Trapped in a fossil, this extinct fish (Gogo arthodires, which inhabited the planet before the dinosaurs) was discovered in the Gogo Formation, an ancient coral that is now a repository of fossils of this extinct animal. “Evolution is often thought of as a sequence of small steps, but these fossils suggest there was a bigger jump between jawless and jawed vertebrates. [os Gogo] literally have their hearts in their mouths and under their gills – just like sharks do today,” says Kate Trinajstic, researcher at Curtin University (Australia) and lead research published in the scientific journal Science.
Gogo fish are the first of a class of prehistoric fish called placoderms. They were the first fish to have jaws and teeth. Before them, fish measured no more than 30 cm, but placoderms could be up to nine meters long. Placoderms were the dominant life form on the planet 100 million years before the existence of the first dinosaurs. Typically, it is bones, not soft tissues, that are turned into fossils – but at this Kimberley site, minerals have preserved many of the fish’s internal organs, including the liver, stomach, intestine and the heart.
“We were able to see, for the first time, all the organs together of a primitive fish with a jaw, and we were especially surprised to learn that they were not so different from us”, says the researcher, in a press release.
From the 380 million year old core and its location, scientists can better understand the process of evolution on Earth. For example, it is interesting to see how the head and neck region began to change to accommodate the jaws, a critical step in the evolutionary process that affects humans and other species.