cladogram: This is a manually constructed cladogram that I use when teaching. It demonstrates the three major clades, or divisions of living families within the order Carnivora. In blue is the large and diverse group known as the arctoids. The canids (dogs, wolves, coyotes, etc,) are represented by a single lineage in green. The cats, hyenas, mongoose and viverrids are the red group known as the aeluroids. Characters 1, 2, and 3 are hypothesized to unite all of Carnivora:
Character 1 is use of the upper fourth premolar (P4) and lower first molar (m1) by all members of the order Carnivora to eat meat. This is called the P4/m1 carnassial apparatus.
Character 2 is near and dear to all veterinarians who practice on dogs and cats. Character 2 is the presence of anal sacs. Anal sacs are hypothesized to be present in the ancestor of Carnivora due to its widespread distribution among all of the living members. Anal sacs are lost or reduced only in bears and in the aquatic families (seals, sea lions, walrus and otters).
Character 3 is the primitive carnivoran dentition: 4 premolars and 3 molars in both the upper and lower dentition.
Character 4 unites all of the living families of Carnivora. Character 4 is the development of an ossified bulla covering the middle ear, a bony covering for the ear apparatus. The primitive carnivorans (carnivoran = member of the order Carnivora) had a single-chambered bulla covered by cartilage.
Character 6 diagnoses the four closely related families referred to as the aeluroids or the sub-order Aeluroidea. Character 6 is a modification of the primitive single-chambered bulla: the development of a two-chambered bulla. Evidence of character 6 can be seen in the
ventral skull
and in the
basicranial photograph
Data Table Results: There are arguments for and against sexual dimorphism being the explanation for some character differences between species of fossil felids. Arguments for include: (1) Sexual dimorphism is seen in modern felid species, at the very least in body size and skull length in small felids. (2) The fossil felids Pseudaelurus skinneri and Pseudaelurus stouti display differences in c--p3 length that could also be interpreted as sexual dimorphism. (3) The fossil felids Pseudaelurus intrepidus and Pseudaelurus marshi are size and temporally equivalent. Specimens of the two species are sometimes found in the same paleontological localities (quarries). Arguments against include: (1) A similar range in c--p3 length and dentary height and width is not seen in the fossil felid Pseudaelurus validus. Pseudaelurus validus and some modern species do not exhibit sexual dimorphism in the lower jaw. (2) Modern assemblages of felids sometimes contain at least two species that are indistinguishable in jaw length. (3) The p error for the hypothetical Pseudaelurus intrepidus--Pseudaelurus marshi (male-female) species that I created in this tab le (0.0001) is far outside the range of p error seen in the four modern species studied (0.28--0.008). The results appear inconclusive, due primarily to the variability of the sexual dimorphism displayed by different species of living felids. However, if Pseudaelurus intrepidus and Pseudaelurus marshi were indeed sexually dimorphic members of the same species, the males and females differed far more than any of the four living felids that I studied.
Stratigraphic Chart: This is a rough estimate of stratigraphic ranges for various fossil felids. As new specimens are discovered, or as fossil localities are dated more precisely, these ranges will change. The first North American felids arrived during a major dispersal from Eurasia to North America that began approximately 20 m.y. ago. The early fossil felid record of Asia is poor. Only a small number of specimens have been recovered from early and middle Miocene localities. Therefore, the stratigraphic range of Pseudaelurus in Asia is less certain than Europe and North America.
My present felid research project is a study of the early North American saber-tooth cats, often referred to as the machairodont felids. Nimravides and Machairodus are two of the earliest North American saber-tooth cats. NA Felis refers to the stratigraphic range of fossils of the modern felids.
