Diagnosis:
The outer face of the type specimen shows
no part of the coronoid but the scar of attachment is indicated by a
slightly depressed area, extending forward to the middle of the
fourth tooth (from last). Below the diastema between the eighth
and ninth teeth (from last) is a forward-directed foramen, which
is situated above the level of the middle of the dentary. The region
toward the ventral surface, lying below the fifth to eighth teeth, is
smooth, lacking any distinct striation or rugosity. On the inner
face of the dentary the Meckelian groove, which is lateral (but becoming ventral anteriorly), and the Meckelian cavity are completely exposed, owing to the absence of the thin splenial, which
covers the groove.
The teeth are pleurodont and unequally bilobed, the small lobe
being anterior. The second, fourth, and fifth teeth (from last)
show a very faint trace of a still smaller posterior notch or lobe,
which is a counterpart of the third lobe, present in certain living
species of Aspidoscelis; The teeth are wider in proportion to
length when compared with modern representatives of Aspidoscelis living in this southwestern region, and the crowns seem
more blunt, but the latter difference may be due to age and wear.
The relative size of the teeth and their characters are shown in
figure 1 (of Taylor, 1941).
The jaw of this extinct species has been compared with the jaws
of the living Aspidoscelis sexlineata (Linne), A. perplexa
Baird and Girard, A. gularis Baird and Girard, and A. melanostetha Cope. Actually, the only one of these species known in this
territory today is A. sexlineatus. This form agrees in the normal
absence of distinctly trilobed teeth, but differs in having more
slender and somewhat more tapering, laterally compressed teeth.
The bases are proportionally closer together and the upper parts are somewhat more widely separated. In A. gularis, living in
Texas, the four or five posterior teeth are generally trilobed, the
posterior lobe being nearly as distinct as the anterior. The posterior teeth of A. melanostetha are more like those of A. sexlineata, and the outer posterior face of the dentary is very definitely
sculptured and somewhat rugose. A. perplexa has teeth that are
heavier on the basal portions, and the posterior part of the dentary
is smooth. Also, the anterior extension of the coronoid is shorter,
reaching forward only to the level of the third tooth, and it is more
pointed. The teeth taper more towards their tips and their bases
are closer together than in the described new species.
Measurements of the type specimen in millimeters, are as follows: extreme length of fragment figured, 7; elevation of dentary
at posterior lateral foramen, 1.8.