Figure 3: Scientific Reports

Figure 3

From: Orthrozanclus elongata n. sp. and the significance of sclerite-covered taxa for early trochozoan evolution

Figure 3

Scleritome arrangement in Orthrozanclus elongata n. sp. (a, NIGPAS164892), Halkieria evangelista (b, Sedgwick Museum of Earth Sciences  X24914.2) and Wiwaxia corrugata (c, Royal Ontario Museum 61510). The Orthrozanclus (d) and Halkieria (e) scleritomes are arranged in three concentric zones: a medial zone of oblique transverse rows (vermillion); a dorsolateral ‘inner peripheral’ zone (purple), containing long spines in Orthrozanclus and cultrate sclerites in Halkieria; and a ventrolateral ‘outer peripheral’ zone, containing cultrate (Orthrozanclus) or siculate (Halkieria) sclerites. Dailyatia bacata (f) is reconstructed as having a medial region containing A and B sclerites and a single peripheral zone of C sclerites. The approximately 4:1 ratio of C1:A sclerites and 4:2 ratio of C2:B sclerites35 is taken to indicate that C sclerites occur at twice the frequency of elements in the medial zone. The Wiwaxia scleritome (g) comprises eight transverse rows (shaded) intersected by two rows of intermittently spaced spines.