A new study of an ancient bony fish has forced scientists to rethink how sharks evolved. The study, published in the journal Nature, found that the fish, called _Andreolepis hedei_, had a number of features that were previously thought to be unique to sharks. These features include a cartilaginous skeleton, a dorsal fin, and a tailfin with a lower lobe that is longer than the upper lobe.

The discovery of _Andreolepis hedei_ suggests that sharks and bony fish may have evolved from a common ancestor that had a cartilaginous skeleton and a dorsal fin. This ancestor may have lived in the oceans around 420 million years ago.

The discovery of _Andreolepis hedei_ also has implications for our understanding of the evolution of vertebrates. Vertebrates are animals that have a backbone, and they include fish, amphibians, reptiles, birds, and mammals. The discovery of _Andreolepis hedei_ suggests that the earliest vertebrates may have had a cartilaginous skeleton, rather than a bony skeleton.

The discovery of _Andreolepis hedei_ is a significant find that has forced scientists to rethink how sharks and bony fish evolved. The study also has implications for our understanding of the evolution of vertebrates.

Here are some of the key findings of the study:

* _Andreolepis hedei_ is an ancient bony fish that lived around 420 million years ago.

* _Andreolepis hedei_ had a number of features that were previously thought to be unique to sharks, including a cartilaginous skeleton, a dorsal fin, and a tailfin with a lower lobe that is longer than the upper lobe.

* The discovery of _Andreolepis hedei_ suggests that sharks and bony fish may have evolved from a common ancestor that had a cartilaginous skeleton and a dorsal fin.

* The discovery of _Andreolepis hedei_ also has implications for our understanding of the evolution of vertebrates, suggesting that the earliest vertebrates may have had a cartilaginous skeleton, rather than a bony skeleton.