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Description

A selection of the basal feliform carnivorans known as nimravids, to scale.

What looks like a cat, hunts like a cat, but isn't actually a cat? There have been a number of mammalian groups which have followed a similar path to felids in shape, form and behaviour. Several examples have been covered in previous posts, such as Pseudo-felids (sort of) - Oxyaenids and one particular famous species in Pouched predators 1 - Borhyaenoids . Thylacoleonids were another group of cat-like marsupials. These three examples are quite distantly related to cats, but even within the carnivorans there have been cat analogues. Madagascan fossa are the closest of the living species, but there were two other groups in the past. Nimravids and barbourofelids were previously grouped together (but are now separated into different families) and show remarkable convergence with felids. It is the former of these two groups which are the subject of this post.

Carnivorans are split into two main groupings: the cat line (Feliformia) and the dog line (Caniformia). Besides true felids, the feliforms include families which have obvious similarities to cats, such as civets, but also those that are decidely uncat-like (hyenas and mongooses). Nimravids were an early off-shoot which filled the vacant role of large ambush-hunters during the Eocene and Oligocene. There is some variation within the group: early species having shorter canines and longer limbs, while the better known later species were imitated later on by the famous sabretooth machairodont cats (see The Last Sabretooths - Machairodont Felids ). The sabreteeth were rounded in cross-section and protected by bony sheaths on the lower jaw when the mouth was closed. Short powerful legs would wrestle down and hold prey while the teeth were employed. Nimravids were evidently terrestrial hunters, having short feet and they walked either in a plantigrade or semiplantigrade posture.

Differences in dentition altered the way nimravids hunted. The long lived Dinictis had shorter thicker canines which were capable of delivering a greater puncture bite compared to other nimravids. Several Hoplophoneus specimens have been found with damage caused by conspecifics usually aimed towards the back of the skull and the orbits, and this may give a clue to how the longer toothed nimravids dispatched prey. Although only known from limited remains, the giant among the nimravids was Quercylurus weighing in at about 200 kg. How Quercylurus hunted is still unknown. Juvenile nimravids were largely dependent on adults to provide food, in much the same manner as machairodont cats. Sabreteeth erupt late and the dediduous teeth were not suitable for killing prey. This has potential implications on the socialiabity of nimravids.

Nimravids enjoyed a warm Late Eocene climate that was trending towards a cooler drier environment into the Oligocene. As woodland was replaced by more open grassland, slower predators like nimravids were unable to keep pace with the fleeter footed prey and they died out before the Miocene.

Description

A selection of the basal feliform carnivorans known as nimravids, to scale.

What looks like a cat, hunts like a cat, but isn't actually a cat? There have been a number of mammalian groups which have followed a similar path to felids in shape, form and behaviour. Several examples have been covered in previous posts, such as Pseudo-felids (sort of) - Oxyaenids and one particular famous species in Pouched predators 1 - Borhyaenoids . Thylacoleonids were another group of cat-like marsupials. These three examples are quite distantly related to cats, but even within the carnivorans there have been cat analogues. Madagascan fossa are the closest of the living species, but there were two other groups in the past. Nimravids and barbourofelids were previously grouped together (but are now separated into different families) and show remarkable convergence with felids. It is the former of these two groups which are the subject of this post.

Carnivorans are split into two main groupings: the cat line (Feliformia) and the dog line (Caniformia). Besides true felids, the feliforms include families which have obvious similarities to cats, such as civets, but also those that are decidely uncat-like (hyenas and mongooses). Nimravids were an early off-shoot which filled the vacant role of large ambush-hunters during the Eocene and Oligocene. There is some variation within the group: early species having shorter canines and longer limbs, while the better known later species were imitated later on by the famous sabretooth machairodont cats (see The Last Sabretooths - Machairodont Felids ). The sabreteeth were rounded in cross-section and protected by bony sheaths on the lower jaw when the mouth was closed. Short powerful legs would wrestle down and hold prey while the teeth were employed. Nimravids were evidently terrestrial hunters, having short feet and they walked either in a plantigrade or semiplantigrade posture.

Differences in dentition altered the way nimravids hunted. The long lived Dinictis had shorter thicker canines which were capable of delivering a greater puncture bite compared to other nimravids. Several Hoplophoneus specimens have been found with damage caused by conspecifics usually aimed towards the back of the skull and the orbits, and this may give a clue to how the longer toothed nimravids dispatched prey. Although only known from limited remains, the giant among the nimravids was Quercylurus weighing in at about 200 kg. How Quercylurus hunted is still unknown. Juvenile nimravids were largely dependent on adults to provide food, in much the same manner as machairodont cats. Sabreteeth erupt late and the dediduous teeth were not suitable for killing prey. This has potential implications on the socialiabity of nimravids.

Nimravids enjoyed a warm Late Eocene climate that was trending towards a cooler drier environment into the Oligocene. As woodland was replaced by more open grassland, slower predators like nimravids were unable to keep pace with the fleeter footed prey and they died out before the Miocene.