. Bonner zoologische Monographien. Zoology. 89 Hoffstetter & Gase (1969) devised a simple convention for representing rib articulating patterns and presacral vertebrae in a serial fashion. The most common presacral formu- la in "iguanids" is 4 + 4 + 6(4 + 2) +10=24. The first number represents the number of cervical vertebrae without ribs, the second integer the number of cervical vertebrae bearing ribs. It can be deduced from the general formula of rib articulation that the fifth cervical vertebra is the first to bear any ribs at all. The third number (6) shows the number of tho
. Bonner zoologische Monographien. Zoology. 89 Hoffstetter & Gase (1969) devised a simple convention for representing rib articulating patterns and presacral vertebrae in a serial fashion. The most common presacral formu- la in "iguanids" is 4 + 4 + 6(4 + 2) +10=24. The first number represents the number of cervical vertebrae without ribs, the second integer the number of cervical vertebrae bearing ribs. It can be deduced from the general formula of rib articulation that the fifth cervical vertebra is the first to bear any ribs at all. The third number (6) shows the number of thoracic vertebrae, followed in parentheses by the number of vertebrae that have costal connections to the sternum (4) and those vertebrae that have rib ar- ticulations with the xiphisternum (2). In other words, six ribs articulate with the ster- num, four of which have a direct connection to the sternum (sternal ribs) and two con- nect to the sternum via the xiphisternum (xiphisternal ribs). The sixth number (10) represents the number of lumbar vertebrae. There is no distinction made in this formula between rib-bearing lumbar vertebrae and non rib-bearing vertebrae. The last number (24) indicates the total number of presacral vertebrae (See character no. 41). C h a r a c t e r 45: rib articulating patterns (Fig. 36A & 36B). As mentioned by Hoff- stetter & Gase (1969), the 6(4 + 2) condition is the most widespread condition in "igua- nids". In this condition, the ribs on vertebrae 9—12 attach to the sternum, whereas the ribs of vertebrae 13 + 14 attach to the xiphisternum. Three alternative conditions occur. C)7(4+3) pattern D)5(3+2) pattern Fig. 36: A Ventral view of the pectoral girdle of Laemanctus serratus showing various skeletal ele- ments. B: Ventral view of pectoral girdles of basiliscines showing variation in rib articulation pat- terns: A) 6(4 + 2) B) 6(3 + 3) C)7(4 + 3) D) 5(3+2).. Please note that these images are extracted from scanned page images
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