Kear Benjamin P
School of Earth and Environmental Science, University of Adelaide, Adelaide 5006, Australia.
Biol Lett. 2006 Mar 22;2(1):113-5. doi: 10.1098/rsbl.2005.0374.
Modern sea turtles utilize a variety of feeding strategies ranging from herbivory to omnivory. In contrast, the diets of fossil sea turtles are poorly known. This study reports the first direct evidence: inoceramid bivalve shell pieces (encased in phosphatic material) preserved within the body cavities of several small protostegid turtles (cf. Notochelone) from the Lower Cretaceous of Australia. The shell fragments are densely packed and approximately 5-20 mm across. Identical shell accumulations have been found within coprolite masses from the same deposits; these are of a correct size to have originated from Notochelone, and indicate that benthic molluscs were regular food items. The thin, flexible inoceramid shells (composed of organic material integrated into a prismatic calcite framework) appear to have been bitten into segments and ingested, presumably in conjunction with visceral/mantle tissues and encrusting organisms. Although protostegids have been elsewhere interpreted as potential molluscivores, their primitive limb morphology is thought to have limited them to surface feeding. However, the evidence here that at least some forms were able to utilize benthic invertebrate prey indicates that, like modern sea turtles, protostegids probably exhibited a much broader range of feeding habits.
现代海龟采用多种摄食策略，从食草到杂食不等。相比之下，化石海龟的饮食情况却鲜为人知。本研究报告了首个直接证据：在澳大利亚下白垩统的几只小型原盖龟科海龟（cf. 诺托凯伦龟）的体腔内保存有包在磷酸盐物质中的三角蛤双壳类贝壳碎片。这些贝壳碎片密集堆积，直径约5 - 20毫米。在同一沉积层的粪化石团块中也发现了相同的贝壳堆积物；它们的大小与源自诺托凯伦龟的贝壳相符，表明底栖软体动物是其常见食物。薄而柔韧的三角蛤贝壳（由融入棱柱形方解石框架的有机物质组成）似乎被咬成碎片并被吞食，推测是与内脏/外套膜组织和附着生物一起被吃掉的。尽管原盖龟科在其他地方被解释为潜在的食软体动物者，但其原始的肢体形态被认为限制了它们只能进行表层摄食。然而，这里有证据表明至少某些种类能够捕食底栖无脊椎动物猎物，这表明原盖龟科可能像现代海龟一样，表现出更为广泛的摄食习性。
