Scientists have found the oldest fossil of a giant tadpole, which moved more than 160 million years ago.
The recent fossil discovery in Argentina predates the former ancient record holder by roughly 20 million years.
Embedded in a sandstone slab are fragments of the tadpole’s skull and spine and markings of its eyes and nerves.
“It’s not only the oldest tadpole known, but also the most exquisitely preserved,” said study author Mariana Chuliver, a biologist at Buenos Aires’ Maimonides University.
World’s oldest
Scientists know frogs existed and jumped as far back as 217 million years ago.
The specifics of how and when they started developing as tadpoles are still uncertain.
This recent finding provides more insight into that timeline. Measuring approximately six inches (16 centimeters) long, the tadpole represents a younger stage of an extinct giant frog.
The fossil resembles today’s tadpoles, even featuring remnants of a gill scaffold system that contemporary tadpoles utilize to filter food particles from water.
The results were published on October 30 in the journal Nature.
Dates back to the Jurrasic era
Today, tadpoles show a lot of different shapes and play important roles in their environments.
However, scientists have found no tadpole fossils older than 145 million years, which makes it difficult to understand where they came from and how they evolved early on.
The fossil record of adult frogs (anurans) goes back to the Early Jurassic period. Similar species existed in the Late Triassic, about 217 to 213 million years ago.
Researchers have discovered a late-stage tadpole of a frog called Notobatrachus degiustoi. This frog lived in Patagonia during the Middle Jurassic period, around 168 to 161 million years ago.
This discovery is important for two reasons: it is the oldest-known tadpole and, as far as we know, the first larva of a stem-anuran.
This specimen is well-preserved, including its soft tissues. It displays features linked to the filter-feeding way of eating that we see in today’s tadpoles.
Both N. degiustoi tadpoles and adults grew large, showing that tadpole gigantism happened in early frogs.
A new discovery shows that stem-anurans’ early history includes a life cycle with filter-feeding tadpoles living in temporary water environments. This pattern has continued for at least 161 million years.
This discovery comes a day after scientists found the world’s second-smallest toad.
World’s second-smallest toad
Scientists found the second-smallest vertebrate globally in Brazil’s Atlantic Rainforest.
This diminutive animal, a flea toad, is so tiny that it can rest on the end of your fingertip. Fascinatingly, it appears to be smaller than several known species of ants.
A group of researchers from the State University of Campinas in Brazil has recently identified a new species called Brachycephalus dacnis.
This flea tod is only 6.95 millimeters long. Another research group had previously discovered a different species within the same genus, B. pulex, located in Brazil’s southern state of Bahia. One of the specimens was measured at just 6.45 mm in length.
This represents the seventh species of flea toad identified within the genus Brachycephalus. The toad’s diminutive size is an adaptation suited to its distinctive habitat.
Flea toads are small adults, measuring under 1 cm. Their adult size is so diminutive that it is much smaller than an average human fingernail or a 50-cent coin.