Though not phylogenetic in methodology, the Popham examines their distribution patterns and concludes that their center of origin was Gondwana, in the area that is now northeast Brazil and northwest Africa.

• 虽然方法上没有系统性，Popham调查它们的分布型得出它们的起源中心是冈瓦纳，目前分布于巴西东北和非洲西北。