record from about 217 to 213 million years ago, during the Late Triassic Period. However, tadpoles have not been seen before the Cretaceous period (about 145 million years ago).
in new researchthe research team describes this well-preserved fossil tadpole. belongs to seed Notobatrachus degiustoi Its origin dates back to the mid-Jurassic period, approximately 168 to 161 million years ago. Most tadpoles are only about an inch long, so a fossil tadpole measuring about 6.2 inches long is considered a giant.
In evolution, gigantism This is the result of the species evolving a larger body size compared to its smaller-bodied ancestor. There are many adults Notobatrachus degiustoi Frogs are also considered giants, and gigantism has evolved many times in anuran history. According to research, this is one of the few species that has both a giant tadpole and a frog.
“adult” Notobatrachus degiustoi “It was a large toad that probably had an insectivorous feeding style and was closely associated with bodies of water,” Chubar said. “The habitat this species lived in was probably a shallow pond, which periodically dried up as climatic conditions were changing.”
In this shallow water, various plants, bivalves, brachiopodand insects. Notobatrachus degiustoi Tadpoles are also filter feeders, pumping water into their gill chambers to filter out food particles. This feeding system is still present in living tadpoles, and this fossil is important evidence that it had already evolved in early anurans. Approximately 161 million years ago.
The fossil shows most of its body and part of its tail, as well as its eyes, nerves, and forelimbs. This suggests that the tadpoles were in a later stage of metamorphosis.
[Related: Blind tadpoles learn to see using eyeballs attached to their butts.]
“The most surprising part of this study was when we put the tadpoles under a binocular microscope and saw that the gill skeleton and other soft tissues, such as neural traces, were beautifully preserved,” Chubar said.
They were able to confirm some of these. The main features of the tadpole’s body plan were already present This was early in the evolution of anurans.
“We were very surprised that some of the characteristics commonly used to classify extant tadpoles were preserved in this fossil, so we were able to classify this tadpole,” said Chubar. says.
