Rethinking the egg
Rethinking the egg
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重新思考鸡蛋
DOI：
10.1093/nsr/nwad288
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发表时间：
2023
影响因子：
20.6
通讯作者：
Benton M
中科院分区：
文献类型：
--
作者：
Benton M
我们对早期恐龙蛋的印象必须改变。早期的恐龙蛋是软壳的，就像现代蜥蜴或蛇的蛋一样[1]，但所有的证据都表明，早期的恐龙至少会产皮革壳的蛋，更像是龟蛋，如Chelydra serpentina和Pseudemys nelsoni。这很重要，因为保护蛋是恐龙成功的关键，也是现代爬行动物和鸟类成功的关键。汉塔尔[2]详细描述了一个早侏罗纪蜥脚类恐龙的巢穴，蛋是皮革状的，不是软壳或硬壳。一个关键的进化转变是以羊膜卵为标志的，它使第一批爬行动物能够在陆地上安全地产卵，而没有干燥的风险，这标志着所有羊膜动物（=爬行动物+鸟类+哺乳动物）的成功。直到最近，第一个羊膜卵被认为是硬壳的，因为这是我们在现代鸟类，鳄鱼，海龟和单孔目哺乳动物中看到的。坚硬的蛋壳被矿化，包含碳酸钙的结晶单元。然而，皮革蛋是一些海龟和哺乳动物的典型特征[3，4]。例如，单孔目动物（针鼹鼠，鸭嘴兽）的蛋是矿化的，并且是白色的，就像鸡蛋一样，但实际上蛋壳是皮革状的，只有一层非常薄的矿化碳酸钙[3]。在海龟、海龟和一些陆龟（如
Our image of early dinosaur eggs must change. Earlydinosaur eggsareportrayed as soft-shelled, like those of modern lizards or snakes [1], and yet all the evidence is that early dinosaurs at least laid leathery-shelledeggs, morelikesometurtle eggs such as Chelydra serpentina and Pseudemys nelsoni. This matters because the protective egg is key to the success of dinosaurs, as well as modern reptiles andbirds. Hanetal.[2] presentadetailed account of the nest of an Early Jurassic sauropodomorph and the eggs are leathery, not soft-shelled or hard-shelled. A key evolutionary transition is marked by the amniotic egg, which enabled the first reptiles to lay their eggs safely on land without risk of their drying out, and this marks the success of all Amniota (= reptiles+ birds+ mammals). Until recently, the first amniotic egg was assumed to have been hardshelled because that is what we see in modern birds, crocodilians, turtles and monotreme mammals. The hard eggshell is mineralized, comprising crystalline units of calcium carbonate. However, a leathery egg is typical of some turtles and mammals [3, 4]. For example, the egg of monotremes (echidnas, platypus) is mineralized and white, like a hen’s egg, but in fact the eggshell is leathery with only a very thin layer of mineralized calcium carbonate [3]. Among turtles, sea turtles and some tortoises (eg