Fig. 1

Generalized figure of the vertebral anatomy of Constrictores, based on a trunk vertebra of Boa constrictor (specimen SMF-PH 40). Anatomical structures labelled in black and measurements labelled in red. CL, centrum length, measured ventrally and including the condyle; cn., condyle; co., cotyle; CoW, cotyle width; dp., diapophysis; h.k., haemal keel; hPO-PO, half-width of distance between the outer edges of the postzygapophyses; inz. ridge, interzygapophyseal ridge; NAH, neural arch height; NAW, neural arch width, measured at the maximum interzygapophyseal constriction; nsp., neural spine; NSPL, neural spine length; pco.f., paracotylar foramen; poz., postzygapophysis; PO-PO, distance between the outer edges of the postzygapophyses; pp., parapophysis; prz., prezygapophysis; prz. pr., prezygapophyseal accessory process; sc.f., subcentral foramen; sc.r., subcentral ridge; zgs., zygosphene; zgt., zygantrum; ZW, zygosphene width