Paleontologists Yara Haridy and Karma Nanglu are uncovering secrets about Earth’s earliest vertebrates. Unlike dinosaurs or ancient shells, their fossils – known as “fish flakes” – are tiny and hidden within rocks. To reveal these fossils, geologists dissolve the rock layers in acid.
The “fish flakes” were first discovered in Cambrian rocks, revealing a 20-million-year gap between the earliest squishy vertebrates and more advanced forms. Haridy hopes her research will fill this gap by finding a hypothetical vertebrate between the two stages.
Source: https://defector.com/the-tooth-hurty-joke-has-its-origins-in-ancient-armored-fish