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By Bridget Fahey and Phil Myers
Felids are perhaps the most specialized hunters of the carnivores, relying almost exclusively on prey that they have killed themselves. Their distribution includes every continent except for Australia and Antarctica, with the exception of the domestic cat which has now been transported to just about everywhere humans have gone. Cats are also not native to the island of Madagascar. Felids use a diversity of habitats, from desert to forest to mountain.
Physical features characterizing felids are a short 
rostrum, a vestigial or absent baculum, and retractable claws. Distal segments of digits in the relaxed position are pulled back and up into a sheath by an elastic segment, which prevents claws from getting blunt. The cheetah is an exception; it cannot retract its claws, and when attacking it tends to bowl over prey much like many canids. Cats have five toes on their forefeet and four on their hindfeet. They are digitigrade, and their metapodials are moderately long but never fused.
Besides having a short rostrum, the skulls of cats have bullae that are large and divided by a septum; no alisphenoid canal, and paroccipital processes flattened against the bullae.
Dentition is reduced in felids; shortening the jaw results in increased force at the bite point. The dental formula is 3/3, 1/1, 2-3/2, 1/1 = 28-30. The incisors are small and chisel-like. The canines vary from medium-sized to enormous in the extinct sabertooth cats. The upper canine is larger than the lower. The first premolar is absent; the second, when present, is atrophied. The molar is small and simple in structure. Carnassials are very well developed and cheek teeth are exclusively of the shearing type; cats do not crush or grind their food.
The hunting method of felids consists of a preliminary stalk followed by a final quick rush. Cats aim for the neck and usually sever the cervical vertebrae with their sharp, pointed canines. They rely on their sense of sight; their eyes are relatively large compared to other carnivores. They also have well-developed senses of smell and hearing, and at close range, their long whiskers provide an acute sense of touch.
Felids are usually solitary. An exception is the African lion, which forms prides centered around maternal descent. Males fight with each other for acceptance into these prides. The size of a lion pride is determined by resource availability. Lion females hunt cooperatively for the whole pride. Males are the main defenders of territories, keeping out foreign males and females. Males are driven from their natal prides at around three years of age and often spend time as nomads before they are able to defend their own pride.
The fossil record of the Felidae extends to the Late Eocene. No description of fossil felids is complete without some mention of the sabretooth cats. In these forms (and there were a number of species in at least two lineages of feloids involved), the upper canines elongate tremendously to form stabbing, sabre-like weapons. These teeth curve backward, flatten to become triangular in cross section, and sometimes develope a serrated edge. It seems clear that they are adaptations for stabbing prey, but exactly how they were used remains a mystery.
Two species of felids in Michigan, bobcat ( Lynx rufus) and lynx ( Lynx canadensis), can be distinguished by the shape of their presphenoid and the openings to hypoglossal and jugular foramina in the base of the cranium.
Literature and references cited
Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.
Paradiso, J. L. 1975. Walker's Mammals of the World, Third Edition. Johns Hopkins University Press, Baltimore.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution, an Illustrated Guide. Facts of File Publications, New York. 259 pp.
Stains, H. J. 1984. Carnivores. Pp. 491-521 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vii+576 pp.
Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
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Contributors
Bridget Fahey (author), University of Michigan. Phil Myers (author), Museum of Zoology, University of Michigan.
