Therapsids were a dominant component of middle–late Permian terrestrial ecosystems worldwide, eventually giving rise to mammals during the early Mesozoic. However, little is currently known about the time and place of origin of Therapsida. Here we describe a definitive therapsid from the lower–?middle Permian palaeotropics, a partial skeleton of a gorgonopsian from the island of Mallorca, western Mediterranean. This specimen represents, to our knowledge, the oldest gorgonopsian record worldwide, and possibly the oldest known therapsid. Using emerging relaxed clock models, we provide a quantitative timeline for the origin and early diversification of therapsids, indicating a long ghost lineage leading to the evolutionary radiation of all major therapsid clades within less than 10 Myr, in the aftermath of Olson’s Extinction. Our findings place this unambiguous early therapsid in an ancient summer wet biome of equatorial Pangaea, thus suggesting that the group originated in tropical rather than temperate regions.

Therapsids 是全球二叠纪中晚期陆地生态系统的主要组成部分，最终在中生代早期产生了哺乳动物。然而，目前对 Therapsida 的起源时间和地点知之甚少。在这里，我们描述了来自中下二叠纪古热带的确定的 therapsid，这是来自西地中海马略卡岛的 gorgonopsian 的部分骨骼。据我们所知，这个标本代表了世界上最古老的 gorgonopsian 记录，也可能是已知最古老的 therapsid。使用新兴的松弛时钟模型，我们为 therapsids 的起源和早期多样化提供了定量时间表，表明在 Olson 灭绝之后，一个漫长的幽灵谱系导致所有主要 therapsid 分支在不到 10 Myr 的进化辐射。我们的研究结果将这种明确的早期 therapsid 置于赤道 Pangaea 的古老夏季潮湿生物群落中，从而表明该类群起源于热带地区而不是温带地区。