13. Parallel development of species is noted between _Dipodomys_ of the parental center and _Dipodomys_ of the isolated valleys of central California; _Dipodomys_ in the California center is the less specialized. 14. The trend of the dipodomyines, as indicated by the fossil record, has been toward a saltatorial specialization with consequent morphological changes. 15. The morphological change in the direction of saltatorial specialization is clearly evident in the compacting and aligning of the viscera as well as in the lengthening of the distal segments of the hind legs and the tail, tufting of the tail, enlargement of the auditory bullae, shortening of the neck and fusion of the cervical vertebrae for stability and other modifications of the skeleton. TABLE 7 MEASUREMENTS (IN MILLIMETERS) OF DIPODOMYS ORDII Key: A Total length B Length of tail C Length of hind foot D Greatest length of skull E Greatest breadth across bullae F Breadth across maxillary arches G Width of rostrum H Length of nasals I Least interorbital width J Basilar length =================+=====+=====+====+====+====+====+===+====+====+==== | A | B | C | D | E | F | G | H | I | J -----------------+-----+-----+----+----+----+----+---+----+----+---- _D. o. richardsoni_ 1-1/2 mi. N Beaver, Oklahoma (KU) [M] Mean (4) |251.2|131.5|40.5|41.0|24.7|22.0|4.3|14.9|13.0|26.3 Maximum |256 |136 |41 |41.8|25.1|22.3|4.5|15.4|13.2|27.3 Minimum |243 |133 |40 |40.4|24.4|21.5|4.2|14.6|12.7|26.0 | | | | | | | | | | [F] KU 17962 |253 |135 |42 |40.6|25.4|22.6|4.6|15.1|14.2|25.7 KU 17963 |246 |133 |40 |39.4|24.0| ...|4.3|14.1|12.5|25.6 KU 17964 |255 |136 |41 |41.2|25.5|22.1|4.5|15.1|13.8|26.2 -----------------+-----+-----+----+----+----+----+---+----+----+---- _D. o. oklahomae_ 2-1/4 mi. S Norman, Oklahoma (USBS) [M] Mean (4) |239.7|130.0|39.5|39.0|23.9|21.5|4.3|13.7|13.3|24.9 Maximum |254 |140 |42 |40.3|24.6|22.4|4.4|14.3|13.6|25.8 Minimum |227 |125 |37 |38.0|23.0|20.9|4.2|13.4|12.8|23.9 | | | | | | | | | | [F] USBS 265456|245 |133 |40 |39.1|24.5|22.0|4.4|14.4|13.5|25.3 OU 20140 |234 |120 |39 |38.7|23.8|21.7|4.4|14.3|13.5|24.8 -----------------+-----+-----+----+----+----+----+---+----+----+---- _D. o. compactus_ 19 mi. S Port Aransas, Mustang Island, Texas (TCWC) [M] Mean (10) |234.6|119.5|39.3|37.0|21.8|19.4|4.1|13.8|11.9|24.2 Maximum |251 |134 |41 |37.9|22.5|20.8|4.2|14.6|12.3|25.3 Minimum |228 |112 |38 |35.6|21.3|18.2|3.9|12.9|11.6|22.8 | | | | | | | | | |