Dicephalus is common in reptiles and particularly in British grass snakes, who lay their eggs inside compost heaps where decomposing matter produces heat.

• 双头畸胎在爬行动物中很常见，尤其是英国草蛇，这种蛇把卵产在堆肥堆里，肥料里面正在腐烂的物质产生热量。