Fig 1.
Specimen NMQR 3636 in left lateral view.
a, photograph of the specimen; b, 3D digital reconstruction of the segmented bones; c, live reconstruction by artist Sophie Vrard. Colour code for b: vertebral elements in shades of green, ribs in blue, forelimb elements in red, femur in yellow, pelvic girdle elements in grey, skull in light red, mandible in light orange.
Fig 2.
Comparison of cranial features of perinate Lystrosaurus specimens.
From left to right, NMQR 3636, BP/1/4011, and BP/1/9332. a, photographs of the skulls in lateral view; b, 3D digital transparent skull showing the tusk (in black) and mesethmoid (in grey), if preserved. The dotted lines marked “c” and “e” indicate the planes of view displayed in the sections of panel c and e; c, coronal CT section through the tusk sockets; d, 3D model of lower jaws in anterior view to display the symphysis. The black arrow points to the symphyseal gap in NMQR 3636; e, CT cross sections through the mandibular symphysis in two positions in NMQR 3636 (left and middle) and BP/1/9332 (right) showing the state of ossification of the rostral mandibular bones. Arrows point to incompletely co-ossified sutures. Abbreviations: Dt., dentary; Sp., splenial.
Fig 3.
Comparison of two perinate Lystrosaurus skeletons.
a, 3D digital reconstruction of NMQR 3636 in left lateral view showing the complete skeleton (left), the skull, lower jaw and vertebrae only (middle), and the pelvis and femur only (right); b, 3D digital reconstruction of NMQR 3636 in right lateral view with (left) and without the ribs (right); c, comparison between the right humerus of NMQR 3636 and the left humerus (mirrored) of BP/1/9332; d, reconstructed lateral view of the preserved skeletal elements belonging to NMQR 3636; e, photograph of BP/1/9332 in dorsal view. Colour code for a and b: vertebral elements in shades of green, ribs in blue, forelimb elements in red, femur in yellow, pelvic girdle elements in grey, skull in light red, mandible in light orange. Abbreviations: Ent.f., entepicondylar foramen; Fem., femur; Hum.l., left humerus; Hum.r., right humerus; Il.l., left ilium; Il.r., right ilium; Is.l., left ischium; Is.r., right ischium; Man., manus; Rad., radius; Ul., ulna.
Fig 4.
Plot of egg mass against body mass in amniotes (logged).
Colour code: red, Lystrosaurus; Purple, Kayentatherium; Yellow, birds; Green, non-avian reptiles. Data after [45].