Department of Earth Sciences, University of Oregon, Eugene, Oregon, United States of America.
PLoS One. 2022 Jun 16;17(6):e0269638. doi: 10.1371/journal.pone.0269638. eCollection 2022.
Recently reported specimens of the enigmatic Ediacaran fossil Dickinsonia from Russia show damage and repair that provides evidence of how they grew, and of their biological affinities. Marginal and terminal areas of wilting deformation are necrotic zones separating regenerated growth, sometimes on two divergent axes, rather than a single axis. Necrotic zones of damage to Dickinsonia are not a thick scar or callus, like a wound or amputation. Nor are they smooth transitions to a regenerated tail or arm. The wilted necrotic zone is most like damage by freezing, salt, or sunburn of leaves and lichens, compatible with evidence of terrestrial habitat from associated frigid and gypsic paleosols. Dickinsonia did not regrow by postembryonic addition of modules from a subterminal or patterned growth zone as in earthworms, myriapods, trilobites, crustaceans, and lizards. Rather Dickinsonia postembryonic regrowth from sublethal damage was from microscopic apical and lateral meristems, as in plants and lichens. Considered as fungal, Dickinsonia, and perhaps others of Class Vendobionta, were more likely Glomeromycota or Mucoromycotina, rather than Ascomycota or Basidiomycota.
最近报道的俄罗斯神秘的埃迪卡拉纪化石迪基多尼亚的标本显示出损伤和修复的迹象,这为它们的生长方式和生物亲缘关系提供了证据。萎蔫变形的边缘和末端区域是坏死区,将再生生长分隔开,有时是在两个发散的轴上,而不是单一的轴上。对迪基多尼亚的损伤坏死区不是像伤口或截肢那样的厚疤痕或愈伤组织。它们也不是向再生的尾巴或手臂的平滑过渡。萎蔫的坏死区最类似于叶子和地衣的冻害、盐害或晒伤造成的损伤,与相关的寒冷和石膏古土壤中陆地栖息地的证据相吻合。迪基多尼亚没有像蚯蚓、多足类动物、三叶虫、甲壳类动物和蜥蜴那样通过胚胎后从亚末端或图案化生长区添加模块来再生。相反,迪基多尼亚在亚致死性损伤后的胚胎后再生来自微观的顶端和侧生分生组织,就像植物和地衣一样。被认为是真菌的迪基多尼亚,也许还有其他 Vendobionta 类,更可能是 Glomeromycota 或 Mucoromycotina,而不是 Ascomycota 或 Basidiomycota。