Published today, our new paper describes a spectacular 400 million-year-old 3-D-preserved fossil fish, Ligulalepis.
The 3-D anatomy of the fossilised Ligulalepis skull reveals previously unknown details of the pattern of dermal skull bones, the shape of the brain cavity, and other soft tissue features (such as nerves and blood vessels) in this species.
Why are we so excited about discovering the structure of an ancient fish skull? Because Ligulalepis sits in a very important position in the vertebrate evolutionary tree.
Boney fishes—and us
Fishes are the most diverse group of backboned animals (vertebrates) on the planet, with roughly 30,000 known species.
The vast majority of these (around 98%!) are bony fishes or osteichthyans. These includes most of fishes we like to eat, such as salmon, tuna and trout, as well as fishes we keep as pets, like goldfishes and guppies. These are called ray-finned fishes (actinopterygians) as their fins are supported by bony rods called fin-rays.
The other major group of bony fishes have robust lobe-fins (sarcopterygians), a group that contains the living lungfishes and coelacanths, as well as several extinct groups.
Sarcopterygians are an important group because the first four-legged land animals, the tetrapods, evolved from them. Today we can regard all living tetrapods (amphibians, reptiles, birds and mammals) as a subgroup within the bony fishes.
An exciting new find
The first discovery of the fish called Ligulalepis was a tiny fossil fish skull found in limestone near Wee Jasper in New South Wales about 20 years ago.
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