Table 1. Selected cranial measurements (in mm) of the YPM-PU 22400 perinatal specimens of Maiasaura peeblesorum.

Measurements are taken on the most complete maxilla (Figs. 2A–2D), jugal (Fig. 3D), quadrate (Fig. 3C), and dentary (Figs. 4A–4C). All other maxillae, jugal, quadrate, and dentaries are of a size similar to that of the measured bones.

Element	Measurement
Maxilla, total length	60
Maxilla, height from ventral margin to apex of dorsal process (incomplete)	20
Maxilla, length of ectopterygoid shelf	25
Maxilla, maximum width across ectopyerygoid shelf	14
Jugal, length from incomplete rostral process to incomplete quadratojugal flange	42
Jugal, height from ventral margin to incomplete apex of postorbital process	23
Quadrate, height from lateral condyle to articular head	61
Dentary, total length	58
Dentary, dental battery length	49
Dentary, maximum dental battery depth	22
Dentary, maximum depth of mandibular ramus	19
Dentary, width at mid-length of the dental battery	12