Falcatus falcatus-Male-Montana-BG85

 Taxa: Falcatus falcatus

Age: Carboniferous-Mississippian

Geology: Heath Limestone-Bear Gulch Member

Locality: Fergus County, Montana

Falcatus falcatus

Falcatus falcatus is an extinct species of early cartilaginous fish, dating back to the Carboniferous period, about 340 million years ago.

F. falcatus was a small, shark-like fish, usually around 25-30 centimeters (about 10-12 inches) in length. It had a streamlined body typical of a predator, with a heterocercal tail (the upper lobe is longer than the lower lobe) aiding in its swimming agility.

F. falcatus displays sexual dimorphism with one of its most distinctive features. The males had a large, curved spine or "sword" projecting from the top of its head. This spine is thought to have been used for display or possibly as a weapon in intraspecies competition.

Fossils of Falcatus falcatus provide valuable insights into the evolution of early cartilaginous fishes, showing an array of unique adaptations and ecological roles in ancient marine ecosystems.

 Bear Gulch Limestone

The Bear Gulch Limestone is a fossil-rich geological formation located in Montana, USA, known for its exceptional preservation of marine fossils from the Mississippian subperiod of the Carboniferous period, approximately 330 million years ago.