Paleontologists have discovered the well-preserved fossilized remains of an early anuran tadpole. Notobatrachus degiustoi At Estancia La Matilde in Patagonia, Argentina.
Frogs and toads belong to a group of tailless amphibians called anurans.
They are characterized by a biphasic life cycle, with an aquatic larval (tadpole) stage followed by an adult (frog) stage.
Adult anurans remain in the fossil record until the late Triassic period (approximately 217 to 213 million years ago), but tadpoles have not been recorded before the Cretaceous period (approximately 145 million years ago). Not yet.
“Tadpoles are free-living, non-reproductive anuran aquatic larvae that undergo morphological and ecological changes over a short period of time before reaching the adult reproductive stage. “We need to go through a metamorphosis stage that involves profound changes in our lives.” And her colleagues.
“This rapid metamorphosis in anurans is the most extreme among extant tetrapods, with tadpoles representing a highly derived larval stage.”
The authors examined well-preserved tadpole fossils. Notobatrachus degiustoi from Formation of La Matilde In Patagonia.
This giant anuran lived during the Middle Jurassic Period, 168 to 161 million years ago.
This species is also represented by a large number of excellently preserved adult specimens from the same locality.
Notobatrachus degiustoi Tadpole. Image credit: Chubar others., doi: 10.1038/s41586-024-08055-y.
According to the team, the tadpoles Notobatrachus degiustoi It was almost 16 centimeters (6.3 inches) long.
The head, most of the body, and part of the tail were visible, as were the eyes, nerves, and forelimbs, suggesting that the tadpole was in a later stage of metamorphosis.
Together, they show that key traits of today’s tadpoles, such as filter-feeding systems, had already evolved in early anurans about 161 million years ago.
“The exquisite preservation of the tadpole, including its soft tissues, shows features related to the filter-feeding mechanism characteristic of living tadpoles,” the researchers said.
“What is noteworthy is that both Notobatrachus degiustoi Tadpoles and adults reached large sizes, proving that tadpole gigantism occurred among stalked anurans. “
“This new discovery suggests that a biphasic life cycle in which filter-feeding tadpoles live in aquatic, ephemeral environments was already present in the early evolutionary history of sessile anurans, and that at least 161 million It has been shown to remain stable over the years.”
of findings Published in this week’s magazine nature.
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M. Chubar others. The oldest tadpoles reveal the evolutionary stability of anuran life cycles. naturepublished online October 30, 2024. doi: 10.1038/s41586-024-08055-y
Source: www.sci.news
