伤齿龙(Troodontids)筑巢产卵的行为

应用薄壳理论研究中国和北美西部出土的晚侏罗世至晚白垩世伤齿龙蛋以平卧和竖立两种方式埋在沙土中受压破损的抵抗能力 ,分析伤齿龙蛋在蛋窝中特有的排列方式与其蛋壳的抗失稳能力之间的关系。结果表明 ,由于伤齿龙蛋壳很薄 ,其抗失稳能力很差 ,如果这种蛋以横卧方式埋在沙土中就可能在很小载荷下因失稳屈曲而破裂 ;但是 ,如果把蛋竖立起来埋在沙土中 ,则蛋的抗破碎能力比把它们平放埋在沙土中要高出 4～ 5倍。从而认为 ,伤齿龙在筑巢产卵时把一个个蛋竖立起来埋在沙土中是为解决其低强度蛋壳在保护胚胎 ,避免外力损伤和在卵的孵化后期幼雏能够破壳而出这两方面的矛盾而采取的一种保护性措施 ,说明这些体征很像鸟类的兽脚类恐龙 ,其智商可能比人们想象的要高。在此基础上 ,探讨和复原了伤齿龙筑巢产卵的行为。

THE NESTING BEHAVIOR OF TROODONTID DINOSAURS

Abstract>Summary Thetroodontideggshavebeenpreservedstandinguponthenest,pointedendsdownwards,so thattheylookedasiftheyhadbeenstuckinthegroundwhentheywerelaid(seeFig .5ofHorner, 1984;Fig.3dofHirschandQuinn ,1990 ;PlateIofZhaoandLi,1993;Fig.1ofZhao ,2 0 0 0 ) .Why didthetroodontidsputtheireggsverticallyintotheearthatnesting?Doesthenestingbehaviorhave anypaleobiologicalsignificance? ThetroodontideggswereinitiallydescribedasprismatoolithideggshellsbyHirschandQuinn ( 1990 )fromWesternMontana,USAandformallynamedbyZhaoandLi( 1993) .Theseeggswere initiallyassignedtohypsilophodontidOrodromeusmakelai,basedonembryonicremainswithineggs fromWesternMontana (HornerandWeshampel,1988) .However,ithasbeenannounced (Horner andWeshampel,1996 )thattheinitialidentificationoftheseembryoswaserroneous.Theywerere i dentifiedasthesmalltheropodTroodoncf.T .formosus,ratherthanOrodromeusmakelai.