Scientists Discover Huge Fossil Revealed to Be the World’s Oldest Tadpole, Leave Them Stunned
A fossil uncovered in Argentina has become the earliest known tadpole found by experts. The tadpole belongs to an ancient frog species called Notobatrachus degiustoi and is the only known larva specimen from this group, stated Science Alert. After seeing the size of the fossil, experts believe that the tadpole was close to its metamorphosis phase. The fossil has been calculated to be around 16 centimeters (or 6 inches) in length and was placed in a Jurassic-era rock within the La Matilde Formation. Findings regarding this fossil have been published in Nature.
According to examinations the tadpole moved around the earth some 160 million years ago. Hence, the fossil has surpassed the previous oldest tadpole by 20 million years. The remains of N.degiustoi were located on a slab of sandstone. The slab featured the amphibian's skull and backbone and also had remarkable impressions of its eyes and nerves. Researchers were astounded to witness the fossil in such a pristine condition. "The exquisite preservation of the new specimen, including most of the hyobranchial apparatus and soft tissues, allows us to infer the mode of life and feeding habits of the N. degiustoi tadpole," researchers wrote. "This finding substantially enhances our knowledge of the origins and early evolution of the biphasic anuran life cycle."
The remains of N.degiustoi are very similar in features to modern-day tadpoles. The creature appears to have a gill scaffold system which is used by their present-day counterparts to filter food particles from water. Experts believe this implies that throughout their evolution, the mechanisms employed by tadpoles to survive have remained more or less the same. The mechanisms seemed to have worked brilliantly as the group managed to outlast several mass extinctions throughout the centuries, according to The Guardian.
Experts always suspected that the most pivotal steps in tadpole evolution happened with stem anurans just during the Triassic and Jurassic periods. Stem anurans have been identified as the evolutionary predecessors of modern frogs and toads. The speculation was rooted in findings from modern-day amphibians. This was because no tadpole fossils from these particular periods had been located by researchers until now.
"This finding has dual importance because it represents the oldest-known tadpole and, to our knowledge, the first stem-anuran larva," the authors stated in the study, according to Science Alert. "Its exquisite preservation, including soft tissues, shows features associated with the filter-feeding mechanism characteristic of extant tadpoles. Notably, both N. degiustoi tadpole and adult reached a large size, demonstrating that tadpole gigantism occurred among stem-anurans."
Experts already know that frogs inhabited the planet some 217 million years ago. However, their evolution journey, especially when they transformed from tadpoles to frogs remains a mystery. Experts believe such discoveries will give clarity on that aspect. "It’s starting to help narrow the timeframe in which a frog becomes a frog," said Ben Kligman, a paleontologist at the Smithsonian National Museum of Natural History who was not involved with the research, as per The Guardian.