A Survey of State of Ossification in Neonatal Squamates

The state of ossification of the skeleton at hatching or birth and shortly thereafter is described and compared for 21 squamate species. The presence in the neonate of metapodial ossification centers and epiphyseal secondary centers varies among species, whereas the appearance of apophyseal ossifications and endochondral calcifications and the ossification of sesamoid precursors are predominantly postnatal phenomena. The data suggest a possible causal relationship between viviparity and skeletally immature neonates, whereas state of ossification at hatching or birth is probably attributable to phylogeny overall. Of the clades represented in this investigation, phrynosomatids, teiioids, and amphisbaenians exhibit the most skeletally mature neonates, whereas the reverse is true of gekkotans, xantusiids, and anguids.