Still, their fossilization required a suite of factors: a slow rate of decay of soft tissues, little scavenging by other animals, a lack of swift currents and waves to jumble and carry away small bones, and fairly rapid burial.

• 但是它们的石化需要一系列因素：软组织的腐烂速度缓慢，很少被其它动物残食，缺少混杂、冲走小骨头的快速水流和波浪，以及相当快地被掩埋。