Skinny shark

Ostenoselache (Ostenoselache stenosoma) is an extinct shark belonging to the Neoselacians. It lived in the Lower Jurassic (about 200 to 195 million years ago) and its fossil remains have been found in Italy. It was characterized by an unusually elongated rostrum.
This shark possessed a very distinctive body shape, very different from that of any current or extinct shark. The body was very slender (hence the nickname skinny shark informally given to it by scholars), and in total the animal could reach a maximum length of about 30 centimeters.
The spine consisted of about 150 spool-shaped vertebrae. The skull, although poorly preserved in most specimens, was very distinctive: the orbits were large, while the mandible was long and thin and equipped with about 30 simple, single cusped teeth.
The skull extended into an elongated and flattened rostrum, which projected well beyond the mouth; the rostrum was completely different from the structure found in animals such as sawfish, goblin sharks, or rays, and was formed by a cartilaginous skeleton with a complex structure, with a series of branches projected forward.
The fins are little known, but many specimens retain the additional cartilage that forms the pelvic appendage of males. The anus was located far forward, and the tail was very long.
Ostenoselache is the only shark to possess a single median fin, the anal, extending from the anus to the tip of the tail and supported by numerous radial cartilages.