Extended Data Fig. 7: Internal anatomy of the postbranchial wall in the osteostracan Norselaspis glacialis reveals crown gnathostome-like traits of the head-trunk interface.
From: Novel assembly of a head–trunk interface in the sister group of jawed vertebrates
(a–d) The postbranchial wall of a jawless stem gnathostome Norselaspis glacialis (MNHN-F-SVD3221) reconstructed with solid (first row) and semi-transparent (second row) skeletal correlates and without them (third row) in dorsal (a), ventral (b), anterior (c), and posterior (d) views. The upper ≠head shield is removed. (e) Digital dissection of the postbranchial wall of Norselaspis glacialis (MNHN-F-SVD3221) in dorsal view, with the roof of the intramural cavity removed (e1), with further removal of the common cardinal veins and sinus venosus (e2), with horizontal section at a lower level, revealing the heart (e3), and with restoration of the venous structures (e4), progressing from left to right. (f) Sagittal section of the postbranchial wall of Norselaspis glacialis (MNHN-F-SVD3221) in medial view, mirrored to show the better-preserved left half, with bare bones with a magnified panel (f1) and with the pericardial and cardiac structures restored (f2). (g) Anatomy of the postbranchial wall of Norselaspis glacialis (MNHN-F-SVD3221) in left lateral view, with semitransparent skeleton (g1) and with internal soft tissues only in which the venous structures are rendered semitransparent (g2). (h–l) The heart and venous drainage of Norselaspis glacialis (MNHN-F-SVD3221) in dorsal (h), ventral (i), anterior (j), posterior (k), and left lateral view (l). Panels a–f are to scale; panels h–l are also to scale. For the key to Roman numerals, see Fig. 1.
