Nimravidae

Nimravids (false sabre-tooths) Fossil range: 37–5 Ma PreЄ Є O S D C P T J K Pg N Early Eocene - Late Miocene
Hoplophoneus mentalis
Conservation status
Fossil
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Suborder: Feliformia Family: †Nimravidae
Subfamilies
†Nimravinae †Hoplophoninae

Nimravidae cladogram

The Nimravidae, sometimes known as false sabre-tooths, are an extinct family of mammalian carnivores belonging to the suborder Feliformia and endemic to North America, Europe, and Asia living from the Eocene through the Miocene epochs (42—7.2 mya), existing for approximately 34.8 million years.^[1]

Morphology

Although some nimravids physically resembled the sabre-toothed cats of genus Smilodon, they were not closely related, but evolved a similar form through parallel evolution. Previously classified as a subfamily of Nimravidae, the barbourofelids have been recently reassigned to their own distinct family Barbourofelidae (Morlo et al. 2004).^[2]

The ancestors of nimravids and felids diverged from their common ancestor, from the Caniformia-Feliformia split, in the middle Eocene about 50 million years ago (mya), with a minimum constraint of 43 mya. Recognizable nimravid fossils date from the late Eocene (37 mya), from the Chadronian White River Formation at Flagstaff Rim, Wyoming, to the late Miocene (5 mya). Nimravid diversity appears to have peaked about 28 mya. Most had muscular, low-slung, catlike bodies, with shorter legs and tails than typical of cats.

Taxonomy

Nimravidae was named by Cope (1880). Its type is Nimravus. It was assigned to Fissipedia by Cope (1889); to Caniformia by Flynn and Galiano (1982); to Aeluroidea by Carroll (1988); to Feliformia by Bryant (1991); and to Carnivoramorpha; by Wesley-Hunt and Werdelin (2005).^[3][4]

Nimravids are placed in tribes by some authors to reflect closer relationships in genera within the family. Some nimravids did evolve into large toothed cat-like forms with massive flattened upper canines and accompanying mandibular flanges. Others had dentition similar to felids, or modern cats, with smaller canines. Others had moderately increased canines in a more intermediate relationship between the saber-toothed cats and felids. The upper canines were not only shorter, but also more conical, than those of the true saber-toothed cats. These are referred to as being False sabre-tooths.

Not only did nimravids exhibit diverse dentition but they also showed the same diversity in size and morphology as felids. Some were leopard-sized, others the size of today's lions and tigers, and one had the short face, rounded skull and smaller canines of the modern cheetah.

The skull of Hoplophoneus mentalis, showing the sabre-like teeth

Classification

• Family: Nimravidae
  • Subfamily Nimravinae
    • Genus: Dinictis
      • Dinictis cyclops
      • Dinictis felina
      • Dinictis priseus
      • Dinictis squalidens
    • Genus: Dinaelurus
      • Dinaelurus crassus
    • Genus: Dinailurictis
      • Dinailurictis bonali
    • Genus: Eofelis
    • Genus: Nimravus
      • Nimravus altidens
      • Nimravus brachyops
      • Nimravus edwardsi
      • Nimravus gomphodus
      • Nimravus intermedius
      • Nimravus sectator
    • Genus: Pogonodon
      • Pogonodon davisi
      • Pogonodon platycopis
    • Genus: Quercylurus
      • Quercylurus major
  • Subfamily Hoplophoninae
    • Genus: Eusmilis
      • Eusmilis bidentatus
      • Eusmilis cerebralis
      • Eusmilis sicarius
    • Genus: Hoplophoneus
      • Hoplophoneus belli
      • Hoplophoneus dakotensis
      • Hoplophoneus occidentalis
      • Hoplophoneus latidens
      • Hoplophoneus mentalis
      • Hoplophoneus primaevus
      • Hoplophoneus robustus

References

• Zoological Journal of the Linnean Society, 2003, 138, 477–493
• A new species of Prosansanosmilus: implications for the systematic relationships of the family Barbourofelidae new rank (Carnivora, Mammalia)

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