The first cat-like saber-tooth predator was discovered in 1879 by the famous American paleontologist Othniel Charles Marsh. The discovery took place in the Bridger Basin of Wyoming, United States, where Marsh's team was conducting extensive excavations of Eocene-era fossils.

The specimen that Marsh discovered was a partial skull of a small, primitive carnivore that he initially named Dinictis felina. Dinictis means "terrible weasel," referring to its small size and long, slender body, while felina means "cat-like" due to its resemblance to modern cats. Further studies and more complete specimens later confirmed Dinictis as the earliest known member of the saber-tooth cat family, Felidae.

Here are the key aspects of Dinictis felina and how it differs from modern cats:

1. Appearance and Size: Dinictis felina was a small predator, weighing approximately 10 to 15 kilograms (22 to 33 pounds). It had a long, slender body, similar to a weasel or marten. Its overall appearance was more like a small cat or civet than a modern saber-tooth cat.

2. Dental Features: What made Dinictis unique and earned it the title of "cat-like saber-tooth predator" were its distinctive teeth. Its upper canines were elongated, but they were not as long or curved as in later saber-tooth cats like Smilodon. Dinictis's canines were more similar in shape to those of modern cats, albeit larger and more pointed. This suggests that Dinictis was transitioning from the typical cat-like teeth to the specialized saber-tooth morphology.

3. Hunting Adaptations: Dinictis's saber-like canines were likely used for capturing and killing small to medium-sized prey, such as rodents, rabbits, and possibly small ungulates. Although not as specialized as later saber-tooth predators, Dinictis represented an early stage in the evolution of the saber-tooth hunting strategy.

4. Evolutionary Significance: Dinictis felina holds great significance in understanding the evolution of saber-tooth cats and their relationship to modern cats. It bridges the gap between early cat-like predators and more specialized saber-tooth species like Smilodon. By studying Dinictis, paleontologists have gained insights into the gradual changes in dental adaptations and hunting behaviors that occurred during the evolution of this remarkable group of predators.

In summary, the discovery of Dinictis felina in the late 19th century provided evidence of an early, cat-like saber-tooth predator that differed from modern cats in terms of size, dental features, and hunting adaptations. It offers a glimpse into the evolutionary journey of saber-tooth cats and highlights their unique place in the history of carnivorous mammals.