Download Full Document - Mountain Boomer Music!

1996 McGUIRE-SYSTEMATICS OF CROTAPHYTID LIZARDS 2 1
- -
Fig. 13.-Lingual view of the right mandible of (A) Croraphyrus Fig. 14.-hbial view of the right mandible of (A) Crotaphytw
reticularus (REE 2912, adult male, SVL = 122 mm) and (B) rfliculallu (REE 291 2, adult male, SVL = 122 mm) and (B)
Gatnbclia cowi (REE 2800, adult female. SVL = 123 mm). Ang Gamhflia coppi (REE 2800, adult female, SVL = 123 mm). Cor
= angular, An - anicular. Cor = coronoid, Den = dentav, pmf = COronoid~ Den dcntav, PrC = preanicular, Sur = surangular.
=
= posterior mylohyoid foramen, Pre = preanicular, Spl = splenmm.
ial. Sur = surangular. Scalc = 5 mm.
completely encloses Meckel's cartilage. In crotaphytids,
the tubular nature of the dentary is incomplete.
The anterior end of the dentary is open, while
posteriorly the groove is closed, but not fused. In
Crotaphy~tu, with the exception of C. grismeri, the
groove is usually closed over less than one-half of
its length anterior to the splenial and there is relatively
consistent interspecific variation in this characteristic.
In C. collaris. C. nebrius. and C. reticulatus.
Meckel's groove is often open over its entire
length anterior to the splenial, and most of the remaining
specimens have the groove closed over less
than one-third of its length. In C. antiquus and C.
dickrsonae, the groove is not open over its entire
length, but as in the above-mentioned taxa, it was
nearly always closed over less than one-third of its
length. In C. bicinctores, C. insularis, and C. vestigiurn.
Meckel's groove is usually closed over between
one-third and one-half of its length anterior to the
splenial and was only once observed to be open over
its entire length (C, vestigittrn. REE 28 11). Crotaphytusgrismeri
is unique among Crotaphytus in that
Meckel's groove is closed over between approximately
50 percent and 70 percent of its length in all
specimens examined (five of five). Norell (1989)
noted that in Gambelia, the groove is usually closed
over two-thirds of its length anterior to the splenial.
Unfortunately, this condition is much more variable
in Garnbelia than in Crotaphytus. and although the
groove in most specimens is closed over greater than
one-half of its length anterior to the splenial, 12 of
30 G. silus, two of nine G. copei, and 12 of 45 G.
wislizenii had a condition similar to that observed
in Crotaphytus, with the groove closed over less than
half of its length anterior to the splenial. Because of
this variation, this character was not considered in
the phylogenetic analysis.
Norell (1 989) also considered an elongate dentary
(with a posterior process projecting posterior to the
superior apex of the coronoid, Etheridge and de
Queiroz, 1988) to be a synapomorphy for Crota-
phytidae. Although this character state was found
to be derived in their phylogenetic analysis of pleu-
rodont iguanians (possibly a paraphyletic assem-
blage with respect to acrodont iguanians [Chamae-
leonidae]), this state is widespread within Iguania
and may be a synapomorphy for a group more in-
clusive than Crotaphytidae.
The dentary bears between three and eight mental
foramina anteriorly. In Crotaphytus, the mental fo-
ramina are usually restricted to the distal end of the
dentary, while in Gambelia they may extend pos-
teriorly to the midpoint of the bone. Continuous
variation in this feature prevented its inclusion in
the phylogenetic analysis.
A trgular (Characters 23, 24; Fig. 1 3). -In Crota-
phytus, the exposed portion of the angular extends
further anteriorly than in Garnbelia wislizenii and
G. copei. Defining states for this character is com-
plicated by the variation that exists in those struc-
tures that may serve as reference points. For this
reason, two points of reference are included in the
description of this character. In adult Crotaphytus.
with very few exceptions, the angular extends an-
teriorly at least to the fourth tooth (counting from