Postnatal skeletal ontogeny in five Xantusiids (Squamata: Scleroglossa)



The construction of a comparative database of squamate postnatal skeletal development is continued with the detailed description of the mineralization of the skeleton from birth to near maximum size in Lepidophyma gaigeae and four Xantusia taxa. Observed patterns in the sequence of appearance of epiphyseal secondary centers, ossification centers, apophyseal ossifications, and calcifications, the distribution of sesamoids, and the timing of fusions are compared and contrasted with other squamates. Xantusiids share a similar sequence of braincase fusions, but differ in the sequence of appearance of ossification centers and epiphyseal secondary centers. Relative to other squamates they exhibit an immature neonatal state of ossification, a delayed appearance of ossification centers and epiphyseal secondary centers, and an accelerated appearance of apophyses. All five xantusiid taxa possess two sesamoids previously unreported in squamates. These observations add to the growing body of evidence that morphogenesis and osteogenesis are largely independent developmental phenomena. J. Morphol. 254:1–38, 2002. © 2002 Wiley–Liss, Inc.