Besanosaurus leptorhynchus

Besanosaurus leptorhynchus was an ichthyosaur that inhabited the seas of the Middle Triassic, approximately 240 million years ago, in what is now northern Italy. Fossils of this species were discovered in the Besano region, from which it takes its name, within the Besano Formation, a site known for its exceptional preservation of marine fossils. This species was formally described in 1996, and has since been the subject of studies due to its distinctive features among ichthyosaurs, a group of marine reptiles that exhibit remarkable evolutionary convergence with modern dolphins.

Besanosaurus leptorhynchus was a large-sized ichthyosaur, with estimates suggesting it could reach a length of up to 8 meters, making it one of the largest ichthyosaurs of its time. Its elongated, fusiform body was perfectly adapted for marine life. What sets it apart, however, is its long, narrow skull, which gave it a hydrodynamic appearance. Its snout, or rostrum, was noticeably elongated and thin, which is reflected in its name “leptorhynchus,” meaning “thin snout.” This trait indicates that Besanosaurus probably had a specialized way of life, hunting fast prey such as fish and cephalopods in shallow seas.

Its dentition was also peculiar. The teeth were small and sharp, perfect for catching slippery prey such as fish, and suggest that this ichthyosaur was not adapted for crushing or chewing, but for catching and swallowing its prey whole. Because of its size and shape, Besanosaurus is thought to have been an agile predator that hunted by ambush, using its speed and maneuverability to capture smaller aquatic animals.

Besanosaurus had a robust body, with pectoral fins and a tail that probably allowed it to move quickly and agilely through the water, using a swimming style similar to that of modern fish. However, unlike dolphins and other modern cetaceans, ichthyosaurs like Besanosaurus did not breathe underwater, so they had to come to the surface to obtain oxygen.

The environment in which Besanosaurus leptorhynchus lived was marine and tropical, since during the Triassic, warm seas covered large areas of what is now Europe. This ichthyosaur inhabited lagoons and shallow seas, coexisting with other forms of marine life, including other smaller ichthyosaurs, marine reptiles and a rich fauna of fish and cephalopods. The abundance of prey in these seas would have supported large predators like Besanosaurus.

The most recent studies on the fossils of Besanosaurus leptorhynchus have shed new light on its biology and evolution. Thanks to the excellent preservation of the fossils in the Besano Formation, it has been possible to study aspects of its internal anatomy and development. One of the most interesting findings is that some Besanosaurus fossils contain remains of embryos inside, indicating that, like other ichthyosaurs, this marine reptile was viviparous, that is, it gave birth to live young instead of laying eggs. This allowed it to spend its entire life in the water without the need to return to dry land.

Approximate measurements of Besanosaurus:

• 1:60 scale Complete
• Length 128 mm
• Height 54 mm
• Width 68 mm
• Snout-tail length 135 mm
  
  
• 1:35 scale Complete
• Length 220 mm
• Height 93 mm
• Width 116 mm
• Snout-tail length 230 mm