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Fig. 4 | BMC Evolutionary Biology

Fig. 4

From: Further study of Late Devonian seed plant Cosmosperma polyloba: its reconstruction and evolutionary significance

Fig. 4

Bifurcate fronds of Cosmosperma polyloba. a Combined figure of part and counterpart of one specimen, exhibiting frond with primary rachis ending in a dichotomy (arrow 1, enlarged in Fig. 4 b), two secondary rachises, alternately (pinnately) arranged tertiary rachises and an attached ultimate pinna (quaternary rachis and pinnules; arrow 2, enlarged in Fig. 4 c). A cupulate ovule (arrow 3, enlarged in Fig. 6 d) is associated with the frond. PKUB13509a, PKUB13509b (above the dashed line). Scale bar = 20 mm. b Enlargement of Fig. 4(a, arrow 1), showing the dichotomy of primary rachis. Note parallel vertical striations and conical prickles (arrows) along the primary rachis and basal part of secondary rachises. Scale bar = 5 mm. c Enlargement of Fig. 4 (a, arrow 2), showing one ultimate pinna with highly dissected, alternate and planate pinnules. Arrows indicating conical prickles along quaternary rachis. Scale bar = 5 mm. d Longest primary rachis with base but without distal portion preserved. PKUB13508. Scale bar = 20 mm

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