Synchrotron imagery of phosphatized eggs in Waptia cf. W. fieldensis from the middle Cambrian (Miaolingian; Wuliuan) Spence Shale of Utah

Exceptionally preserved fossil eggs and embryos provide critical information regarding paleoembryogenesis, reproductive strategies, and the early ontogeny of early arthropods, but the rarity of preservation of both eggs and egg-bearing organisms in situ limits their use in detailed evo-devo studies. Burgess Shale-type deposits preserve rare instances of egg-bearing arthropods as carbonaceous compressions, however, the eggs are usually poorly preserved with no compelling evidence of embryos. We describe the first record of a brooding specimen of Waptia cf. fieldensis from the Spence Shale, a Cambrian (Wuliuan stage) Burgess Shale-type deposit in northeastern Utah and southeastern Idaho. This is the first record of an egg-bearing arthropod from the Spence Shale and it exhibits two distinct modes of preservation among eggs within the single clutch: carbonization and phosphatization. Unlike the egg-bearing Burgess Shale specimens, many eggs of this Utah specimen are also preserved three-dim...保存极为完好的化石卵与胚胎，可为早期节肢动物的古胚胎发育、繁殖策略及早期个体发育提供关键信息，但原位保存的卵及携卵生物均极为罕见，这极大限制了其在精细进化发育生物学（evo-devo）研究中的应用。布尔吉斯页岩型（Burgess Shale-type）矿床虽偶有保存为碳质压型化石的携卵节肢动物实例，但这类标本的卵通常保存状态欠佳，尚无确凿证据证实胚胎的存在。本次研究报道了产自斯潘斯页岩（Spence Shale）的首例疑似菲尔德瓦普塔虾（Waptia cf. fieldensis）孵卵标本；斯潘斯页岩是一处分布于犹他州东北部与爱达荷州东南部的寒武纪伍里统阶布尔吉斯页岩型矿床。这是斯潘斯页岩地区首次发现的携卵节肢动物化石记录，其单窝卵展现出两种截然不同的保存模式：碳化与磷酸盐化。与已发表的布尔吉斯页岩携卵标本不同，该犹他州标本的多数卵仍以三维形态保存...