Spinemuus

Spinemuus is a genus of extinct mammals that lived during the Late Cretaceous period, approximately 72 to 66 million years ago. The genus is known from a single species, Spinemuus spinosus, which was discovered in the Hell Creek Formation of North Dakota, USA. Spinemuus is notable for its distinctive skull structure, which features a large, bony crest that runs along the top of the skull, giving the animal its name, which translates to "spiny mouse."

Spinemuus was a small mammal, with an estimated body length of around 15 centimeters. It had a relatively long snout and small eyes, suggesting that it may have been a nocturnal or crepuscular animal. The animal's teeth were adapted for a diet of insects and small vertebrates, and it likely used its sharp claws to catch prey.

The discovery of Spinemuus has provided valuable insights into the evolution of mammals during the Late Cretaceous, a time when mammals were still relatively small and diverse. The animal's skull structure is unique among mammals, and its discovery has helped to shed light on the diversity of mammal skulls during this period.

Spinemuus is an important fossil find, as it provides evidence of the early evolution of mammals and their adaptations to different environments. The animal's discovery has also helped to fill in gaps in our understanding of the diversity of mammals during the Late Cretaceous, a time when mammals were still evolving and adapting to new ecological niches.