SCALING RELATIONSHIPS WITHIN THE MAXILLARY TOOTH ROW OF THE FELIDAE, AND THE ABSENCE OF THE 2ND UPPER PREMOLAR IN LYNX

Suggestions that short-faced members of the Felidae tend to lack the s econd upper premolar (P2) imply a possible shift in scaling associated with the palate and maxillary tooth row in Lynx, which lacks P2, as c ompared to felids that retain it. This hypothesis is tested using a sc aling model that relates the lengths of the palate, and the upper toot h row and its components, to post-palatal skull length in the small to moderately large felids Felis catus (domestic cat), L. canadensis (Ca nada lynx), F. pardalis (ocelot), and F. concolor (cougar). Scaling re lationships of both palate and tooth row length to post-palatal skull length do not differ significantly from isometry in all four species. However, ocelots have a significantly shorter palate and tooth row tha n lynxes over their overlapping ranges of post-palatal skull length, s uggesting that the absence of P2 is not correlated with the length of the face in these species. C1, P3 and P4 tend to be relatively longer in larger felids; none the less, ocelots have a relatively small P3 an d lynxes have a proportionately large P4. Because both lynxes and ocel ots have a relatively small gap between C1 and P3, the absence of P2 i s not correlated with available space within the tooth row in adults. However, lynxes also appear to have a relatively long dP3 that almost obliterates the diastema within the deciduous tooth row. The absence o f P2 in Lynx may be an engineering artefact that is associated with a shift in proportions within the deciduous toothrow, resulting in inhib ition of the development of P2 and dP2 early in ontogeny. Despite the variable occurrence and polymorphism associated with P2 in the Felidae , this character has systematic value within this clade and is a synap omorphy for Lynx.