阿根廷研究团队在一具236百万年前的犬齿龙（Chiniquodon theotonicus）化石中发现了迄今最早的哺乳动物胎生繁殖证据1。通过分析化石骨骼中的新生线和推断新生儿体重，科研人员确定该物种新生儿体重约为1.7千克，占成体体重（约12千克）的14%1，这一比例与现代胎盘哺乳动物相近1。
CONICET古生物学家莱安德罗·盖塔诺博士领导的研究团队指出："我们首次证明了胎生在至少一种哺乳动物祖先——生活在大约236百万年前的犬齿龙中是存在的"1。这一发现将哺乳动物谱系中胎生繁殖的起源时间大幅前移，比之前的认识早了90至95百万年1。
Scientists have discovered the earliest known evidence of live birth in a mammalian ancestor, pushing back the origins of this reproductive strategy by approximately 90 to 95 million years. The findings come from analysis of a 236-million-year-old fossil of Chiniquodon theotonicus, a mammal-like creature discovered in northwestern Argentina.1
The research team, led by Dr. Leandro Gaetano from Argentina's National Scientific and Technical Research Council (CONICET), examined skeletal markers in the fossil to estimate the newborn's weight at approximately 1.7 kilograms, compared to an estimated adult body mass of around 12 kilograms.1 This ratio of newborn to adult weight—approximately 14 percent—closely mirrors that of modern placental mammals, suggesting a reproductive strategy fundamentally different from that of reptiles or birds.1 As Dr. Gaetano and colleagues stated in their research: "We show for the first time that live birth was present in at least one mammalian ancestor, Chiniquodon theotonicus, which lived approximately 236 million years ago."1
The study, published in Frontiers in Mammal Science in 2026, demonstrates that viviparous reproduction—the bearing of live young—originated much earlier in mammalian evolutionary history than previously documented.1
评论
还没有评论，欢迎留下第一条。