Download Full Document - Mountain Boomer Music!

Recommendations

Info

1996 McGUIRE-SYSTEMATICS OF CROTAPHYTID LIZARDS 2 9 tomic fracture planes, including the hoplocercid Ho- plocercus, the phrynosomatid Phrynosoma, some tropidurids of the genus Tropidurus, the polychrotids Phenacosaurus, Chamaeleolis, Leiosaurus, Po- lychncs, Crrostrophus, Anisolepis, Chamaelinorops, and some Enyalius and Anolis, the corytophanids Corytophanes and Laemanctus, the iguanids Iguana delicatissima, Conolophus, A mblyrhynchus, and Brachylophus, and all chamaeleonids except occa- sional Uromastyx (Etheridge, 1967; de Queiroz, 1987; Frost and Etheridge, 1989; R. Etheridge, per- sonal communication, 1993). Thus, it is most par- simonious to assume that autotomic fracture planes were present in the common ancestors of the families Opluridae, Hoplocercidae, Iguanidae, Phry- nosomatidae, and Tropiduridae, given the phylogenetic relationships that have been proposed for these groups (Etheridge and de Queiroz, 1988; Frost and Etheridge, 1989; Norell and de Queiroz, 199 1 ; Frost, 1992). The polarity of this character is equiv- ocal for Corytophanidae and Polychrotidae (given the relationships proposed by Frost and Etheridge, 1989). The absence of fracture planes is known to be the ancestral condition only with respect to the family Chamaeleonidae. Although this character cannot be unequivocally polarized given the outgroup uncertainties, I have tentatively coded the absence of autotomic fracture planes as the derived state. Etheridge (1 967) mentioned that iguanians with the autotomic version of the type one iguanid (senso lato) vertebral pattern (vertebrae with single transverse processes and fracture planes, when present, that pass posterior to the transverse process), of which Gambelia is an example, usually have between five and 15 nonautotomic vertebrae that pre- cede the first autotomic vertebra. Gambelia generally fits this pattern with the first fracture plane oc- curring in G. wislizenii somewhere between the 14th and 22nd vertebrae, in G. copei between the 18th and 2 1 st vertebrae, and in G. silus between the 1 3th and 15th vertebrae. Ribs (Character 4 1). -Crotaphytids are charac- terized by a generally plesiomorphic complement of ribs, although phylogenetically informative variation is present. As in other iguanians, most of the ribs have a bony dorsal portion and a cartilaginous ventral portion, the inscriptional rib, that may either connect the bony portion with the sternum or xiphisternum or end free. The first rib-bearing cervical vertebra is usually the fourth, although the third vertebra supports ribs in numerous individuals, and in a few, the second vertebra supports ribs. Thus, there are usually five cemical ribs, although six or seven are not uncommon. The cervical ribs are followed by four sternal ribs that connect the vertebral column to the posterolateral border of the sternum (only three sternal ribs present in one of four C. antiquus). The sternal ribs are followed by either one (Gambelia) or two (Crotaphytus) xiphisternal ribs that connect the vertebral column with the xiphisternum. Finally, there may be a series of post- xiphisternal ribs that end freely. The ribs rapidly decrease in length posteriorly to a width roughly equal to that of the sacral pleuropophyses. The ter- minal presacral ribs are often smaller than those immediately anterior to them and are very rarely fused to the vertebra. Three xiphisternal patterns were observed and two of these appear to be quite consistent. Crotaphytus has a pattern of two xiphisternal ribs with an oc- casional free xiphisternal rod. Gambelia have just one xiphisternal rib and one free xiphisternal rod that curves anteromedially. Variation was observed in two specimens of Crotaphytus (C. bicinctores, REE 2934; C. collaris, REE 2948) and two specimens of Gambelia (G. silus, CAS 22742; G. wislizenii, REE 29 18). Both Crotaphytus specimens had the condition characteristic of Gambelia, although REE 2934 varied on one side only. The apparently anom- alous specimens of G. silus and G. wislizenii had two xiphisternal ribs plus a free xiphisternal rod, a condition observed infrequently in Crotaphytus. Etheridge (1 959) found two xiphisternal ribs to be present in oplurids, corytophanids, iguanids, hoplocercids, polychrotids, tropidurids (with the excep- tion of Phymaturus and Uracentron), and phrynosomatids (except Phrynosoma,, which have no xiphisternal ribs, and Callisauw,, with three). Frost (1992) listed several additional species of Tropi- durus and one Microlophus with three xiphisternal ribs. In chamaeleonids exclusive ofchamaeleonines, one xiphisternal rib is the common condition and is present in the presumably basal lineages of aga- minae (Physignathus, Hydrosaurus), while the absence of xiphisternal ribs were characteristic of Uro- mastyx and Leiolepis (Moody, 1980). In the few chamaeleonines that I have examined (Chamaeleo senegalensis, C. johnstoni), two xiphisternal ribs were present, although variation within chamaeleonines seems likely. Because two xiphisternal ribs is clearly the ancestral condition in all of the iguanian families
BULLETIN CARNEGIE MUSEUM OF NATURAL HISTORY NO. 32 except Chamaeleonidae, the presence of two xiphisternal ribs is assumed to be the ancestral state within Crotaphytidae. Therefore, two xiphisternal ribs was coded as state 0 and that of a single xiphisternal rib as state 1. The shape of the xiphisternal rod of Gambelia is similar to that described in Tropidunls semitaen- iarus (Frost, 1992) in that the free end of the cartilaginous rod curves anteromedially, crossing su- perficially to the xiphisternal rib and posteriormost sternal ribs. The posterior xiphisternal rod serves as the origin for nearly the entire posterior portion of M. pectoralis major, although it does not serve as the entire origin as in T. semitaeniatus. Regardless of whether the posteriormost xiphisternal cartilage ends freely or is continuous with a bony rib, it appears to serve as the site of origin for a portion of M. pectoralis major. This appears to be the case even in those taxa that have extremely short cartilaginous protuberances projecting posteriorly from a second xiphisternal rib, for example G. silus and certain phrynosomatids (Etheridge, 1964). Suprascapulae (Character 42).-The suprascapulae are composed entirely of calcified cartilage and lie dorsal to the scapulae. In Croraphytus and some Gambelia, a deep notch is present in the anterior margin of the suprascapula giving it the ap- pearance of a hook. This notch is usually present in Croraphyrus and variably present in Gambelia (five of 23 wislizenii, one of seven copei, one of five G. silus). Most of the outgroup taxa lack a strongly developed notch in the suprascapula (present in one of one Corytophanes hernandezi and four of four Lrma scoparia). Therefore, the presence of a supra- scapular notch is treated as the derived state. Scapulae, Coracoids, and Epicoracoids (Charac- ters 43,44). -In crotaphytids, the posterior coracoid fenestrae are nearly always present (absent on one side only in one of five specimens of C. insularis, and on one side only in one of 23 G. \vislizenii). In C. rericularus, the posterior coracoid fenestrae were observed to be absent in three of nine individuals. Furthermore, they were either proportionally smaller or present unilaterally in the remaining large specimens, suggesting that the fenestrae are lost late in ontogeny in this species. Posterior coracoid fenestrae are absent in the great majority of iguanians and among the outgroup taxa are present in Uro- ntastyx. Liolaentus, Stenocercini, Tropidurini, iguanids exclusive of Dipsosaurus and Brachylophus. para-anoles, Enyalius, Pristidactylus. Leiosaurus. and Diplolaetnus (Savage, 1 958; Etheridge, 1 959; Moody, 1980; de Queiroz, 1987; Frost and Ether- idge, 1989). The weakly developed posterior Cora- coid fenestrae of the latter three taxa were considered by Frost and Etheridge (1989) to represent a separate character state. The presence of posterior coracoid fenestrae are considered to be the derived state and may represent a synapomorphy for Cro- taphytidae. The ontogenetic loss of the posterior coracoid fenestrae in C. reticulatus may represent an autapomorphy for the species. However, additional osteological material is required to evaluate this potentially distinct character state and it was not treated as such in the phylogenetic analysis. In Garnbelia, a calcified extension of the epicor- acoid cartilage forms the anterior border of the scapular fenestra. The anterior border of the scapular fenestra was either absent or incomplete in all of the Croraphytus specimens examined except three of 2 1 C. bicincrores, one of 12 C. collaris, one of five C, grismeri, one of five C. insularis, and three of 21 C. vestigiutn. However, in all of these specimens except two of the three C. vesrigiurn and the one C. collaris. the border of the fenestra was not completed by calcified cartilage, but rather by a thin sheet of bone or connective tissue. In adult C. rericularus, the calcified cartilage extends dorsally from the ventral border of the scapular fenestra approximately half way to the dorsal border of the fenestra, a condition that may represent an intermediate step between the condition observed in Gambelia and that observed in most other Croraphytus. Because the cartilage was present in 34 of 35 specimens of Gambelia examined, it seems unlikely that the variation observed was an artifact of preparation. Character polarity could not be evaluated in many of the outgroup taxa because they lack scapular fenestrae, including Cha- maeleonidae, Polychrotidae (variable in Polychrus), Corytophanidae, Liolaeminae, Hoplocercidae (except Enyalioides lariceps), Petrosaurus, Uta, and Urosaurus (Frost and Etheridge, 1989). In those outgroup taxa that have scapular fenestrae, most have the calcified cartilage borders, including phrynosomatids (except P. orbiculare), hoplocercids, oplurids, iguanids, tropidurids (Leiocephalw and Ura- noscodon), and Hydrosaurus arnboiensis (other aga- mines lack scapular fenestrae [Frost and Etheridge, 19891). Therefore, the absence ofa calcified cartilage
Page 1 and 2: OF CARNEGIE MUSEUM OF NATURAL HISTO
Page 3 and 4: BULLETIN OF CARNEGIE MUSEUM OF NATU
Page 5 and 6: ...................................
Page 7 and 8: 2 BULLETIN CARNEGIE MUSEUM OF NATUR
Page 15 and 16: BULLETIN CARNEGIE MUSEUM OF NATURAL
Page 21 and 22: 16 BULLETIN CARNEGIE MUSEUM OF NATU
Page 33: 28 BULLETIN CARNEGIE MUSEUM OF NATU
Page 39 and 40: BULLETIN CARNEGIE MUSE .UM OF NATUR
Page 45: BULLETIN CARNEGIE MUSEUM OF NATURAL
Page 48 and 49: this taxon is tentatively coded as
Page 50 and 51: McGUIRE-SYSTEMATICS OF CROTAPHYTID
Page 54 and 55: 1996 McGUIRE-SYSTEMATICS OF CROTAPH
Page 56 and 57: C. nebrius. at least three easily r
Page 62 and 63: 1996 McGUIRE- SYSTEMATICS OF CROTAP
Page 70 and 71: McGUIRE- SYSTEMATICS OF CROTAPHYTID
Page 78 and 79: es, and the absence of extravomerin
Page 82 and 83: McGUIRE- SYSTEMATICS OF CROTAPHYTID
Page 84 and 85:
1996 McGUIRE-SYSTEMATICS OF CROTAPH
Page 86 and 87:
McGUIRE- SYSTEM.4TICS OF CROTAPHYTI
Page 88 and 89:
McGUIRE-SYSTEMATICS OF CROTAPHYTID
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
spersed with numerous interstitial
Page 96 and 97:
of the Tucson Valley in the Santa C
Page 98 and 99:
C. vestigiurn by the absence in adu
Page 100 and 101:
McGUIRE- SYSTEMATICS OF CROTAPHYTID
Page 102 and 103:
Page 104 and 105:
McGUIRE- SYSTEMATICS OF CROTAPHYTID
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
McGUIRE-SY STEMATICS OF CROTAPHYTID
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
1996 McGUIRE- SYSTEMATICS OF CROTAP
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
yaaaa aaaay ????? yaaaa yaaaa ayayy
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
McGUIRE-SY STEMATICS OF CROTAPHYTID
Page 142 and 143:
Cbrr- Branch acler Steps 31 38 33 2
Page 144 and 145:
Page 146:
show all

Download Full Document - Mountain Boomer Music!

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?