Varricchio David J, Moore Jason R, Erickson Gregory M, Norell Mark A, Jackson Frankie D, Borkowski John J
Department of Earth Sciences, Montana State University, Bozeman, MT 59717, USA.
Science. 2008 Dec 19;322(5909):1826-8. doi: 10.1126/science.1163245.
The repeated discovery of adult dinosaurs in close association with egg clutches leads to speculation over the type and extent of care exhibited by these extinct animals for their eggs and young. To assess parental care in Cretaceous troodontid and oviraptorid dinosaurs, we examined clutch volume and the bone histology of brooding adults. In comparison to four archosaur care regressions, the relatively large clutch volumes of Troodon, Oviraptor, and Citipati scale most closely with a bird-paternal care model. Clutch-associated adults lack the maternal and reproductively associated histologic features common to extant archosaurs. Large clutch volumes and a suite of reproductive features shared only with birds favor paternal care, possibly within a polygamous mating system. Paternal care in both troodontids and oviraptorids indicates that this care system evolved before the emergence of birds and represents birds' ancestral condition. In extant birds and over most adult sizes, paternal and biparental care correspond to the largest and smallest relative clutch volumes, respectively.
成年恐龙与一窝窝恐龙蛋紧密关联的反复发现，引发了人们对这些已灭绝动物对其蛋和幼崽的照料类型及程度的猜测。为了评估白垩纪伤齿龙科和窃蛋龙科恐龙的亲代照料行为，我们研究了窝卵数以及孵卵成年恐龙的骨骼组织学。与四种主龙类的照料行为回归分析相比，伤齿龙、窃蛋龙和慈母龙相对较大的窝卵数与鸟类父系照料模式最为契合。与窝卵相关的成年恐龙缺乏现存主龙类常见的母系和生殖相关的组织学特征。仅与鸟类共有的大窝卵数和一系列生殖特征支持父系照料行为，可能存在于一夫多妻制的交配系统中。伤齿龙科和窃蛋龙科的父系照料行为表明，这种照料系统在鸟类出现之前就已演化出来，代表了鸟类的祖先状态。在现存鸟类中，在大多数成年体型下，父系照料和双亲照料分别对应最大和最小的相对窝卵数。
