Booidea

Diagnosis. There are not many vertebral characters defining the diverse group of booid snakes; the most commonly cited characters include the presence of lateral foramina and higher neural arches than those found in Anilioidea (Holman, 2000; modified from Rage, 1984; supported by Ikeda, 2007). Furthermore, in pythonids, the shape of the hemal keel is defined by grooves or depressions beginning at the cotylar rim, but projecting below the centrum only in the posterior part of each vertebra (Scanlon and Mackness, 2001; Szyndlar and Rage, 2003).

Remarks. Skeletal characters used to describe Booidea are primarily based on cranial elements (see Georgalis and Smith, 2020). In comparison to colubroids, booid vertebrae are generally less slender and elongate, and tend to have shorter and broader neural spines in at least North American species (Holman, 2000; Smith, 2013). Booidea can often be separated from Pythonoidea based on greater intracolumnar heterogeneity in the former (Szyndlar and Rage, 2003), and thicker zygosphenes in the latter when compared to similarly sized booids, although there is some amount of variability in this character (Georgalis and Smith, 2020).