Botha Jennifer
Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.
GENUS: DSTI-NRF Centre of Excellence in Palaeosciences, University of the Witwatersrand, Johannesburg, South Africa.
J Anat. 2025 Jun;246(6):987-1000. doi: 10.1111/joa.14201. Epub 2024 Dec 20.
During the Late Permian, saber-toothed gorgonopsian therapsids were the dominant terrestrial predators, playing crucial roles as apex predators alongside therocephalian therapsids within Permian terrestrial ecosystems. The entire gorgonopsian clade went extinct during the Permo-Triassic mass extinction, leaving other therapsids to continue into the Triassic. Gorgonopsians have not been well studied, particularly in terms of their growth patterns, with only a few genera having undergone osteohistological analysis. In this study, I present a thorough osteohistological examination of the most extensive collection of gorgonopsian specimens to date, spanning a diverse range of limb bones sourced from various species. The osteohistological analysis of gorgonopsian specimens reveals a trend of rapid growth characterized by a highly vascularized woven-parallel complex. The abundance of growth marks and variable zone widths suggests a growth trajectory that could indicate longer lifespans and slower growth rates when compared to Early Triassic therapsids. The high vascularity, coupled with the observed growth patterns, implies that gorgonopsians experienced rapid growth during favorable conditions. However, the multiple growth marks indicate that they likely had the capacity for longer lifespans and more gradual maturation than their Early Triassic counterparts. Additionally, their ability to reach later ontogenetic stages supports the hypothesis that favorable environmental conditions facilitated larger body sizes. In contrast, Early Triassic therapsids primarily consisted of juveniles or individuals who reached reproductive maturity within a year, likely indicative of harsher conditions that contributed to higher mortality rates at younger ages. The onset of decreased growth rates, usually indicative of reproductive maturity, occurred later in gorgonopsians compared to Early Triassic therapsids and may have contributed to their decline, as the heightened juvenile mortality rates during the PTME would have limited the gorgonopsians' ability to reproduce effectively.
在二叠纪晚期，长着 saber 齿的蛇发女怪龙兽孔目兽类是主要的陆地食肉动物，在二叠纪陆地生态系统中作为顶级食肉动物与兽头亚目兽孔目动物发挥着关键作用。整个蛇发女怪龙兽孔目类群在二叠纪 - 三叠纪大灭绝期间灭绝，留下其他兽孔目动物延续到三叠纪。蛇发女怪龙兽类尚未得到充分研究，特别是在其生长模式方面，只有少数属进行过骨组织学分析。在本研究中，我对迄今为止最广泛的蛇发女怪龙兽类标本进行了全面的骨组织学检查，这些标本涵盖了来自各种物种的不同肢体骨骼。蛇发女怪龙兽类标本的骨组织学分析揭示了一种以高度血管化的编织 - 平行复合体为特征的快速生长趋势。生长标记的丰富性和可变的区域宽度表明其生长轨迹，与早三叠世兽孔目动物相比，这可能意味着更长的寿命和更慢的生长速度。高血管化以及观察到的生长模式表明，蛇发女怪龙兽类在有利条件下经历了快速生长。然而，多个生长标记表明它们可能比早三叠世的同类具有更长的寿命和更缓慢的成熟过程。此外，它们达到后期个体发育阶段的能力支持了这样的假设，即有利的环境条件促进了更大的体型。相比之下，早三叠世兽孔目动物主要由幼体或在一年内达到生殖成熟的个体组成，这可能表明环境更恶劣，导致幼年死亡率更高。生长速率下降的开始，通常表明生殖成熟，在蛇发女怪龙兽类中比早三叠世兽孔目动物出现得更晚，这可能导致了它们的衰落，因为二叠纪 - 三叠纪大灭绝期间幼年死亡率的增加会限制蛇发女怪龙兽类有效繁殖的能力。
