Neither Hyenas nor Cats, Nimravid Family, an ancient carnivore group, preceded both. Flourishing during the Oligocene epoch (34 million years ago (mya) to 21 mya), Nimravids roamed throughout Eurasia and North America. Known as “False Saber-toothed Cats”, They are an example of parallel evolution.
Only paleontologists can tell the skulls of Nimravids and Saber-toothed Cats apart. Nimravids had similar life styles to these Cats such as seizing their prey with their claws. In addition, Nimvarids had saber teeth like many Cats. Because of these characteristics, at one time They were included in the Cat Family. Now, Nimravids are considered a separate group of carnivores.
Nimravids point to the diversity of life. They first appeared in the late Eocene epoch (37 mya). Living in the woodlands, They survived until nine mya (the late Miocene). Only when the forests became grasslands did Nimravids become extinct. (During this time, Cats emerged as well as Hyenas.)
Saber-toothed design for carnivores is more common than most people know. The Gorgonopsids of the Permian Period (290 – 248 mya) were the first to have it. Then during the Eocene epoch, Creodonts (ancient carnivores) developed saber teeth. Moreover, Barbourofelids (close relatives to Cats) and Thylacosmilidae (marsupials from South America) also had them. What this means is that saber teeth alone do not a Cat make. It takes more.
Nimravids take you back into the murkiness of time. What you may think is so, may not be. Allow your doubts to surface, and be ambivalent as you ponder your sureties. Asking questions will lead you onto paths of new discoveries. Question first instructs Nimravids, before you decide.